Pub Date : 2025-03-20DOI: 10.1051/0004-6361/202453345
J. Vandersnickt, M. Fabry
Context. Massive contact binaries are both stellar-merger and gravitational-wave progenitors, but their evolution is still uncertain. An open problem in the population synthesis of massive contact binaries is the predicted mass ratio distribution. Current simulations evolve quickly to mass ratios close to unity, which is not supported by the sample of observed systems. It has been shown that modifying the near core mixing properties of massive stars can alter the evolution of contact binaries, but this has not been tested on a whole population.Aims. We implement a prescription of the convective core overshooting based on the molecular gradient. The goal of the implementation is to limit the rejuvenation efficiency of the accretor. We aim to investigate the effects of the reduced rejuvenation on the mass ratio distribution of massive contact binaries.Methods. We calculated a grid of 4896 models using the binary-evolution code MESA with our convective overshoot formulation, and we compared the simulations with the known observations of massive contact binaries.Results. We find that by limiting core rejuvenation through the convective core overshoot, the predicted mass ratio distribution shifts significantly to values away from unity. This improves the theoretical predictions of the mass ratios of massive contact binaries.Conclusions. The core rejuvenation of the components in massive contact binaries is a key parameter for their predicted mass ratio distribution. Establishing the rejuvenation efficiency within the contact binary population should therefore be possible. The sample size and uncertainties associated with the characterization of contact binaries, however, prevents us from doing so, and other methods like asteroseismology can place constraints on the rejuvenation process.
{"title":"Effects of limited core rejuvenation on the properties of massive contact binaries","authors":"J. Vandersnickt, M. Fabry","doi":"10.1051/0004-6361/202453345","DOIUrl":"https://doi.org/10.1051/0004-6361/202453345","url":null,"abstract":"<i>Context.<i/> Massive contact binaries are both stellar-merger and gravitational-wave progenitors, but their evolution is still uncertain. An open problem in the population synthesis of massive contact binaries is the predicted mass ratio distribution. Current simulations evolve quickly to mass ratios close to unity, which is not supported by the sample of observed systems. It has been shown that modifying the near core mixing properties of massive stars can alter the evolution of contact binaries, but this has not been tested on a whole population.<i>Aims.<i/> We implement a prescription of the convective core overshooting based on the molecular gradient. The goal of the implementation is to limit the rejuvenation efficiency of the accretor. We aim to investigate the effects of the reduced rejuvenation on the mass ratio distribution of massive contact binaries.<i>Methods.<i/> We calculated a grid of 4896 models using the binary-evolution code MESA with our convective overshoot formulation, and we compared the simulations with the known observations of massive contact binaries.<i>Results.<i/> We find that by limiting core rejuvenation through the convective core overshoot, the predicted mass ratio distribution shifts significantly to values away from unity. This improves the theoretical predictions of the mass ratios of massive contact binaries.<i>Conclusions.<i/> The core rejuvenation of the components in massive contact binaries is a key parameter for their predicted mass ratio distribution. Establishing the rejuvenation efficiency within the contact binary population should therefore be possible. The sample size and uncertainties associated with the characterization of contact binaries, however, prevents us from doing so, and other methods like asteroseismology can place constraints on the rejuvenation process.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"10 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143666081","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 : 2025-03-20DOI: 10.1051/0004-6361/202452374
Saimurali Kolupuri, Roberto Decarli, Roberto Neri, Pierre Cox, Carl Ferkinhoff, Frank Bertoldi, Axel Weiss, Bram P. Venemans, Dominik A. Riechers, Emanuele Paolo Farina, Fabian Walter
We present [NII] 205 μm fine structure line observations of three submillimeter galaxies (SMGs) and three quasar host galaxies (QSOs) at 4 ≲ z ≲ 6 using the Institut de radioastronomie millimétrique (IRAM) interferometer. The [NII] emission is detected in three sources, and we report detections of the underlying dust continuum emission in all sources. The observed [NII]-to-infrared luminosity ratio spans at least 0.5 dex for our sources. Comparing our estimates with sources detected in the [NII] 205 μm at similar redshifts shows that the overall [NII]-to-IR luminosity ratio spans over 1 dex in magnitude from L[NII]/LIR ∼ 10−4–10−5 and follows the trend of the so-called [NII] fine structure line deficit observed in (ultra)-luminous IR galaxies in the local Universe. The [CII]-to-[NII] luminosity ratio is greater than ten for most of our sources, indicating that the bulk of the [CII] 158 μm line emission (f([CII]PDR) > 75%) arises from the neutral medium. From our analysis, we do not find significant differences in the [NII] 205 μm emission and the respective ratios between SMGs and QSOs, suggesting a negligible contribution to the boosting of [NII] 205 μm emission due to the active galactic nucleus (AGN) photoionization. Future investigations involving other fine structure lines and optical diagnostics will provide further insight into a suite of ionized medium properties and reveal the diversity between AGN and non-AGN environments.
