S. Chastain, A. J. van der Horst, A. Rowlinson, L. Rhodes, A. Andersson, R. Diretse, R. Fender, P. Woudt
A new generation of radio telescopes with excellent sensitivity, instantaneous uv coverage, and large fields of view, are providing unprecedented opportunities for performing commensal transient searches. Here we present such a commensal search in deep observations of short gamma-ray burst fields carried out with the MeerKAT radio telescope in South Africa at 1.3 GHz. These four hour observations of eight different fields span survey lengths of weeks to months. We also carry out transient searches in time slices of the full observations, at timescales of 15 minutes, and 8 seconds. We find 122 variable sources on the long timescales, of which 52 are likely active galactic nuclei, but there are likely also some radio flaring stars. While the variability is intrinsic in at least two cases, most of it is consistent with interstellar scintillation. In this study, we also place constraints on transient rates based on state-of-the-art transient simulations codes. We place an upper limit of 2 × 10−4 transients per day per square degree for transients with peak flux of 5 mJy, and an upper limit of 2.5 × 10−2 transients per day per square degree for transients with a fluence of 10 Jy ms, the minimum detectable fluence of our survey.
{"title":"Commensal Transient Searches in Eight Short Gamma Ray Burst Fields","authors":"S. Chastain, A. J. van der Horst, A. Rowlinson, L. Rhodes, A. Andersson, R. Diretse, R. Fender, P. Woudt","doi":"10.1093/mnras/stad2714","DOIUrl":"https://doi.org/10.1093/mnras/stad2714","url":null,"abstract":"\u0000 A new generation of radio telescopes with excellent sensitivity, instantaneous uv coverage, and large fields of view, are providing unprecedented opportunities for performing commensal transient searches. Here we present such a commensal search in deep observations of short gamma-ray burst fields carried out with the MeerKAT radio telescope in South Africa at 1.3 GHz. These four hour observations of eight different fields span survey lengths of weeks to months. We also carry out transient searches in time slices of the full observations, at timescales of 15 minutes, and 8 seconds. We find 122 variable sources on the long timescales, of which 52 are likely active galactic nuclei, but there are likely also some radio flaring stars. While the variability is intrinsic in at least two cases, most of it is consistent with interstellar scintillation. In this study, we also place constraints on transient rates based on state-of-the-art transient simulations codes. We place an upper limit of 2 × 10−4 transients per day per square degree for transients with peak flux of 5 mJy, and an upper limit of 2.5 × 10−2 transients per day per square degree for transients with a fluence of 10 Jy ms, the minimum detectable fluence of our survey.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":" ","pages":""},"PeriodicalIF":4.8,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47183109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
K. Ertini, G. Folatelli, L. Martinez, M. Bersten, J. Anderson, C. Ashall, E. Baron, S. Bose, P. J. Brown, C. Burns, J. M. DerKacy, L. Ferrari, L. Galbany, E. Hsiao, S. Kumar, J. Lu, P. Mazzali, N. Morrell, M. Orellana, P. Pessi, M. Phillips, A. Piro, A. Polin, M. Shahbandeh, B. Shappee, M. Stritzinger, N. Suntzeff, M. Tucker, N. Elias-Rosa, H. Kuncarayakti, C. Gutiérrez, A. Kozyreva, T. Müller-Bravo, T.-W. Chen, J. Hinkle, A. Payne, P. Székely, T. Szalai, B. Barna, R. Könyves-Tóth, D. Bánhidi, I. B. Bíró, I. Csányi, L. Kriskovits, A. Pál, Z. Szabó, R. Szakáts, K. Vida, J. Vinkó, M. Gromadzki, L. Harvey, M. Nicholl, E. Paraskeva, D. Young, B. Englert
We present extensive ultraviolet (UV) and optical photometric and optical spectroscopic follow-up of supernova (SN) 2021gno by the ”Precision Observations of Infant Supernova Explosions” (POISE) project, starting less than two days after the explosion. Given its intermediate luminosity, fast photometric evolution, and quick transition to the nebular phase with spectra dominated by [Ca II] lines, SN 2021gno belongs to the small family of Calcium-rich transients. Moreover, it shows double-peaked light curves, a phenomenon shared with only four other Calcium-rich events. The projected distance from the center of the host galaxy is not as large as other objects in this family. The initial optical light-curve peaks coincide with a very quick decline of the UV flux, indicating a fast initial cooling phase. Through hydrodynamical modelling of the bolometric light curve and line velocity evolution, we found that the observations are compatible with the explosion of a highly-stripped massive star with an ejecta mass of 0.8 M⊙ and a 56Ni mass of 0.024 M⊙. The initial cooling phase (first light curve peak) is explained by the presence of an extended circumstellar material comprising ∼10−2 M⊙ with an extension of 1100 R⊙. We discuss if hydrogen features are present in both maximum-light and nebular spectra, and its implications in terms of the proposed progenitor scenarios for Calcium-rich transients.
