Pub Date : 2025-02-12DOI: 10.1051/0004-6361/202452811
N. Jannsen, A. Tkachenko, P. Royer, J. De Ridder, D. Seynaeve, C. Aerts, S. Aigrain, E. Plachy, A. Bodi, M. Uzundag, D. M. Bowman, D. J. Fritzewski, L. W. IJspeert, G. Li, M. G. Pedersen, M. Vanrespaille, T. Van Reeth
Context. With the PLAnetary Transits and Oscillation of stars (PLATO) space mission set for launch in December 2026 by the European Space Agency (ESA), a new photometric legacy and a future of new scientific discoveries await the community. By exploring scientific topics outside of the core science program, the PLATO complementary science program (PLATO-CS) provides a unique opportunity to maximise the scientific yield of the mission.Aims. In this work, we investigate PLATO’s potential for observing pulsating stars across the Hertzsprung–Russell diagram (HRD). This search is distinct from the core science program. Here, we present a PLATO mock asteroseismic catalogue (MOCKA) of intermediate to massive stars as a benchmark to highlight the asteroseismic yield of PLATO-CS in a quantitative way. MOCKA includes simulations of β Cephei, slowly pulsating B (SPB), δ Scuti, γ Doradus, RR Lyrae, Cepheid, hot sub-dwarf, and white dwarf stars. In particular, main sequence gravity (g) mode pulsators are of interest, as some of these stars form an important foundation for the scientific calibration of PLATO. Their pulsation modes primarily probe the radiative region near the convective core boundary, making them unique stellar laboratories for studying the deep internal structure of stars.Methods. MOCKA is based on a magnitude-limited (G ≲ 17) Gaia catalogue. It is a product of realistic end-to-end PlatoSim simulations of stars for the first PLATO pointing field in the southern hemisphere, which will be observed for a minimum duration of two years. Comprising a state-of-the-art hare-and-hound detection exercise, the simulations of this project explore the impact of spacecraft systematics and stellar contamination on the on-board PLATO light curves.Results. We demonstrate, for the first time, PLATO’s ability to detect and recover the oscillation modes for main sequence g-mode pulsators. We show that an abundant spectrum of frequencies is achievable across a wide range of magnitudes and co-pointing PLATO cameras. Within the magnitude-limited regimes simulated in this work (G ≲ 14 for γ Doradus stars and G ≲ 16 for SPB stars), the dominant g-mode frequency was recovered in more than 95% of cases. Furthermore, we find that an increased spacecraft noise budget impacts the recovery of g modes more than the stellar contamination by variable stars.Conclusions. MOCKA helps improve our understanding of the limits of the PLATO mission, as well as to highlight the opportunities to push astrophysics beyond current stellar models. All the data products of this paper are made available to the community for further exploration. The key data products of MOCKA can be found include the magnitude-limited Gaia catalogue of the first PLATO pointing field, together with fully reduced light curves from multi-camera observations for each pulsation class.
{"title":"MOCKA – A PLATO mock asteroseismic catalogue: Simulations for gravity-mode oscillators","authors":"N. Jannsen, A. Tkachenko, P. Royer, J. De Ridder, D. Seynaeve, C. Aerts, S. Aigrain, E. Plachy, A. Bodi, M. Uzundag, D. M. Bowman, D. J. Fritzewski, L. W. IJspeert, G. Li, M. G. Pedersen, M. Vanrespaille, T. Van Reeth","doi":"10.1051/0004-6361/202452811","DOIUrl":"https://doi.org/10.1051/0004-6361/202452811","url":null,"abstract":"<i>Context<i/>. With the PLAnetary Transits and Oscillation of stars (PLATO) space mission set for launch in December 2026 by the European Space Agency (ESA), a new photometric legacy and a future of new scientific discoveries await the community. By exploring scientific topics outside of the core science program, the PLATO complementary science program (PLATO-CS) provides a unique opportunity to maximise the scientific yield of the mission.<i>Aims<i/>. In this work, we investigate PLATO’s potential for observing pulsating stars across the Hertzsprung–Russell diagram (HRD). This search is distinct from the core science program. Here, we present a PLATO mock asteroseismic catalogue (MOCKA) of intermediate to massive stars as a benchmark to highlight the asteroseismic yield of PLATO-CS in a quantitative way. MOCKA includes simulations of <i>β<i/> Cephei, slowly pulsating B (SPB), <i>δ<i/> Scuti, <i>γ<i/> Doradus, RR Lyrae, Cepheid, hot sub-dwarf, and white dwarf stars. In particular, main sequence gravity (<i>g<i/>) mode pulsators are of interest, as some of these stars form an important foundation for the scientific calibration of PLATO. Their pulsation modes primarily probe the radiative region near the convective core boundary, making them unique stellar laboratories for studying the deep internal structure of stars.<i>Methods<i/>. MOCKA is based on a magnitude-limited (<i>G<i/> ≲ 17) <i>Gaia<i/> catalogue. It is a product of realistic end-to-end PlatoSim simulations of stars for the first PLATO pointing field in the southern hemisphere, which will be observed for a minimum duration of two years. Comprising a state-of-the-art hare-and-hound detection exercise, the simulations of this project explore the impact of spacecraft systematics and stellar contamination on the on-board PLATO light curves.<i>Results<i/>. We demonstrate, for the first time, PLATO’s ability to detect and recover the oscillation modes for main sequence <i>g<i/>-mode pulsators. We show that an abundant spectrum of frequencies is achievable across a wide range of magnitudes and co-pointing PLATO cameras. Within the magnitude-limited regimes simulated in this work (<i>G<i/> ≲ 14 for <i>γ<i/> Doradus stars and <i>G<i/> ≲ 16 for SPB stars), the dominant g-mode frequency was recovered in more than 95% of cases. Furthermore, we find that an increased spacecraft noise budget impacts the recovery of g modes more than the stellar contamination by variable stars.<i>Conclusions<i/>. MOCKA helps improve our understanding of the limits of the PLATO mission, as well as to highlight the opportunities to push astrophysics beyond current stellar models. All the data products of this paper are made available to the community for further exploration. The key data products of MOCKA can be found include the magnitude-limited <i>Gaia<i/> catalogue of the first PLATO pointing field, together with fully reduced light curves from multi-camera observations for each pulsation class.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"8 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143401493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-12DOI: 10.1051/0004-6361/202452573
G. Costa, K. G. Shepherd, A. Bressan, F. Addari, Y. Chen, X. Fu, G. Volpato, C. T. Nguyen, L. Girardi, P. Marigo, A. Mazzi, G. Pastorelli, M. Trabucchi, D. Bossini, S. Zaggia