{"title":"The [NII] 205 μm line emission from high-z submillimeter galaxies and quasar host galaxies","authors":"Saimurali Kolupuri, Roberto Decarli, Roberto Neri, Pierre Cox, Carl Ferkinhoff, Frank Bertoldi, Axel Weiss, Bram P. Venemans, Dominik A. Riechers, Emanuele Paolo Farina, Fabian Walter","doi":"10.1051/0004-6361/202452374","DOIUrl":"https://doi.org/10.1051/0004-6361/202452374","url":null,"abstract":"We present [NII] 205 μm fine structure line observations of three submillimeter galaxies (SMGs) and three quasar host galaxies (QSOs) at 4 ≲ <i>z<i/> ≲ 6 using the Institut de radioastronomie millimétrique (IRAM) interferometer. The [NII] emission is detected in three sources, and we report detections of the underlying dust continuum emission in all sources. The observed [NII]-to-infrared luminosity ratio spans at least 0.5 dex for our sources. Comparing our estimates with sources detected in the [NII] 205 μm at similar redshifts shows that the overall [NII]-to-IR luminosity ratio spans over 1 dex in magnitude from <i>L<i/><sub>[NII]<sub/>/<i>L<i/><sub>IR<sub/> ∼ 10<sup>−4<sup/>–10<sup>−5<sup/> and follows the trend of the so-called [NII] fine structure line deficit observed in (ultra)-luminous IR galaxies in the local Universe. The [CII]-to-[NII] luminosity ratio is greater than ten for most of our sources, indicating that the bulk of the [CII] 158 μm line emission (<i>f<i/>([CII]<sup>PDR<sup/>) > 75%) arises from the neutral medium. From our analysis, we do not find significant differences in the [NII] 205 μm emission and the respective ratios between SMGs and QSOs, suggesting a negligible contribution to the boosting of [NII] 205 μm emission due to the active galactic nucleus (AGN) photoionization. Future investigations involving other fine structure lines and optical diagnostics will provide further insight into a suite of ionized medium properties and reveal the diversity between AGN and non-AGN environments.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"15 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143666082","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 : 2025-03-19DOI: 10.1051/0004-6361/202452749
H. Mitani, R. Nakatani, R. Kuiper
Extreme-ultraviolet (EUV) driven atmospheric escape is a key process in the atmospheric evolution of close-in exoplanets. In many evolutionary models, an energy-limited mass-loss rate with a constant efficiency (typically ∼10%) is assumed for calculating the mass-loss rate. However, hydrodynamic simulations have demonstrated that this efficiency depends on various stellar and planetary parameters. Comprehending the underlying physics of the efficiency is essential for understanding planetary atmospheric evolution and recent observations of the upper atmosphere of close-in exoplanets. We introduce relevant temperatures and timescales derived from physical principles to elucidate the mass-loss process. Our analytical mass-loss model is based on phenomenology and consistent across a range of planetary parameters. We compared our mass-loss efficiency with that of radiation hydrodynamic simulations, finding that our model can predict efficiency in both energy-limited and recombination-limited regimes. We further applied our model to exoplanets observed with hydrogen absorption (Lyα and Hα). Our findings suggest that Lyα absorption is detectable in planets subjected to intermediate EUV flux; under these conditions, the escaping outflow is insufficient in low-EUV environments, while the photoionization timescale remains short in high EUV ranges. Conversely, Hα absorption is detectable under high-EUV-flux conditions, facilitated by the intense Lyα flux exciting hydrogen atoms. According to our model, the non-detection of neutral hydrogen can be explained by a low mass-loss rate and is not necessarily due to stellar wind confinement or the absence of a hydrogen-dominated atmosphere in many cases. This model can help identify future observational targets and explicates the unusual absorption detection/non-detection patterns observed in recent studies.