{"title":"SN 2021gno: a Calcium-rich transient with double-peaked light curves","authors":"K. Ertini, G. Folatelli, L. Martinez, M. Bersten, J. Anderson, C. Ashall, E. Baron, S. Bose, P. J. Brown, C. Burns, J. M. DerKacy, L. Ferrari, L. Galbany, E. Hsiao, S. Kumar, J. Lu, P. Mazzali, N. Morrell, M. Orellana, P. Pessi, M. Phillips, A. Piro, A. Polin, M. Shahbandeh, B. Shappee, M. Stritzinger, N. Suntzeff, M. Tucker, N. Elias-Rosa, H. Kuncarayakti, C. Gutiérrez, A. Kozyreva, T. Müller-Bravo, T.-W. Chen, J. Hinkle, A. Payne, P. Székely, T. Szalai, B. Barna, R. Könyves-Tóth, D. Bánhidi, I. B. Bíró, I. Csányi, L. Kriskovits, A. Pál, Z. Szabó, R. Szakáts, K. Vida, J. Vinkó, M. Gromadzki, L. Harvey, M. Nicholl, E. Paraskeva, D. Young, B. Englert","doi":"10.1093/mnras/stad2705","DOIUrl":"https://doi.org/10.1093/mnras/stad2705","url":null,"abstract":"\u0000 We present extensive ultraviolet (UV) and optical photometric and optical spectroscopic follow-up of supernova (SN) 2021gno by the ”Precision Observations of Infant Supernova Explosions” (POISE) project, starting less than two days after the explosion. Given its intermediate luminosity, fast photometric evolution, and quick transition to the nebular phase with spectra dominated by [Ca II] lines, SN 2021gno belongs to the small family of Calcium-rich transients. Moreover, it shows double-peaked light curves, a phenomenon shared with only four other Calcium-rich events. The projected distance from the center of the host galaxy is not as large as other objects in this family. The initial optical light-curve peaks coincide with a very quick decline of the UV flux, indicating a fast initial cooling phase. Through hydrodynamical modelling of the bolometric light curve and line velocity evolution, we found that the observations are compatible with the explosion of a highly-stripped massive star with an ejecta mass of 0.8 M⊙ and a 56Ni mass of 0.024 M⊙. The initial cooling phase (first light curve peak) is explained by the presence of an extended circumstellar material comprising ∼10−2 M⊙ with an extension of 1100 R⊙. We discuss if hydrogen features are present in both maximum-light and nebular spectra, and its implications in terms of the proposed progenitor scenarios for Calcium-rich transients.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":" ","pages":""},"PeriodicalIF":4.8,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45950004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
In this paper we develop a framework for studying unstratified, magnetised eccentric discs and compute uniformly precessing eccentric modes in a cylindrical annulus which provide convenient initial conditions for numerical simulations. The presence of a magnetic field in an eccentric disc can be described by an effective gas with a modified equation of state. At magnetic field strengths relevant to the magneto-rotational instability the magnetic field has negligible influence on the evolution of the eccentric disc, however the eccentric disc can significantly enhance the magnetic field strength over that in the a circular disc. We verify the suitability of these eccentric disc solutions by carrying out 2D simulations in RAMSES. Our simulated modes (in 2D) follow a similar evolution to the purely hydrodynamical modes, matching theoretical expectations, provided they are adequately resolved. Such solutions will provide equilibrium states for studies of the eccentric magneto-rotational instability and magnetised parametric instability in unstratified discs and are useful for exploring the response of disc turbulence on top of a fluid flow varying on the orbital timescale.