Recent advancements in stellar evolution modeling offer unprecedented accuracy in predicting the evolution and deaths of stars. We present new stellar evolutionary models computed with the updated PARSEC V2.0 code for a comprehensive and homogeneous grid of metallicities and initial masses. Nuclear reaction networks, mass loss prescriptions, and the treatment of elemental mixing have all been updated in PARSEC V2.0. We computed models for thirteen initial metallicities spanning Z = 10−11 to Z = 0.03, with masses ranging from 2.0 M⊙ to 2000 M⊙, consisting of a library of over 1100 (∼2100 tracks including pure-He models) full stellar evolution tracks. For each track, the evolution is followed from the pre-main-sequence to the most advanced early-asymptotic-giant-branch or the pre-supernova phases (depending on the stellar mass). Here, we describe the properties of the tracks and their chemical and structural evolution. We computed the final fates and the remnant masses and built the mass spectrum for each metallicity, finding that the combined black hole (BH) pair-instability mass gap spans just between 100 and 130 M⊙. Moreover, the remnant masses provide models consistent with observed BH masses, such as those from the primaries of GW190521, Cygnus X-1, and Gaia BH3 binary systems. We computed and provided the chemical ejecta from stellar winds and explosive final fates, along with the ionizing photon rates. We show how metallicity affects the evolution, fates, ejecta, and ionizing photon counts from these stars. Our results show strong overall consistency with other tracks computed with different codes, and the most significant discrepancies arise for very massive stars (MZAMS > 120 M⊙) due to the different treatment of mixing and mass loss. A comparison with a large sample of observed massive stars in the Tarantula Nebula of the Large Magellanic Cloud shows that our tracks nicely reproduce the majority of stars that lie on the main sequence. All the models are publicly available and can be retrieved in the PARSEC database.
{"title":"Evolutionary tracks, ejecta, and ionizing photons from intermediate-mass to very massive stars with PARSEC⋆","authors":"G. Costa, K. G. Shepherd, A. Bressan, F. Addari, Y. Chen, X. Fu, G. Volpato, C. T. Nguyen, L. Girardi, P. Marigo, A. Mazzi, G. Pastorelli, M. Trabucchi, D. Bossini, S. Zaggia","doi":"10.1051/0004-6361/202452573","DOIUrl":"https://doi.org/10.1051/0004-6361/202452573","url":null,"abstract":"Recent advancements in stellar evolution modeling offer unprecedented accuracy in predicting the evolution and deaths of stars. We present new stellar evolutionary models computed with the updated PARSEC V2.0 code for a comprehensive and homogeneous grid of metallicities and initial masses. Nuclear reaction networks, mass loss prescriptions, and the treatment of elemental mixing have all been updated in PARSEC V2.0. We computed models for thirteen initial metallicities spanning <i>Z<i/> = 10<sup>−11<sup/> to <i>Z<i/> = 0.03, with masses ranging from 2.0 M<sub>⊙<sub/> to 2000 M<sub>⊙<sub/>, consisting of a library of over 1100 (∼2100 tracks including pure-He models) full stellar evolution tracks. For each track, the evolution is followed from the pre-main-sequence to the most advanced early-asymptotic-giant-branch or the pre-supernova phases (depending on the stellar mass). Here, we describe the properties of the tracks and their chemical and structural evolution. We computed the final fates and the remnant masses and built the mass spectrum for each metallicity, finding that the combined black hole (BH) pair-instability mass gap spans just between 100 and 130 M<sub>⊙<sub/>. Moreover, the remnant masses provide models consistent with observed BH masses, such as those from the primaries of GW190521, Cygnus X-1, and <i>Gaia<i/> BH3 binary systems. We computed and provided the chemical ejecta from stellar winds and explosive final fates, along with the ionizing photon rates. We show how metallicity affects the evolution, fates, ejecta, and ionizing photon counts from these stars. Our results show strong overall consistency with other tracks computed with different codes, and the most significant discrepancies arise for very massive stars (<i>M<i/><sub>ZAMS<sub/> > 120 M<sub>⊙<sub/>) due to the different treatment of mixing and mass loss. A comparison with a large sample of observed massive stars in the Tarantula Nebula of the Large Magellanic Cloud shows that our tracks nicely reproduce the majority of stars that lie on the main sequence. All the models are publicly available and can be retrieved in the PARSEC database.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"78 5 Pt 1 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143401494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-12DOI: 10.1051/0004-6361/202452366
A. Ulgiati, S. Paiano, F. Pintore, T. D. Russell, B. Sbarufatti, C. Pinto, E. Ambrosi, A. D’Aì, G. Cusumano, M. Del Santo
Aims. We searched for the multi-wavelength (X-ray, optical, and radio) counterparts to the unassociated gamma-ray sources (UGS) of the Fermi 4FGL-DR4 catalogue. The main goal was to identify new blazars and/or new active galactic nuclei that emit at GeV energies [such as (narrow-line) Seyfert-1 and radio galaxies].Methods. We focused on sky regions that were observed by the Swift satellite and that overlap with the reported positions of the UGSs. Our primary interest are extragalactic sources, and we therefore focused on UGSs that are located outside the Galactic plane (|b|> 10°). Because of the large number of sources (about 1800 UGS), we developed a pipeline to automatise the search for counterparts and significantly reduce the computational time for the analysis. Our association process began by identifying potential X-ray counterparts for each UGS. When one was found, we further searched for corresponding radio and optical counterparts in the X-ray counterpart error box to minimise ambiguities.Results. Out of the 1284 UGSs in the 4FGL-DR4 catalogue, 714 were observed at least once by Swift/X-ray Telescope (Swift/XRT). We detected at least one X-ray source within the Fermi error box with a significance of ≥3σ for 274 of these γ-ray emitters. Of these, 193 UGSs have a single potential X-ray counterpart (referred to as UGS1), while 81 have multiple potential X-ray counterparts within the Fermi error box (referred to as UGS2). Of the UGS2, 54 have two X-ray counterparts, 11 have three, and the remaining 16 have more than three counterparts. Each UGS1 has an optical counterpart, and 113 might also be associated with a radio counterpart. We compared the properties of the possible counterpart with those of the γ-ray emitters identified by Fermi with the aim to assess the goodness of our associations.