{"title":"Physically motivated analytic model of energy efficiency for extreme-ultraviolet-driven atmospheric escape of close-in exoplanets","authors":"H. Mitani, R. Nakatani, R. Kuiper","doi":"10.1051/0004-6361/202452749","DOIUrl":"https://doi.org/10.1051/0004-6361/202452749","url":null,"abstract":"Extreme-ultraviolet (EUV) driven atmospheric escape is a key process in the atmospheric evolution of close-in exoplanets. In many evolutionary models, an energy-limited mass-loss rate with a constant efficiency (typically ∼10%) is assumed for calculating the mass-loss rate. However, hydrodynamic simulations have demonstrated that this efficiency depends on various stellar and planetary parameters. Comprehending the underlying physics of the efficiency is essential for understanding planetary atmospheric evolution and recent observations of the upper atmosphere of close-in exoplanets. We introduce relevant temperatures and timescales derived from physical principles to elucidate the mass-loss process. Our analytical mass-loss model is based on phenomenology and consistent across a range of planetary parameters. We compared our mass-loss efficiency with that of radiation hydrodynamic simulations, finding that our model can predict efficiency in both energy-limited and recombination-limited regimes. We further applied our model to exoplanets observed with hydrogen absorption (Lyα and Hα). Our findings suggest that Lyα absorption is detectable in planets subjected to intermediate EUV flux; under these conditions, the escaping outflow is insufficient in low-EUV environments, while the photoionization timescale remains short in high EUV ranges. Conversely, Hα absorption is detectable under high-EUV-flux conditions, facilitated by the intense Lyα flux exciting hydrogen atoms. According to our model, the non-detection of neutral hydrogen can be explained by a low mass-loss rate and is not necessarily due to stellar wind confinement or the absence of a hydrogen-dominated atmosphere in many cases. This model can help identify future observational targets and explicates the unusual absorption detection/non-detection patterns observed in recent studies.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"56 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143661296","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 : 2025-03-19DOI: 10.1051/0004-6361/202453545
R. Geyer, S. A. Klioner, L. Lindegren, U. Lammers
Context. A gravitational wave (GW) passing through an astrometric observer causes periodic shifts of the apparent star positions measured by the observer. For a GW of sufficient amplitude and duration, at a suitable frequency, these shifts might be detected with a Gaia-like astrometric telescope.Aims. This paper is aimed at making a detailed analysis of the effects of GWs on an astrometric solution based on Gaia-like observations, which are one-dimensional and strictly differential between two widely separated fields of view, following a prescribed scanning law.Methods. We present a simple geometric model for the astrometric effects of a plane GW in terms of the time-dependent positional shifts. Using this model, we discuss the general interaction between the GW and a Gaia-like observation. Numerous Gaia-like astrometric solutions have been computed, taking as input simulated observations that include the effects of a continuous plain GW with constant parameters and periods ranging from ~50 days to 100 years. The resulting solutions have been analysed in terms of the systematic errors on astrometric and attitude parameters, as well as the observational residuals.Results. We found that a significant part of the GW signal is absorbed by the astrometric parameters, leading to astrometric errors of a magnitude (in radians) comparable to the strain parameters. These astrometric errors are generally impossible to detect because the true (unperturbed) astrometric parameters are not known with a corresponding level of accuracy. The astrometric errors are especially large for specific GW frequencies that are linear combinations of two characteristic frequencies of the scanning law. Nevertheless, for all GW periods smaller than the time span covered by the observations, significant parts of the GW signal also go into the astrometric residuals. This fosters the hope for a GW detection algorithm based on the residuals of standard Gaia-like astrometric solutions.
{"title":"Influence of a continuous plane gravitational wave on Gaia-like astrometry","authors":"R. Geyer, S. A. Klioner, L. Lindegren, U. Lammers","doi":"10.1051/0004-6361/202453545","DOIUrl":"https://doi.org/10.1051/0004-6361/202453545","url":null,"abstract":"<i>Context.<i/> A gravitational wave (GW) passing through an astrometric observer causes periodic shifts of the apparent star positions measured by the observer. For a GW of sufficient amplitude and duration, at a suitable frequency, these shifts might be detected with a <i>Gaia<i/>-like astrometric telescope.<i>Aims.<i/> This paper is aimed at making a detailed analysis of the effects of GWs on an astrometric solution based on <i>Gaia<i/>-like observations, which are one-dimensional and strictly differential between two widely separated fields of view, following a prescribed scanning law.<i>Methods.<i/> We present a simple geometric model for the astrometric effects of a plane GW in terms of the time-dependent positional shifts. Using this model, we discuss the general interaction between the GW and a <i>Gaia<i/>-like observation. Numerous <i>Gaia<i/>-like astrometric solutions have been computed, taking as input simulated observations that include the effects of a continuous plain GW with constant parameters and periods ranging from ~50 days to 100 years. The resulting solutions have been analysed in terms of the systematic errors on astrometric and attitude parameters, as well as the observational residuals.<i>Results.<i/> We found that a significant part of the GW signal is absorbed by the astrometric parameters, leading to astrometric errors of a magnitude (in radians) comparable to the strain parameters. These astrometric errors are generally impossible to detect because the true (unperturbed) astrometric parameters are not known with a corresponding level of accuracy. The astrometric errors are especially large for specific GW frequencies that are linear combinations of two characteristic frequencies of the scanning law. Nevertheless, for all GW periods smaller than the time span covered by the observations, significant parts of the GW signal also go into the astrometric residuals. This fosters the hope for a GW detection algorithm based on the residuals of standard <i>Gaia<i/>-like astrometric solutions.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"34 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143661338","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 : 2025-03-19DOI: 10.1051/0004-6361/202453222