{"title":"Linear and nonlinear eccentric mode evolution in unstratified MHD discs","authors":"Elliot M. Lynch, Janosz W. Dewberry","doi":"10.1093/mnras/stad2678","DOIUrl":"https://doi.org/10.1093/mnras/stad2678","url":null,"abstract":"\u0000 In this paper we develop a framework for studying unstratified, magnetised eccentric discs and compute uniformly precessing eccentric modes in a cylindrical annulus which provide convenient initial conditions for numerical simulations. The presence of a magnetic field in an eccentric disc can be described by an effective gas with a modified equation of state. At magnetic field strengths relevant to the magneto-rotational instability the magnetic field has negligible influence on the evolution of the eccentric disc, however the eccentric disc can significantly enhance the magnetic field strength over that in the a circular disc. We verify the suitability of these eccentric disc solutions by carrying out 2D simulations in RAMSES. Our simulated modes (in 2D) follow a similar evolution to the purely hydrodynamical modes, matching theoretical expectations, provided they are adequately resolved. Such solutions will provide equilibrium states for studies of the eccentric magneto-rotational instability and magnetised parametric instability in unstratified discs and are useful for exploring the response of disc turbulence on top of a fluid flow varying on the orbital timescale.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":" ","pages":""},"PeriodicalIF":4.8,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43477081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Chenyu He, Chengyuan Li, Weijia Sun, R. de Grijs, Lu Li, Jing Zhong, Songmei Qin, Li Chen, Li Wang, Baitian Tang, Zhengyi Shao, Cheng Xu
The split main sequences found in the colour–magnitude diagrams of star clusters younger than ∼600Myr are suggested to be caused by the dichotomy of stellar rotation rates of upper main-sequence stars. Tidal interactions have been suggested as a possible explanation of the dichotomy of the stellar rotation rates. This hypothesis proposes that the slow rotation rates of stars along the split main sequences are caused by tidal interactions in binaries. To test this scenario, we measured the variations in the radial velocities of slowly rotating stars along the split main sequence of the young Galactic cluster NGC 2422 (∼90Myr) using spectra obtained at multiple epochs with the Canada–France–Hawai’i Telescope. Our results show that most slowly rotating stars are not radial-velocity variables. Using the theory of dynamical tides, we find that the binary separations necessary to fully or partially synchronise our spectroscopic targets, on time-scales shorter than the cluster age, predict much larger radial velocity variations across multiple-epoch observations, or a much larger radial velocity dispersion at a single epoch, than the observed values. This indicates that tidal interactions are not the dominant mechanism to form slowly rotating stars along the split main sequences. As the observations of the rotation velocity distribution among B- and A-type stars in binaries of larger separations hint at a much stronger effect of braking with age, we discuss the consequences of relaxing the constraints of the dynamical tides theory.