{"title":"Search for the multi-wavelength counterparts to extragalactic unassociated Fermi γ-ray sources","authors":"A. Ulgiati, S. Paiano, F. Pintore, T. D. Russell, B. Sbarufatti, C. Pinto, E. Ambrosi, A. D’Aì, G. Cusumano, M. Del Santo","doi":"10.1051/0004-6361/202452366","DOIUrl":"https://doi.org/10.1051/0004-6361/202452366","url":null,"abstract":"<i>Aims.<i/> We searched for the multi-wavelength (X-ray, optical, and radio) counterparts to the unassociated gamma-ray sources (UGS) of the <i>Fermi<i/> 4FGL-DR4 catalogue. The main goal was to identify new blazars and/or new active galactic nuclei that emit at GeV energies [such as (narrow-line) Seyfert-1 and radio galaxies].<i>Methods.<i/> We focused on sky regions that were observed by the <i>Swift<i/> satellite and that overlap with the reported positions of the UGSs. Our primary interest are extragalactic sources, and we therefore focused on UGSs that are located outside the Galactic plane (|<i>b<i/>|> 10°). Because of the large number of sources (about 1800 UGS), we developed a pipeline to automatise the search for counterparts and significantly reduce the computational time for the analysis. Our association process began by identifying potential X-ray counterparts for each UGS. When one was found, we further searched for corresponding radio and optical counterparts in the X-ray counterpart error box to minimise ambiguities.<i>Results.<i/> Out of the 1284 UGSs in the 4FGL-DR4 catalogue, 714 were observed at least once by <i>Swift<i/>/X-ray Telescope (<i>Swift<i/>/XRT). We detected at least one X-ray source within the <i>Fermi<i/> error box with a significance of ≥3<i>σ<i/> for 274 of these <i>γ<i/>-ray emitters. Of these, 193 UGSs have a single potential X-ray counterpart (referred to as UGS1), while 81 have multiple potential X-ray counterparts within the Fermi error box (referred to as UGS2). Of the UGS2, 54 have two X-ray counterparts, 11 have three, and the remaining 16 have more than three counterparts. Each UGS1 has an optical counterpart, and 113 might also be associated with a radio counterpart. We compared the properties of the possible counterpart with those of the <i>γ<i/>-ray emitters identified by <i>Fermi<i/> with the aim to assess the goodness of our associations.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"19 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143401451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-11DOI: 10.1051/0004-6361/202452920
Zehao Zhang, Biwei Jiang, Yi Ren, He Zhao, Ming Yang
Red supergiants (RSGs) are essential to understanding the evolution and the contribution to the interstellar medium of massive stars. However, the number of identified RSGs within the Milky Way is still limited, mainly due to the difficulty of measuring stellar extinction and distance. The release of approximately one million RVS spectra in Gaia DR3 presents a new opportunity for identifying Galactic RSGs because the equivalent width of the calcium triplet lines (EW(CaT)) in the spectra is an excellent indicator of stellar surface gravity. We used RVS spectra with a signal-to-noise ratio (S/N) greater than 100 to search for Galactic RSGs. We removed dwarf stars and red giants and selected RSG candidates based on their location in the EW(CaT) versus BP − RP diagram. Early-type RSG candidates (K0-M2) were then identified using the criteria BP − RP > 1.584 and EW(CaT) > 1.1 nm. The criteria of the average equivalent widths of TiO in the XP spectra (EW(TiO)) > 10 nm, the color index K − W3 < 0.5, and the period-amplitude sequence from the Gaia DR3 LPV catalog were further applied to remove late-type red giants (after M2) and asymptotic giant branch stars. This method yielded 30 early-type (K0-M2) and 6196 late-type (after M2) RSG candidates, which is a significant increase compared to the previous Galactic RSG sample. The application of this approach to spectra with S/N > 50 resulted in 48 early-type and 11 491 late-type RSG candidates. This preliminary analysis paves the way for more extensive research with Gaia DR4, when larger spectral datasets are expected to significantly enhance our understanding of Galactic RSG populations.