Marco Fenucci, Bojan Novaković, Pengfei Zhang, Albino Carbognani, Marco Micheli, Laura Faggioli, Francesco Gianotto, Francisco Ocaña, Dora Föhring, Juan Luis Cano, Luca Conversi, Richard Moissl
Context. (469219) Kamo‘oalewa is a small near-Earth asteroid (NEA) that is currently a quasi-satellite of the Earth. Light curve measurements have also revealed a rotation period of only about 30 minutes. This asteroid has been selected as the target of the Tianwen-2 sample-return mission of the China National Space Administration.Aims. The first goal of this paper is to observe and improve the orbit determination of (469219) Kamo‘oalewa, and to better determine the Yarkovsky effect acting on it. The second goal is to estimate the thermal inertia of the asteroid, using an improved Yarkovsky effect determination.Methods. Our observational campaign imaged the asteroid from the Loiano Astronomical Station and from the Calar Alto Observatory, in March 2024. We also accurately re-measured a precovery detection from the Sloan Digital Sky Survey from 2004. New astrometry was later used in a seven-dimensional (7D) orbit determination, aimed at estimating both the orbital elements and the Yarkovsky effect. The thermal inertia was later studied by using the ASTERIA, a new method suitable for estimating the thermal inertia of small asteroids.Results. We detected a semi-major axis drift of (-67.35 ± 4.70) × 10−4 au My−1 due to the Yarkovsky effect, with a high signal-tonoise ratio (S/N) of 14. The new orbit solution also significantly reduced the position uncertainty for the arrival of the Tianwen-2 spacecraft. By using different models for the physical parameters of Kamo‘oalewa, the ASTERIA model estimated the thermal inertia at Γ = 150−45+90 J m−2 K−1 s−1/2 or Γ = 181−60+95 J m−2 K−1 s−1/2.
{"title":"Astrometry, orbit determination, and thermal inertia of the Tianwen-2 target asteroid (469219) Kamo‘oalewa","authors":"Marco Fenucci, Bojan Novaković, Pengfei Zhang, Albino Carbognani, Marco Micheli, Laura Faggioli, Francesco Gianotto, Francisco Ocaña, Dora Föhring, Juan Luis Cano, Luca Conversi, Richard Moissl","doi":"10.1051/0004-6361/202453222","DOIUrl":"https://doi.org/10.1051/0004-6361/202453222","url":null,"abstract":"<i>Context.<i/> (469219) Kamo‘oalewa is a small near-Earth asteroid (NEA) that is currently a quasi-satellite of the Earth. Light curve measurements have also revealed a rotation period of only about 30 minutes. This asteroid has been selected as the target of the Tianwen-2 sample-return mission of the China National Space Administration.<i>Aims.<i/> The first goal of this paper is to observe and improve the orbit determination of (469219) Kamo‘oalewa, and to better determine the Yarkovsky effect acting on it. The second goal is to estimate the thermal inertia of the asteroid, using an improved Yarkovsky effect determination.<i>Methods.<i/> Our observational campaign imaged the asteroid from the Loiano Astronomical Station and from the Calar Alto Observatory, in March 2024. We also accurately re-measured a precovery detection from the Sloan Digital Sky Survey from 2004. New astrometry was later used in a seven-dimensional (7D) orbit determination, aimed at estimating both the orbital elements and the Yarkovsky effect. The thermal inertia was later studied by using the ASTERIA, a new method suitable for estimating the thermal inertia of small asteroids.<i>Results.<i/> We detected a semi-major axis drift of (-67.35 ± 4.70) × 10<sup><b>−<b/>4<sup/> au My<sup>−1<sup/> due to the Yarkovsky effect, with a high signal-tonoise ratio (S/N) of 14. The new orbit solution also significantly reduced the position uncertainty for the arrival of the Tianwen-2 spacecraft. By using different models for the physical parameters of Kamo‘oalewa, the ASTERIA model estimated the thermal inertia at Γ = 150<sub>−45<sub/><sup>+90<sup/> J m<sup>−2<sup/> K<sup>−1<sup/> s<sup>−1/2<sup/> or Γ = 181<sub>−60<sub/><sup>+95<sup/> J m<sup>−2<sup/> K<sup>−1<sup/> s<sup>−1/2<sup/>.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"92 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143661289","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 : 2025-03-19DOI: 10.1051/0004-6361/202453600
Marta Fatović, Dragana Ilić, Andjelka B. Kovačević, Lovro Palaversa, Saša Simić, Luka Č. Popović, Karun Thanjavur, Oleksandra Razim, Željko Ivezić, Minghao Yue, Xiaohui Fan
Context. We present results from our spectroscopic follow-up of SDSS J2320+0024, a candidate binary supermassive black hole (SMBH) with a suspected subparsec separation, identified by a 278-day periodicity observed in its multiband optical light curves. Such systems serve as a crucial link between binaries with long periods (tens of years), which are influenced by tidal forces with minimal gravitational wave damping, and ultra-short-period binaries (≤order of days), which are dominated by gravitational wave-driven inspiral.Aims. We investigated the dramatic variability in the complex Mg II emission line profile with the aim of testing the alignments of the observed photometric light curves and the spectroscopic signatures in the context of the binary SMBH system.Methods. We extracted the pure broad Mg II line from newly obtained Gemini and Magellan spectra and measured the emission line parameters to determine the fundamental dynamical parameters of the SMBH’s binary system. We adopted the PoSKI subparsec binary SMBH model, which includes a broad-line region around a less massive component and a circumbinary broad-line region, to interpret the observed variability in the spectral profile.Results. We find that the Mg II broad-line profile has a distinctive complex shape, with asymmetry and two peaks, which has varied across recent and archival observations. The temporal variability of the Mg II line profile may be associated with emission from the binary SMBH system, whose components have masses M1 = 2 × 107M⊙ and M2 = 2 × 108M⊙ and eccentricity e = 0.1. We discuss other plausible physical interpretations. With a total estimated mass of ∼109M⊙ and a sub-annual orbital period, this system may be a rare example of a high-mass compact SMBH binary candidate and, thus, should be part of further investigations of the evolution of binary systems. This study highlights the synergies between spectroscopic follow-up and future massive time-domain photometric surveys, such as the Vera C. Rubin Observatory Legacy Survey of Space and Time.