{"title":"The role of tidal interactions in the formation of slowly rotating early-type stars in young star clusters","authors":"Chenyu He, Chengyuan Li, Weijia Sun, R. de Grijs, Lu Li, Jing Zhong, Songmei Qin, Li Chen, Li Wang, Baitian Tang, Zhengyi Shao, Cheng Xu","doi":"10.1093/mnras/stad2674","DOIUrl":"https://doi.org/10.1093/mnras/stad2674","url":null,"abstract":"\u0000 The split main sequences found in the colour–magnitude diagrams of star clusters younger than ∼600Myr are suggested to be caused by the dichotomy of stellar rotation rates of upper main-sequence stars. Tidal interactions have been suggested as a possible explanation of the dichotomy of the stellar rotation rates. This hypothesis proposes that the slow rotation rates of stars along the split main sequences are caused by tidal interactions in binaries. To test this scenario, we measured the variations in the radial velocities of slowly rotating stars along the split main sequence of the young Galactic cluster NGC 2422 (∼90Myr) using spectra obtained at multiple epochs with the Canada–France–Hawai’i Telescope. Our results show that most slowly rotating stars are not radial-velocity variables. Using the theory of dynamical tides, we find that the binary separations necessary to fully or partially synchronise our spectroscopic targets, on time-scales shorter than the cluster age, predict much larger radial velocity variations across multiple-epoch observations, or a much larger radial velocity dispersion at a single epoch, than the observed values. This indicates that tidal interactions are not the dominant mechanism to form slowly rotating stars along the split main sequences. As the observations of the rotation velocity distribution among B- and A-type stars in binaries of larger separations hint at a much stronger effect of braking with age, we discuss the consequences of relaxing the constraints of the dynamical tides theory.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":" ","pages":""},"PeriodicalIF":4.8,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41455297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
J. Thain'a-Batista, R. C. Fernandes, F. Herpich, C. M. de Oliveira, A. Werle, L. Espinosa, A. Lopes, A. V. S. Castelli, L. Sodr'e, E. Telles, A. Kanaan, T. Ribeiro, W. Schoenell
We present tests of a new method to simultaneously estimate stellar population and emission line (EL) properties of galaxies out of S-PLUS photometry. The technique uses the a l starcode, updated with an empirical prior which greatly improves its ability to estimate ELs using only the survey’s 12 bands. The tests compare the output of (noise-perturbed) synthetic photometry of SDSS galaxies to properties derived from previous full spectral fitting and detailed EL analysis. For realistic signal-to-noise ratios, stellar population properties are recovered to better than 0.2 dex in masses, mean ages, metallicities and ±0.2 mag for the extinction. More importantly, ELs are recovered remarkably well for a photometric survey. We obtain input − output dispersions of 0.05–0.2 dex for the equivalent widths of [O ii], [O iii], Hβ, Hα, [N ii], and [S ii], and even better for lines stronger than ∼5 Å. These excellent results are achieved by combining two empirical facts into a prior which restricts the EL space available for the fits: (1) Because, for the redshifts explored here, Hα and [N ii] fall in a single narrow band (J0660), their combined equivalent width is always well recovered, even when [N ii]/Hα is not. (2) We know from SDSS that $W_{mathrm{H}alpha +[rm{N}, small {II}] }$ correlates with [N ii]/Hα, which can be used to tell if a galaxy belongs to the left or right wings in the classical BPT diagnostic diagram. Example applications to integrated light and spatially resolved data are also presented, including a comparison with independent results obtained with MUSE-based integral field spectroscopy.