{"title":"Searching for Galactic red supergiants with Gaia RVS spectra","authors":"Zehao Zhang, Biwei Jiang, Yi Ren, He Zhao, Ming Yang","doi":"10.1051/0004-6361/202452920","DOIUrl":"https://doi.org/10.1051/0004-6361/202452920","url":null,"abstract":"Red supergiants (RSGs) are essential to understanding the evolution and the contribution to the interstellar medium of massive stars. However, the number of identified RSGs within the Milky Way is still limited, mainly due to the difficulty of measuring stellar extinction and distance. The release of approximately one million RVS spectra in <i>Gaia<i/> DR3 presents a new opportunity for identifying Galactic RSGs because the equivalent width of the calcium triplet lines (EW(CaT)) in the spectra is an excellent indicator of stellar surface gravity. We used RVS spectra with a signal-to-noise ratio (S/N) greater than 100 to search for Galactic RSGs. We removed dwarf stars and red giants and selected RSG candidates based on their location in the EW(CaT) versus <i>BP<i/> − <i>RP<i/> diagram. Early-type RSG candidates (K0-M2) were then identified using the criteria <i>BP<i/> − <i>RP<i/> > 1.584 and EW(CaT) > 1.1 nm. The criteria of the average equivalent widths of TiO in the XP spectra (EW(TiO)) > 10 nm, the color index <i>K<i/> − <i>W<i/>3 < 0.5, and the period-amplitude sequence from the <i>Gaia<i/> DR3 LPV catalog were further applied to remove late-type red giants (after M2) and asymptotic giant branch stars. This method yielded 30 early-type (K0-M2) and 6196 late-type (after M2) RSG candidates, which is a significant increase compared to the previous Galactic RSG sample. The application of this approach to spectra with S/N > 50 resulted in 48 early-type and 11 491 late-type RSG candidates. This preliminary analysis paves the way for more extensive research with <i>Gaia<i/> DR4, when larger spectral datasets are expected to significantly enhance our understanding of Galactic RSG populations.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"60 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-11DOI: 10.1051/0004-6361/202452342
R. Adam, T. Eynard-Machet, I. Bartalucci, D. Cherouvrier, N. Clerc, L. Di Mascolo, S. Dupourqué, C. Ferrari, J.-F. Macías-Pérez, E. Pointecouteau, G. W. Pratt
Turbulent gas motions are expected to dominate the non-thermal energy budget of the intracluster medium (ICM). The measurement of pressure fluctuations from high angular resolution Sunyaev–Zel’dovich imaging opens a new avenue to study ICM turbulence, complementary to X-ray density fluctuation measures. We developed a methodological framework designed to optimally extract information on the ICM pressure fluctuation power spectrum statistics, and publicly released the associated software named PITSZI (Probing ICM Turbulence from Sunyaev–Zel’dovich Imaging). We applied this tool to the New IRAM KIDs Array (NIKA) data of the merging cluster MACS J0717.5+3745 to measure its pressure fluctuation power spectrum at high significance, and to investigate the implications for its non-thermal content. Depending on the choice of the radial pressure model and the details of the applied methodology, we measured an energy injection scale Linj ∼ 800 kpc. The power spectrum normalization corresponds to a characteristic amplitude reaching . These results were obtained assuming that the ICM of MACS J0717.5+3745 can be described as pressure fluctuations on top of a single (smooth) halo, and were dominated by systematics due to the choice of the radial pressure model. Using simulations, we determined that fitting a radial model to the data can suppress the observed fluctuations by up to ∼50%, while a poorly representative radial model can induce spurious fluctuations, which we also quantified. Assuming standard scaling relations between the pressure fluctuations and turbulence, we find that MACS J0717.5+3745 presents a turbulent velocity dispersion σv ∼ 1200 km/s, a kinetic to kinetic plus thermal pressure fraction Pkin/Pkin + th ∼ 20%, and we estimate the hydrostatic mass bias to bHSE ∼ 0.3 − 0.4. Our results are in excellent agreement with alternative measurements obtained from X-ray surface brightness fluctuations, and in agreement with the fluctuations being adiabatic in nature.
{"title":"PITSZI: Probing intra-cluster medium turbulence with Sunyaev–Zel’dovich imaging","authors":"R. Adam, T. Eynard-Machet, I. Bartalucci, D. Cherouvrier, N. Clerc, L. Di Mascolo, S. Dupourqué, C. Ferrari, J.-F. Macías-Pérez, E. Pointecouteau, G. W. Pratt","doi":"10.1051/0004-6361/202452342","DOIUrl":"https://doi.org/10.1051/0004-6361/202452342","url":null,"abstract":"Turbulent gas motions are expected to dominate the non-thermal energy budget of the intracluster medium (ICM). The measurement of pressure fluctuations from high angular resolution Sunyaev–Zel’dovich imaging opens a new avenue to study ICM turbulence, complementary to X-ray density fluctuation measures. We developed a methodological framework designed to optimally extract information on the ICM pressure fluctuation power spectrum statistics, and publicly released the associated software named PITSZI (Probing ICM Turbulence from Sunyaev–Zel’dovich Imaging). We applied this tool to the New IRAM KIDs Array (NIKA) data of the merging cluster MACS J0717.5+3745 to measure its pressure fluctuation power spectrum at high significance, and to investigate the implications for its non-thermal content. Depending on the choice of the radial pressure model and the details of the applied methodology, we measured an energy injection scale <i>L<i/><sub>inj<sub/> ∼ 800 kpc. The power spectrum normalization corresponds to a characteristic amplitude reaching . These results were obtained assuming that the ICM of MACS J0717.5+3745 can be described as pressure fluctuations on top of a single (smooth) halo, and were dominated by systematics due to the choice of the radial pressure model. Using simulations, we determined that fitting a radial model to the data can suppress the observed fluctuations by up to ∼50%, while a poorly representative radial model can induce spurious fluctuations, which we also quantified. Assuming standard scaling relations between the pressure fluctuations and turbulence, we find that MACS J0717.5+3745 presents a turbulent velocity dispersion <i>σ<i/><sub><i>v<i/><sub/> ∼ 1200 km/s, a kinetic to kinetic plus thermal pressure fraction <i>P<i/><sub>kin<sub/>/<i>P<i/><sub>kin + th<sub/> ∼ 20%, and we estimate the hydrostatic mass bias to <i>b<i/><sub>HSE<sub/> ∼ 0.3 − 0.4. Our results are in excellent agreement with alternative measurements obtained from X-ray surface brightness fluctuations, and in agreement with the fluctuations being adiabatic in nature.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"55 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-11DOI: 10.1051/0004-6361/202452859
W. Mulder, S. de Regt, R. Landman, D. González Picos, I. A. G. Snellen, Y. Zhang, S. Gandhi, C. Ginski, A. Y. Kesseli, E. Nasedkin, T. Stolker
Context. Recent research suggests that the distinct formation processes of exoplanets and brown dwarfs may have an influence on the chemical and isotopic composition of their atmospheres. Variations in the carbon 12C/13C isotope ratio have been observed and tentatively linked to the top-down formation of brown dwarfs and the core accretion pathway of super-Jupiters. The ESO SupJup Survey, conducted with CRIRES+ on the Very Large Telescope, aims to characterise the atmospheres of young brown dwarfs and super-Jupiters, specifically by investigating the 12C/13C ratio as a tracer of their formation pathways.Aims. We present the atmospheric characterisation of three isolated L-type brown dwarfs (2MASS J08354256-0819237, 2MASS J05012406-0010452, and 2MASS J05002100+0330501) included in the ESO SupJup Survey. We aim to constrain the C/O and 12C/13C ratios, and investigate whether the oxygen 16O/18O isotope ratio can be probed.Methods. We analysed the CRIRES+ K-band spectra of the three targets using our atmospheric retrieval framework. This framework couples the radiative transfer code petitRADTRANS with the sampling algorithm MultiNest.Results. We report 12C/13C ratios of 89−11+11 and 117−17+20 for J0835 and J0500 with strong 13CO significance (>6.5σ) and a tentative (3σ) detection of 13CO for J0501, resulting in a carbon isotope ratio of 155−53+56. Only a weak detection of the H218O isotope was found in J0835. The C/O ratios are found to be in the range 0.65 to 0.71 for the three targets, and all exhibit strong detections of HF.Conclusions. The 12C/13C ratios appear to be higher than that of the interstellar medium.