{"title":"Time evolution of Mg II in SDSS J2320+0024: Implications for a subparsec binary supermassive black hole system","authors":"Marta Fatović, Dragana Ilić, Andjelka B. Kovačević, Lovro Palaversa, Saša Simić, Luka Č. Popović, Karun Thanjavur, Oleksandra Razim, Željko Ivezić, Minghao Yue, Xiaohui Fan","doi":"10.1051/0004-6361/202453600","DOIUrl":"https://doi.org/10.1051/0004-6361/202453600","url":null,"abstract":"<i>Context.<i/> We present results from our spectroscopic follow-up of SDSS J2320+0024, a candidate binary supermassive black hole (SMBH) with a suspected subparsec separation, identified by a 278-day periodicity observed in its multiband optical light curves. Such systems serve as a crucial link between binaries with long periods (tens of years), which are influenced by tidal forces with minimal gravitational wave damping, and ultra-short-period binaries (≤order of days), which are dominated by gravitational wave-driven inspiral.<i>Aims.<i/> We investigated the dramatic variability in the complex Mg II emission line profile with the aim of testing the alignments of the observed photometric light curves and the spectroscopic signatures in the context of the binary SMBH system.<i>Methods.<i/> We extracted the pure broad Mg II line from newly obtained Gemini and Magellan spectra and measured the emission line parameters to determine the fundamental dynamical parameters of the SMBH’s binary system. We adopted the PoSKI subparsec binary SMBH model, which includes a broad-line region around a less massive component and a circumbinary broad-line region, to interpret the observed variability in the spectral profile.<i>Results.<i/> We find that the Mg II broad-line profile has a distinctive complex shape, with asymmetry and two peaks, which has varied across recent and archival observations. The temporal variability of the Mg II line profile may be associated with emission from the binary SMBH system, whose components have masses <i>M<i/><sub>1<sub/> = 2 × 10<sup>7<sup/> <i>M<i/><sub>⊙<sub/> and <i>M<i/><sub>2<sub/> = 2 × 10<sup>8<sup/> <i>M<i/><sub>⊙<sub/> and eccentricity <i>e<i/> = 0.1. We discuss other plausible physical interpretations. With a total estimated mass of ∼10<sup>9<sup/> <i>M<i/><sub>⊙<sub/> and a sub-annual orbital period, this system may be a rare example of a high-mass compact SMBH binary candidate and, thus, should be part of further investigations of the evolution of binary systems. This study highlights the synergies between spectroscopic follow-up and future massive time-domain photometric surveys, such as the <i>Vera C. Rubin<i/> Observatory Legacy Survey of Space and Time.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"61 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143661294","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 : 2025-03-19DOI: 10.1051/0004-6361/202553764
P. Koten, D. Čapek, J. Tóth, L. Shrbený, J. Borovička, J. Vaubaillon, F. Zander, D. Buttsworth, S. Loehle
Context. To date, only a few meteor clusters have been instrumentally recorded. This means that every new detection is an important contribution to the understanding of these phenomena, which are thought to be evidence of the meteoroid fragmentation in the Solar System.Aims. On May 31 2022 at 6:48:55 UT, a cluster consisting of 52 meteors was detected within 8.5 seconds during a predicted outburst of the τ-Herculid meteor shower. The aim of this paper is to reconstruct the atmospheric trajectories of the meteors and use the collected information to deduce the origin of the cluster.Methods. The meteors were recorded by two video cameras during an airborne campaign. Due to only the single station observation, their trajectories were estimated under the assumption that they belonged to the meteor shower. The mutual positions of the fragments, together with their photometric masses, were used to model the processes leading to the formation of the cluster.Results. The physical properties of the cluster meteors are very similar to the properties of the τ-Herculids. This finding confirms the assumption of the shower membership used for the computation of atmospheric trajectories. This is the third cluster that we have studied in detail, but the first one in which we do not see the mass separation of the particles. The cluster is probably less than 2.5 days old, which is too short for such a complete mass separation. Such an age would imply disintegration due to thermal stress. However, we cannot rule out an age of only a few hours, which would allow for other fragmentation mechanisms.