{"title":"Estimating stellar population and emission line properties in S-PLUS galaxies","authors":"J. Thain'a-Batista, R. C. Fernandes, F. Herpich, C. M. de Oliveira, A. Werle, L. Espinosa, A. Lopes, A. V. S. Castelli, L. Sodr'e, E. Telles, A. Kanaan, T. Ribeiro, W. Schoenell","doi":"10.1093/mnras/stad2698","DOIUrl":"https://doi.org/10.1093/mnras/stad2698","url":null,"abstract":"\u0000 We present tests of a new method to simultaneously estimate stellar population and emission line (EL) properties of galaxies out of S-PLUS photometry. The technique uses the a l starcode, updated with an empirical prior which greatly improves its ability to estimate ELs using only the survey’s 12 bands. The tests compare the output of (noise-perturbed) synthetic photometry of SDSS galaxies to properties derived from previous full spectral fitting and detailed EL analysis. For realistic signal-to-noise ratios, stellar population properties are recovered to better than 0.2 dex in masses, mean ages, metallicities and ±0.2 mag for the extinction. More importantly, ELs are recovered remarkably well for a photometric survey. We obtain input − output dispersions of 0.05–0.2 dex for the equivalent widths of [O ii], [O iii], Hβ, Hα, [N ii], and [S ii], and even better for lines stronger than ∼5 Å. These excellent results are achieved by combining two empirical facts into a prior which restricts the EL space available for the fits: (1) Because, for the redshifts explored here, Hα and [N ii] fall in a single narrow band (J0660), their combined equivalent width is always well recovered, even when [N ii]/Hα is not. (2) We know from SDSS that $W_{mathrm{H}alpha +[rm{N}, small {II}] }$ correlates with [N ii]/Hα, which can be used to tell if a galaxy belongs to the left or right wings in the classical BPT diagnostic diagram. Example applications to integrated light and spatially resolved data are also presented, including a comparison with independent results obtained with MUSE-based integral field spectroscopy.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":" ","pages":""},"PeriodicalIF":4.8,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41568162","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Panchromatic analysis of galaxy spectral energy distributions, spanning from the ultraviolet to the far-infrared, probes not only the stellar population but also the properties of interstellar dust through its extinction and long-wavelength reemission. However little work has exploited the full power of such fitting to constrain the redshift evolution of dust temperature in galaxies. To do so, we simultaneously fit ultraviolet, optical and infrared observations of stacked galaxy subsamples at a range of stellar masses and photometric redshifts at 0 < z < 5, using an energy-balance formalism. However, we find UV-emission beyond the Lyman limit in some photometric redshift selected galaxy subsamples, giving rise to the possibility of contaminated observations. We carefully define a robust, clean subsample which extends to no further than z ∼ 2. This has consistently lower derived temperatures by $4.0^{+5.0}_{-1.9}$ K, relative to the full sample. We find a linear increase in dust temperature with redshift, with Td(z) = (4.8 ± 1.5) × z + (26.2 ± 1.5) K. Our inferred temperature evolution is consistent with a modest rise in dust temperature with redshift, but inconsistent with some previous analyses. We also find a majority of photometrically-selected subsamples at z > 4.5 under-predict the IR emission while giving reasonable fits to the UV-optical. This could be due to a spatial disconnect in the locations of the UV and IR emission peaks, suggesting that an energy-balance formalism may not always be applicable in the distant Universe.
从紫外到远红外的星系光谱能量分布的全色分析，不仅可以探测恒星种群，还可以通过星际尘埃的消光和长波再发射来探测星际尘埃的特性。然而，利用这种拟合的全部力量来限制星系中尘埃温度的红移演化的工作很少。为了做到这一点，我们同时使用能量平衡形式，在恒星质量和0 < z < 5的光度红移范围内，对堆叠星系亚样本进行紫外、光学和红外观测。然而，我们发现在一些光度红移选择的星系亚样本中，紫外线辐射超过了莱曼极限，从而产生了污染观测的可能性。我们仔细定义了一个健壮、干净的子样本，其延伸范围不超过z ~ 2。相对于整个样本，这使得导出的温度始终降低了$4.0^{+5.0}_{-1.9}$ K。我们发现尘埃温度随红移呈线性增加，Td(z) =(4.8±1.5)× z +(26.2±1.5)K。我们推断的温度演变与尘埃温度随着红移的适度上升是一致的，但与之前的一些分析不一致。我们还发现大多数在z > 4.5的光度选择的子样品在给出合理的紫外光学拟合的同时低估了红外发射。这可能是由于紫外线和红外线发射峰位置的空间脱节，这表明能量平衡的形式可能并不总是适用于遥远的宇宙。