{"title":"The ESO SupJup Survey","authors":"W. Mulder, S. de Regt, R. Landman, D. González Picos, I. A. G. Snellen, Y. Zhang, S. Gandhi, C. Ginski, A. Y. Kesseli, E. Nasedkin, T. Stolker","doi":"10.1051/0004-6361/202452859","DOIUrl":"https://doi.org/10.1051/0004-6361/202452859","url":null,"abstract":"<i>Context<i/>. Recent research suggests that the distinct formation processes of exoplanets and brown dwarfs may have an influence on the chemical and isotopic composition of their atmospheres. Variations in the carbon <sup>12<sup/>C/<sup>13<sup/>C isotope ratio have been observed and tentatively linked to the top-down formation of brown dwarfs and the core accretion pathway of super-Jupiters. The ESO SupJup Survey, conducted with CRIRES+ on the Very Large Telescope, aims to characterise the atmospheres of young brown dwarfs and super-Jupiters, specifically by investigating the <sup>12<sup/>C/<sup>13<sup/>C ratio as a tracer of their formation pathways.<i>Aims.<i/> We present the atmospheric characterisation of three isolated L-type brown dwarfs (2MASS J08354256-0819237, 2MASS J05012406-0010452, and 2MASS J05002100+0330501) included in the ESO SupJup Survey. We aim to constrain the C/O and <sup>12<sup/>C/<sup>13<sup/>C ratios, and investigate whether the oxygen <sup>16<sup/>O/<sup>18<sup/>O isotope ratio can be probed.<i>Methods.<i/> We analysed the CRIRES+ <i>K<i/>-band spectra of the three targets using our atmospheric retrieval framework. This framework couples the radiative transfer code petitRADTRANS with the sampling algorithm MultiNest.<i>Results.<i/> We report <sup>12<sup/>C/<sup>13<sup/>C ratios of 89<sub>−11<sub/><sup>+11<sup/> and 117<sub>−17<sub/><sup>+20<sup/> for J0835 and J0500 with strong <sup>13<sup/>CO significance (>6.5<i>σ<i/>) and a tentative (3<i>σ<i/>) detection of <sup>13<sup/>CO for J0501, resulting in a carbon isotope ratio of 155<sub>−53<sub/><sup>+56<sup/>. Only a weak detection of the H<sub>2<sub/><sup>18<sup/>O isotope was found in J0835. The C/O ratios are found to be in the range 0.65 to 0.71 for the three targets, and all exhibit strong detections of HF.<i>Conclusions.<i/> The <sup>12<sup/>C/<sup>13<sup/>C ratios appear to be higher than that of the interstellar medium.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"32 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-11DOI: 10.1051/0004-6361/202347275
Th. Rivinius, R. Klement, S. D. Chojnowski, D. Baade, M. Abdul-Masih, N. Przybilla, J. Guarro Fló, B. Heathcote, P. Hadrava, D. Gies, K. Shepard, C. Buil, O. Garde, O. Thizy, J. D. Monnier, N. Anugu, C. Lanthermann, G. Schaefer, C. Davies, S. Kraus, J. Ennis, B. R. Setterholm, T. Gardner, N. Ibrahim, S. Chhabra, M. Gutierrez, I. Codron
<i>Context.<i/> Many classical Be stars acquire their very rapid rotation by mass- and angular-momentum transfer in massive binaries, marking the first phase of the evolutionary chain. Later-stage products, such as Be+subdwarf- and Be+neutron-star binaries (Be X-ray binaries), are also well known, although the search for definitive proof of Be+white dwarf companions is ongoing. Short-lived intermediate-phase objects, that is, binaries past the interaction stage but with a donor star that has not yet reached the end of its evolution or contraction, have only recently been discovered.<i>Aims.<i/> The main hallmark of this kind of binary is a system of absorption lines with low width, significant radial-velocity variations, and peculiar relative line strengths. Data archives and the literature can be searched for additional candidates exhibiting this pattern, and follow-up observations can be obtained in order to increase the number of these systems with quantitatively known orbits, providing a basis for an initial statistical investigation and to develop observational strategies for abundance analyses.<i>Methods.<i/> We identified 13 candidates at various confidence levels. To verify their nature, we derived orbital elements from new high-quality spectra and interferometric observations where possible. We also performed qualitative analyses of other basic parameters, and preliminarily evaluated indicators of advanced stages of nucleosynthesis.<i>Results.<i/> Adding to the two known systems identified as classical Be star+pre-subdwarf binaries (LB-1 and HR 6819), we confirm two more (V742 Cas, HD 44637) with interferometry, with V742 Cas setting a new record for the smallest visually observed angular semi-major axis, at <i>a<i/> = 0.663 mas. Two further systems (V447 Sct, V1362 Cyg) are not resolved interferometrically, but other evidence puts them at the same confidence level as LB-1. V2174 Cyg is a candidate with very high confidence, but was not observed interferometrically. The remaining systems are either candidates with varying levels of confidence –mainly due to the lack of available spectroscopic or interferometric observations for comparison with the others and orbit determination– or could be rejected as candidates with the followup observations.<i>Conclusions.<i/> Of a mostly magnitude-complete sample of 328 Be stars, 0.5–1% are found to have recently completed the mass overflow that led to their formation. Another 5% are systems with a compact subdwarf companion –that is, they are further evolved after a previous overflow– and a further 2% possibly harbor white dwarfs. All these systems are early B subtypes, but if the original sample is restricted to early subtypes (136 objects), these percentages increase by a factor of about 2.5, while dropping to zero for the mid and late subtypes (together 204 objects). This strongly suggests that early-type versus mid- and late-type Be stars follow differently weighted channels to acquire their rap