{"title":"A very young τ-Herculid meteor cluster observed during a 2022 shower outburst","authors":"P. Koten, D. Čapek, J. Tóth, L. Shrbený, J. Borovička, J. Vaubaillon, F. Zander, D. Buttsworth, S. Loehle","doi":"10.1051/0004-6361/202553764","DOIUrl":"https://doi.org/10.1051/0004-6361/202553764","url":null,"abstract":"<i>Context<i/>. To date, only a few meteor clusters have been instrumentally recorded. This means that every new detection is an important contribution to the understanding of these phenomena, which are thought to be evidence of the meteoroid fragmentation in the Solar System.<i>Aims<i/>. On May 31 2022 at 6:48:55 UT, a cluster consisting of 52 meteors was detected within 8.5 seconds during a predicted outburst of the <i>τ<i/>-Herculid meteor shower. The aim of this paper is to reconstruct the atmospheric trajectories of the meteors and use the collected information to deduce the origin of the cluster.<i>Methods<i/>. The meteors were recorded by two video cameras during an airborne campaign. Due to only the single station observation, their trajectories were estimated under the assumption that they belonged to the meteor shower. The mutual positions of the fragments, together with their photometric masses, were used to model the processes leading to the formation of the cluster.<i>Results<i/>. The physical properties of the cluster meteors are very similar to the properties of the <i>τ<i/>-Herculids. This finding confirms the assumption of the shower membership used for the computation of atmospheric trajectories. This is the third cluster that we have studied in detail, but the first one in which we do not see the mass separation of the particles. The cluster is probably less than 2.5 days old, which is too short for such a complete mass separation. Such an age would imply disintegration due to thermal stress. However, we cannot rule out an age of only a few hours, which would allow for other fragmentation mechanisms.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"8 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143661490","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 : 2025-03-19DOI: 10.1051/0004-6361/202453611
P. A. Palicio, A. Recio-Blanco, T. Tepper-García, E. Poggio, S. Peirani, Y. Dubois, P. J. McMillan, J. Bland-Hawthorn, K. Kraljic, M. Barbillon
Context. Spiral arms play a key role in the evolution of disc galaxies, defining their morphology, star formation, chemistry, and dynamics. Among their various implications, it has been observed in the Milky Way disc that the distribution of Gaia Data Release 3 (DR3) radial actions exhibits structures that might be related to the spiral arms.Aims. Our goal is to investigate the relationship between regions of low radial action identified in simulated discs and the location of the spiral arms, such as that suggested for the Galaxy in previous studies.Methods. For a sample of 23 simulated spiral galaxies, we modelled the axisymmetric component of their gravitational potential to compute the radial action of their stellar particles using the Stäckel fudge. The spatial distribution of the radial action was then compared to the location of the spiral arms, identified as overdensities in the stellar surface density using a kernel density estimator.Results. Our analysis reveals a strong correlation between the radial action distribution and the spiral arms in 18 of 23 simulated galaxies. However, notable discrepancies are observed in the remaining five, since they are profoundly out-of-equilibrium systems, such as galaxies influenced by external interactions or spiral arms still in the process of winding up. Additionally, spiral arms are consistently traced across young, intermediate, and old stellar populations (≥3 Gyr) in most simulations, suggesting that they are supported by stars spanning a broad age range.Conclusions. We have confirmed that, in general, there is a tendency for spatial correlation between spiral arms and stellar populations featuring low values of the radial action, as discussed in the literature using Gaia DR3 data. However, discrepancies between features in the radial action distribution and the spiral structure can be interpreted as signatures of recent disturbances, a scenario applicable to the Milky Way. Furthermore, populations at least as old as 3 Gyr trace the spiral arms with no significant misalignment across age bins, suggesting a possible theoretical interpretation of the observations obtained with Gaia data. A linear relation between the maximum value of the radial action of the spiral arms and the vertical scale-length is found, which is also satisfied by the Milky Way.