{"title":"Newborn Be star systems observed shortly after mass transfer","authors":"Th. Rivinius, R. Klement, S. D. Chojnowski, D. Baade, M. Abdul-Masih, N. Przybilla, J. Guarro Fló, B. Heathcote, P. Hadrava, D. Gies, K. Shepard, C. Buil, O. Garde, O. Thizy, J. D. Monnier, N. Anugu, C. Lanthermann, G. Schaefer, C. Davies, S. Kraus, J. Ennis, B. R. Setterholm, T. Gardner, N. Ibrahim, S. Chhabra, M. Gutierrez, I. Codron","doi":"10.1051/0004-6361/202347275","DOIUrl":"https://doi.org/10.1051/0004-6361/202347275","url":null,"abstract":"<i>Context.<i/> Many classical Be stars acquire their very rapid rotation by mass- and angular-momentum transfer in massive binaries, marking the first phase of the evolutionary chain. Later-stage products, such as Be+subdwarf- and Be+neutron-star binaries (Be X-ray binaries), are also well known, although the search for definitive proof of Be+white dwarf companions is ongoing. Short-lived intermediate-phase objects, that is, binaries past the interaction stage but with a donor star that has not yet reached the end of its evolution or contraction, have only recently been discovered.<i>Aims.<i/> The main hallmark of this kind of binary is a system of absorption lines with low width, significant radial-velocity variations, and peculiar relative line strengths. Data archives and the literature can be searched for additional candidates exhibiting this pattern, and follow-up observations can be obtained in order to increase the number of these systems with quantitatively known orbits, providing a basis for an initial statistical investigation and to develop observational strategies for abundance analyses.<i>Methods.<i/> We identified 13 candidates at various confidence levels. To verify their nature, we derived orbital elements from new high-quality spectra and interferometric observations where possible. We also performed qualitative analyses of other basic parameters, and preliminarily evaluated indicators of advanced stages of nucleosynthesis.<i>Results.<i/> Adding to the two known systems identified as classical Be star+pre-subdwarf binaries (LB-1 and HR 6819), we confirm two more (V742 Cas, HD 44637) with interferometry, with V742 Cas setting a new record for the smallest visually observed angular semi-major axis, at <i>a<i/> = 0.663 mas. Two further systems (V447 Sct, V1362 Cyg) are not resolved interferometrically, but other evidence puts them at the same confidence level as LB-1. V2174 Cyg is a candidate with very high confidence, but was not observed interferometrically. The remaining systems are either candidates with varying levels of confidence –mainly due to the lack of available spectroscopic or interferometric observations for comparison with the others and orbit determination– or could be rejected as candidates with the followup observations.<i>Conclusions.<i/> Of a mostly magnitude-complete sample of 328 Be stars, 0.5–1% are found to have recently completed the mass overflow that led to their formation. Another 5% are systems with a compact subdwarf companion –that is, they are further evolved after a previous overflow– and a further 2% possibly harbor white dwarfs. All these systems are early B subtypes, but if the original sample is restricted to early subtypes (136 objects), these percentages increase by a factor of about 2.5, while dropping to zero for the mid and late subtypes (together 204 objects). This strongly suggests that early-type versus mid- and late-type Be stars follow differently weighted channels to acquire their rap","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"16 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-11DOI: 10.1051/0004-6361/202452188
P. Ventura, S. Tosi, D. A. García-Hernández, F. Dell’Agli, D. Kamath, L. Stanghellini, S. Bianchi, M. Tailo, M. A. Gómez-Muñoz
Context. The study of planetary nebulae (PNe) offers the opportunity to evaluate the efficiency of the dust production mechanism during the very late asymptotic giant branch (AGB) phases, which allows us to assess the role played by AGB stars as dust manufacturers.Aims. We studied the relationship between the properties of PNe, particularly the gas and dust content, and the mass and metallicity of the progenitor stars to understand how dust production works in the late AGB phases and to shed new light on the physical processes the stars and the material in their surroundings are subject to in the period between the departure from the AGB and the start of the PN phase.Methods. We considered a sample of nine PNe in the Large Magellanic Cloud, seven of which are characterised by the presence of carbonaceous dust and the remaining two the presence of silicates. For these stars, we estimated the masses and the metallicity of their progenitor stars. We combined results from stellar evolution and dust formation modelling with results from analyses of the spectral energy distribution to determine the relation between the dust and gas mass of the PNe considered and the mass and metallicity of the progenitors.Results. The physical properties of carbon-rich PNe are influenced by the mass of the progenitor star. Specifically, the dust-to-gas ratio in the nebula increases from 5 × 10−4 to 6 × 10−3 as the progenitor star’s mass increases from approximately 0.9–2 M⊙. This change is partly influenced by the effective temperature of the PNe, and it occurs because higher-mass carbon stars are more efficient at producing dust. Consequently, as the progenitor’s mass increases, the gas mass of the PN decreases since the larger amounts of dust lead to greater effects from radiation pressure, which pushes the gas outwards. No meaningful conclusions can be drawn from the study of the PNe with silicate-type dust, because the subsample comprises two PNe only, one of which is almost dust-free.
{"title":"Planetary nebulae of the Large Magellanic Cloud","authors":"P. Ventura, S. Tosi, D. A. García-Hernández, F. Dell’Agli, D. Kamath, L. Stanghellini, S. Bianchi, M. Tailo, M. A. Gómez-Muñoz","doi":"10.1051/0004-6361/202452188","DOIUrl":"https://doi.org/10.1051/0004-6361/202452188","url":null,"abstract":"<i>Context.<i/> The study of planetary nebulae (PNe) offers the opportunity to evaluate the efficiency of the dust production mechanism during the very late asymptotic giant branch (AGB) phases, which allows us to assess the role played by AGB stars as dust manufacturers.<i>Aims.<i/> We studied the relationship between the properties of PNe, particularly the gas and dust content, and the mass and metallicity of the progenitor stars to understand how dust production works in the late AGB phases and to shed new light on the physical processes the stars and the material in their surroundings are subject to in the period between the departure from the AGB and the start of the PN phase.<i>Methods.<i/> We considered a sample of nine PNe in the Large Magellanic Cloud, seven of which are characterised by the presence of carbonaceous dust and the remaining two the presence of silicates. For these stars, we estimated the masses and the metallicity of their progenitor stars. We combined results from stellar evolution and dust formation modelling with results from analyses of the spectral energy distribution to determine the relation between the dust and gas mass of the PNe considered and the mass and metallicity of the progenitors.<i>Results.<i/> The physical properties of carbon-rich PNe are influenced by the mass of the progenitor star. Specifically, the dust-to-gas ratio in the nebula increases from 5 × 10<sup>−4<sup/> to 6 × 10<sup>−3<sup/> as the progenitor star’s mass increases from approximately 0.9–2 M<sub>⊙<sub/>. This change is partly influenced by the effective temperature of the PNe, and it occurs because higher-mass carbon stars are more efficient at producing dust. Consequently, as the progenitor’s mass increases, the gas mass of the PN decreases since the larger amounts of dust lead to greater effects from radiation pressure, which pushes the gas outwards. No meaningful conclusions can be drawn from the study of the PNe with silicate-type dust, because the subsample comprises two PNe only, one of which is almost dust-free.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"4 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-11DOI: 10.1051/0004-6361/202452066
S. Mathis
Context. Internal gravity waves (IGWs) are one of the mechanisms that can play a key role in efficiently redistributing angular momentum in stars along their evolution. The study of IGWs is thus of major importance since space-based asteroseismology reveals a transport of angular momentum in stars, which is stronger by two orders of magnitude than the one predicted by stellar models ignoring their action or those of magnetic fields.Aims. IGWs trigger angular momentum transport when they are damped by heat or viscous diffusion, when they meet a critical layer where their phase velocity in the azimuthal direction equals the zonal wind or when they break. Theoretical prescriptions have been derived for the transport of angular momentum induced by IGWs because of their radiative and viscous dampings and of the critical layers they encounter along their propagation. However, none have been proposed for the transport of angular momentum triggered by their non-linear breaking. In this work, we aim to derive such a physical and robust prescription, which can be implemented in stellar structure and evolution codes.Methods. We adapted an analytical saturation model – which has been developed for IGWs’ nonlinear convective breaking in the Earth’s atmosphere and has been successfully compared to in situ measurements in the stratosphere – to the case of deep spherical stellar interiors. This allowed us to derive the saturated amplitude of the velocity of IGWs breaking in stellar radiation zones through convective overturning of the stable stratification or the instability of the vertical shear of IGWs motion and of the angular momentum transport they trigger. In a first step, we neglected the modification of IGWs by the Coriolis acceleration and the Lorentz force, which are discussed and taken into account in a second step.Results. We derive a complete semi-analytical prescription for the transport of angular momentum by IGWs that takes into account both their radiative damping and their potential nonlinear breaking because of their convective and vertical shear instabilities. We show that the deposit of angular momentum by breaking waves increases with their latitudinal degree, the ratio of the Brunt-Vaïsälä frequency and the wave frequency; and when the density decreases or the Doppler-shifted frequency vanishes. This allows us to bring the physical prescription for the interactions between IGWs and the differential rotation to the same level of realism as the one used in global circulation models for the atmosphere.
{"title":"Non-linear internal waves breaking in stellar-radiation zones","authors":"S. Mathis","doi":"10.1051/0004-6361/202452066","DOIUrl":"https://doi.org/10.1051/0004-6361/202452066","url":null,"abstract":"<i>Context.<i/> Internal gravity waves (IGWs) are one of the mechanisms that can play a key role in efficiently redistributing angular momentum in stars along their evolution. The study of IGWs is thus of major importance since space-based asteroseismology reveals a transport of angular momentum in stars, which is stronger by two orders of magnitude than the one predicted by stellar models ignoring their action or those of magnetic fields.<i>Aims.<i/> IGWs trigger angular momentum transport when they are damped by heat or viscous diffusion, when they meet a critical layer where their phase velocity in the azimuthal direction equals the zonal wind or when they break. Theoretical prescriptions have been derived for the transport of angular momentum induced by IGWs because of their radiative and viscous dampings and of the critical layers they encounter along their propagation. However, none have been proposed for the transport of angular momentum triggered by their non-linear breaking. In this work, we aim to derive such a physical and robust prescription, which can be implemented in stellar structure and evolution codes.<i>Methods.<i/> We adapted an analytical saturation model – which has been developed for IGWs’ nonlinear convective breaking in the Earth’s atmosphere and has been successfully compared to in situ measurements in the stratosphere – to the case of deep spherical stellar interiors. This allowed us to derive the saturated amplitude of the velocity of IGWs breaking in stellar radiation zones through convective overturning of the stable stratification or the instability of the vertical shear of IGWs motion and of the angular momentum transport they trigger. In a first step, we neglected the modification of IGWs by the Coriolis acceleration and the Lorentz force, which are discussed and taken into account in a second step.<i>Results.<i/> We derive a complete semi-analytical prescription for the transport of angular momentum by IGWs that takes into account both their radiative damping and their potential nonlinear breaking because of their convective and vertical shear instabilities. We show that the deposit of angular momentum by breaking waves increases with their latitudinal degree, the ratio of the Brunt-Vaïsälä frequency and the wave frequency; and when the density decreases or the Doppler-shifted frequency vanishes. This allows us to bring the physical prescription for the interactions between IGWs and the differential rotation to the same level of realism as the one used in global circulation models for the atmosphere.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"2 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-11DOI: 10.1051/0004-6361/202449384