{"title":"Signatures of simulated spiral arms on radial actions","authors":"P. A. Palicio, A. Recio-Blanco, T. Tepper-García, E. Poggio, S. Peirani, Y. Dubois, P. J. McMillan, J. Bland-Hawthorn, K. Kraljic, M. Barbillon","doi":"10.1051/0004-6361/202453611","DOIUrl":"https://doi.org/10.1051/0004-6361/202453611","url":null,"abstract":"<i>Context.<i/> Spiral arms play a key role in the evolution of disc galaxies, defining their morphology, star formation, chemistry, and dynamics. Among their various implications, it has been observed in the Milky Way disc that the distribution of Gaia Data Release 3 (DR3) radial actions exhibits structures that might be related to the spiral arms.<i>Aims.<i/> Our goal is to investigate the relationship between regions of low radial action identified in simulated discs and the location of the spiral arms, such as that suggested for the Galaxy in previous studies.<i>Methods.<i/> For a sample of 23 simulated spiral galaxies, we modelled the axisymmetric component of their gravitational potential to compute the radial action of their stellar particles using the Stäckel fudge. The spatial distribution of the radial action was then compared to the location of the spiral arms, identified as overdensities in the stellar surface density using a kernel density estimator.<i>Results.<i/> Our analysis reveals a strong correlation between the radial action distribution and the spiral arms in 18 of 23 simulated galaxies. However, notable discrepancies are observed in the remaining five, since they are profoundly out-of-equilibrium systems, such as galaxies influenced by external interactions or spiral arms still in the process of winding up. Additionally, spiral arms are consistently traced across young, intermediate, and old stellar populations (≥3 Gyr) in most simulations, suggesting that they are supported by stars spanning a broad age range.<i>Conclusions.<i/> We have confirmed that, in general, there is a tendency for spatial correlation between spiral arms and stellar populations featuring low values of the radial action, as discussed in the literature using Gaia DR3 data. However, discrepancies between features in the radial action distribution and the spiral structure can be interpreted as signatures of recent disturbances, a scenario applicable to the Milky Way. Furthermore, populations at least as old as 3 Gyr trace the spiral arms with no significant misalignment across age bins, suggesting a possible theoretical interpretation of the observations obtained with Gaia data. A linear relation between the maximum value of the radial action of the spiral arms and the vertical scale-length is found, which is also satisfied by the Milky Way.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"183 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143661287","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 : 2025-03-19DOI: 10.1051/0004-6361/202453616
T. Borkovits, S. A. Rappaport, T. Mitnyan, I. B. Bíró, I. Csányi, E. Forgács-Dajka, A. Forró, T. Hajdu, B. Seli, J. Sztakovics, A. Göblyös, A. Pál
Context. A former analysis of eclipse timing variation (ETV) curves of eclipsing binaries (EBs) observed by the Kepler spacecraft during its ∼4-year-long prime mission has led to the discovery and characterization of 221 hierarchical triple star system with different confidence levels. Although the prime Kepler mission ended in 2013 (a little more than a decade ago), the TESS space telescope has revisited the original Kepler field on several occasions in between 2019 and 2024, thereby extending the time base of high-precision eclipse timing observations for a substantially longer interval.Aims. In this paper, we re-analyse the extended ETV curves of the formerly identified triple star candidates and many other Kepler EBs. Besides the confirmations of the former findings and/or the improvements of the triple systems’ orbital properties, the extended time base allows us to identify several new, longer outer period triple systems, and it also makes a more detailed study of the dynamical perturbations in the tightest triple stars possible.Methods. We extend the ETV curves of the Kepler triples with those mid-eclipse times that can be deduced from the TESS observations and, moreover, from targeted ground-based follow-up observations for a number of the objects. In general, we used the same methods that were applied for the older studies, which are described in the literature. Due to the lower quality of the TESS observations, however, for the fainter systems we averaged light curves of the EBs for 5–20 consecutive cycles, and thereby calculated ‘normal’ minima from these averaged light curves.Results. In conclusion, we identified 243 hierarchical triple star candidates in the Kepler sample. This sample strongly overlaps our former, nine-year-old sample, confirming the older results, or providing new solutions for 193 systems of the 2016 sample. For the remaining 28 hierarchical triple candidates of that former study, we have been unable to find new solutions, either because of the disappearance of the eclipses due to orbital plane precession, or due to instrumental reasons. On the other hand, due to the extended time series, we have been able to identify 50 new, longer-period triple star candidates as well. We briefly discuss the main properties of each individual system and present statistical studies of the results.
{"title":"Then and now: A new look at the eclipse timing variations of hierarchical triple star candidates in the primordial Kepler field, revisited by TESS","authors":"T. Borkovits, S. A. Rappaport, T. Mitnyan, I. B. Bíró, I. Csányi, E. Forgács-Dajka, A. Forró, T. Hajdu, B. Seli, J. Sztakovics, A. Göblyös, A. Pál","doi":"10.1051/0004-6361/202453616","DOIUrl":"https://doi.org/10.1051/0004-6361/202453616","url":null,"abstract":"<i>Context.<i/> A former analysis of eclipse timing variation (ETV) curves of eclipsing binaries (EBs) observed by the <i>Kepler<i/> spacecraft during its ∼4-year-long prime mission has led to the discovery and characterization of 221 hierarchical triple star system with different confidence levels. Although the prime <i>Kepler<i/> mission ended in 2013 (a little more than a decade ago), the TESS space telescope has revisited the original <i>Kepler<i/> field on several occasions in between 2019 and 2024, thereby extending the time base of high-precision eclipse timing observations for a substantially longer interval.<i>Aims.<i/> In this paper, we re-analyse the extended ETV curves of the formerly identified triple star candidates and many other <i>Kepler<i/> EBs. Besides the confirmations of the former findings and/or the improvements of the triple systems’ orbital properties, the extended time base allows us to identify several new, longer outer period triple systems, and it also makes a more detailed study of the dynamical perturbations in the tightest triple stars possible.<i>Methods.<i/> We extend the ETV curves of the <i>Kepler<i/> triples with those mid-eclipse times that can be deduced from the TESS observations and, moreover, from targeted ground-based follow-up observations for a number of the objects. In general, we used the same methods that were applied for the older studies, which are described in the literature. Due to the lower quality of the TESS observations, however, for the fainter systems we averaged light curves of the EBs for 5–20 consecutive cycles, and thereby calculated ‘normal’ minima from these averaged light curves.<i>Results.<i/> In conclusion, we identified 243 hierarchical triple star candidates in the <i>Kepler<i/> sample. This sample strongly overlaps our former, nine-year-old sample, confirming the older results, or providing new solutions for 193 systems of the 2016 sample. For the remaining 28 hierarchical triple candidates of that former study, we have been unable to find new solutions, either because of the disappearance of the eclipses due to orbital plane precession, or due to instrumental reasons. On the other hand, due to the extended time series, we have been able to identify 50 new, longer-period triple star candidates as well. We briefly discuss the main properties of each individual system and present statistical studies of the results.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"26 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143661295","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 : 2025-03-19DOI: 10.1051/0004-6361/202453271
Matthew J. Green, Yoav Ziv, Hans-Walter Rix, Dan Maoz, Ikram Hamoudy, Tsevi Mazeh, Simchon Faigler, Marco C. Lam, Kareem El-Badry, George Hume, James Munday, Paige Yarker
Stellar-mass black holes descend from high-mass stars, most of which had stellar binary companions. However, the number of those binary systems that survive the binary evolution and black hole formation is uncertain by multiple orders of magnitude. The survival rate is particularly uncertain for massive stars with low-mass companions, which are thought to be the progenitors of most black hole X-ray binaries. We present a search for close black hole companions (orbital period ≲3 days, equivalent to separation ≲20 R⊙) to AFGK-type stars in TESS; that is, the non-accreting counterparts to and progenitors of low-mass X-ray binaries. Such black holes can be detected by the tidally induced ellipsoidal deformation of the visible star, and the ensuing photometric light curve variations. From an initial sample of 4.7 × 106TESS stars, we have selected 457 candidate ellipsoidal variables with large mass ratios. However, after spectroscopic follow-up of 250 of them, none so far are consistent with a close black hole companion. On the basis of this non-detection, we determine (with 2σ confidence) that fewer than one in 105 solar-type stars in the solar neighbourhood hosts a short-period black hole companion. This upper limit is in tension with a number of ‘optimistic’ population models in the literature that predict short-period black hole companions around one in ∼104 − 5 stars. Our limit is still consistent with other models that predict only a few in ∼107 − 8.
{"title":"An upper limit on the frequency of short-period black hole companions to Sun-like stars","authors":"Matthew J. Green, Yoav Ziv, Hans-Walter Rix, Dan Maoz, Ikram Hamoudy, Tsevi Mazeh, Simchon Faigler, Marco C. Lam, Kareem El-Badry, George Hume, James Munday, Paige Yarker","doi":"10.1051/0004-6361/202453271","DOIUrl":"https://doi.org/10.1051/0004-6361/202453271","url":null,"abstract":"Stellar-mass black holes descend from high-mass stars, most of which had stellar binary companions. However, the number of those binary systems that survive the binary evolution and black hole formation is uncertain by multiple orders of magnitude. The survival rate is particularly uncertain for massive stars with low-mass companions, which are thought to be the progenitors of most black hole X-ray binaries. We present a search for close black hole companions (orbital period ≲3 days, equivalent to separation ≲20 <i>R<i/><sub>⊙<sub/>) to AFGK-type stars in <i>TESS<i/>; that is, the non-accreting counterparts to and progenitors of low-mass X-ray binaries. Such black holes can be detected by the tidally induced ellipsoidal deformation of the visible star, and the ensuing photometric light curve variations. From an initial sample of 4.7 × 10<sup>6<sup/><i>TESS<i/> stars, we have selected 457 candidate ellipsoidal variables with large mass ratios. However, after spectroscopic follow-up of 250 of them, none so far are consistent with a close black hole companion. On the basis of this non-detection, we determine (with 2<i>σ<i/> confidence) that fewer than one in 10<sup>5<sup/> solar-type stars in the solar neighbourhood hosts a short-period black hole companion. This upper limit is in tension with a number of ‘optimistic’ population models in the literature that predict short-period black hole companions around one in ∼10<sup>4 − 5<sup/> stars. Our limit is still consistent with other models that predict only a few in ∼10<sup>7 − 8<sup/>.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"70 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143661288","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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