A. M. van Genderen, A. Lobel, R. Timmerman, E. R. Deul, A. Vos, H. Nieuwenhuijzen, E. J. van Ballegoij, M. Sblewski, G. W. Henry, E. Blown, G. Di Scala
In this predominantly photometric study, we investigate various types of photometric and physical instabilities in the yellow hypergiant (YHG) <i>ρ<i/> Cas as well as its evolution between 1885 and 2023. The second yellow hypergiant we study is YHG HR 8752, which recently became stable. The other two yellow hypergiants are HR 5171A and HD 179821. We constructed temperature calibration relations based on <i>T<i/><sub>eff<sub/> and simultaneously observed <i>B<i/><i>V<i/> photometry, which exclusively for <i>ρ<i/> Cas enabled us to discuss dependencies between <i>T<i/><sub>eff<sub/> and the selective continuum opacity variations in <i>B<i/> and <i>V<i/>. An important goal of ours was to find correlations between various variable astrophysical parameters and the onset of recurring outburst events. The latter events also represent a stellar pulsation, but of a quite different type than the ordinary stellar pulsations. We present an in-depth photometric analysis of the unsteady long-term variations (LTV) of the median (<i>B<i/> − <i>V<i/>)<sub>obs<sub/> of all ordinary pulsations and the outbursts of <i>ρ<i/> Cas between 1962 and 2020. For this purpose, we introduce a new photometric parameter as well as four new temperature calibration relations. They improve our understanding of the photometric and physical properties of the outburst events and of ordinary pulsation sequences and reveal clear correlations between <i>T<i/><sub>eff<sub/> and the variability in the selective continuum opacity. In the Appendices we also discuss HR 5171A and HD 179821 as well as a number of arresting features observed in HR 8752, which became a stable star between 1996 and 2017. The construction of four temperature calibration relations based on available <i>T<i/><sub>eff<sub/> values and simultaneously observed <i>B<i/><i>V<i/> parameters was essential and so was the introduction of a new photometric parameter for measuring selective continuum opacities. We discuss the improved insight into the dependencies between <i>T<i/><sub>eff<sub/>, the selective continuum opacity, and the (<i>B<i/> − <i>V<i/>)<sub>obs<sub/> variability. We locate <i>ρ<i/> Cas in the Hertzsprung–Russell diagram (HRD) and visualize the selection of cyclic tracks during its ordinary pulsations and outburst events. Next, we present the highlights of our research results through a four-paneled diagram representing the correlations between variations in <i>T<i/><sub>eff<sub/>/selective continuum opacity, the median (<i>B<i/> − <i>V<i/>)<sub>obs<sub/>, and the stellar radius as well as the trends in the ordinary quasi-periods, which include the onset of outbursts. The derived minimum and maximum photospheric radii of <i>ρ<i/> Cas during the outbursts of 1986, 2000, and 2013 agree within estimated errors with the radii during the 2000 outburst measured from distance independent radial velocity observations. This underlines the reliability of our new temperature calibration relations. Based on an analysis
{"title":"Investigation of the pulsations, outbursts, and evolution of the yellow hypergiants","authors":"A. M. van Genderen, A. Lobel, R. Timmerman, E. R. Deul, A. Vos, H. Nieuwenhuijzen, E. J. van Ballegoij, M. Sblewski, G. W. Henry, E. Blown, G. Di Scala","doi":"10.1051/0004-6361/202449384","DOIUrl":"https://doi.org/10.1051/0004-6361/202449384","url":null,"abstract":"In this predominantly photometric study, we investigate various types of photometric and physical instabilities in the yellow hypergiant (YHG) <i>ρ<i/> Cas as well as its evolution between 1885 and 2023. The second yellow hypergiant we study is YHG HR 8752, which recently became stable. The other two yellow hypergiants are HR 5171A and HD 179821. We constructed temperature calibration relations based on <i>T<i/><sub>eff<sub/> and simultaneously observed <i>B<i/><i>V<i/> photometry, which exclusively for <i>ρ<i/> Cas enabled us to discuss dependencies between <i>T<i/><sub>eff<sub/> and the selective continuum opacity variations in <i>B<i/> and <i>V<i/>. An important goal of ours was to find correlations between various variable astrophysical parameters and the onset of recurring outburst events. The latter events also represent a stellar pulsation, but of a quite different type than the ordinary stellar pulsations. We present an in-depth photometric analysis of the unsteady long-term variations (LTV) of the median (<i>B<i/> − <i>V<i/>)<sub>obs<sub/> of all ordinary pulsations and the outbursts of <i>ρ<i/> Cas between 1962 and 2020. For this purpose, we introduce a new photometric parameter as well as four new temperature calibration relations. They improve our understanding of the photometric and physical properties of the outburst events and of ordinary pulsation sequences and reveal clear correlations between <i>T<i/><sub>eff<sub/> and the variability in the selective continuum opacity. In the Appendices we also discuss HR 5171A and HD 179821 as well as a number of arresting features observed in HR 8752, which became a stable star between 1996 and 2017. The construction of four temperature calibration relations based on available <i>T<i/><sub>eff<sub/> values and simultaneously observed <i>B<i/><i>V<i/> parameters was essential and so was the introduction of a new photometric parameter for measuring selective continuum opacities. We discuss the improved insight into the dependencies between <i>T<i/><sub>eff<sub/>, the selective continuum opacity, and the (<i>B<i/> − <i>V<i/>)<sub>obs<sub/> variability. We locate <i>ρ<i/> Cas in the Hertzsprung–Russell diagram (HRD) and visualize the selection of cyclic tracks during its ordinary pulsations and outburst events. Next, we present the highlights of our research results through a four-paneled diagram representing the correlations between variations in <i>T<i/><sub>eff<sub/>/selective continuum opacity, the median (<i>B<i/> − <i>V<i/>)<sub>obs<sub/>, and the stellar radius as well as the trends in the ordinary quasi-periods, which include the onset of outbursts. The derived minimum and maximum photospheric radii of <i>ρ<i/> Cas during the outbursts of 1986, 2000, and 2013 agree within estimated errors with the radii during the 2000 outburst measured from distance independent radial velocity observations. This underlines the reliability of our new temperature calibration relations. Based on an analysis","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"65 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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