{"title":"Exploring the Evolution of Dust Temperature using Spectral Energy Distribution Fitting in a Large Photometric Survey","authors":"Gareth T Jones, E. Stanway","doi":"10.1093/mnras/stad2683","DOIUrl":"https://doi.org/10.1093/mnras/stad2683","url":null,"abstract":"\u0000 Panchromatic analysis of galaxy spectral energy distributions, spanning from the ultraviolet to the far-infrared, probes not only the stellar population but also the properties of interstellar dust through its extinction and long-wavelength reemission. However little work has exploited the full power of such fitting to constrain the redshift evolution of dust temperature in galaxies. To do so, we simultaneously fit ultraviolet, optical and infrared observations of stacked galaxy subsamples at a range of stellar masses and photometric redshifts at 0 < z < 5, using an energy-balance formalism. However, we find UV-emission beyond the Lyman limit in some photometric redshift selected galaxy subsamples, giving rise to the possibility of contaminated observations. We carefully define a robust, clean subsample which extends to no further than z ∼ 2. This has consistently lower derived temperatures by $4.0^{+5.0}_{-1.9}$ K, relative to the full sample. We find a linear increase in dust temperature with redshift, with Td(z) = (4.8 ± 1.5) × z + (26.2 ± 1.5) K. Our inferred temperature evolution is consistent with a modest rise in dust temperature with redshift, but inconsistent with some previous analyses. We also find a majority of photometrically-selected subsamples at z > 4.5 under-predict the IR emission while giving reasonable fits to the UV-optical. This could be due to a spatial disconnect in the locations of the UV and IR emission peaks, suggesting that an energy-balance formalism may not always be applicable in the distant Universe.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":" ","pages":""},"PeriodicalIF":4.8,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45972444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Regarding the recent debate about the potential circumbinary exoplanets around NY Virginis, we analyzed mid-eclipse timings of NY Vir using archival photometric data as well as our own observations and the ones from TESS. For this purpose, we first modelled the available eclipse light curves of the binary system to determine the masses of the stars. Then, we measured mid-eclipse timings by fitting the light curve model cycle-to-cycle to the light curves from TESS and our observations. By fitting a Newtonian eclipse timing model to the data, which takes both the light-time effect and potential mutual gravitational interactions into account, we derived orbital parameters and masses of the potential circumbinary planets assuming both eccentric and circular orbits. The models without a quadratic term that can model any possible secular trend, converged to comparable results. Dynamical stability tests show that our Newtonian timing solution corresponds to stable orbital configurations for two circumbinary planets with masses ∼2.3 MJup and ∼4.0 MJup in orbits with very low eccentricity. Our analyses show that the addition of quadratic term for modelling the ETV may induce the planetary orbits to be eccentric, hence more likely to be unstable. According to our findings, an upward trend in the eclipse timings followed by a downward one within the next five years is expected due to binary motion induced by circumbinary planets.
{"title":"Testing the planetary hypothesis of NY Virginis: Anticipated change in the eclipse timing trend within the next five years","authors":"E. M. Esmer, Ö. Baştürk, S. Selam","doi":"10.1093/mnras/stad2648","DOIUrl":"https://doi.org/10.1093/mnras/stad2648","url":null,"abstract":"\u0000 Regarding the recent debate about the potential circumbinary exoplanets around NY Virginis, we analyzed mid-eclipse timings of NY Vir using archival photometric data as well as our own observations and the ones from TESS. For this purpose, we first modelled the available eclipse light curves of the binary system to determine the masses of the stars. Then, we measured mid-eclipse timings by fitting the light curve model cycle-to-cycle to the light curves from TESS and our observations. By fitting a Newtonian eclipse timing model to the data, which takes both the light-time effect and potential mutual gravitational interactions into account, we derived orbital parameters and masses of the potential circumbinary planets assuming both eccentric and circular orbits. The models without a quadratic term that can model any possible secular trend, converged to comparable results. Dynamical stability tests show that our Newtonian timing solution corresponds to stable orbital configurations for two circumbinary planets with masses ∼2.3 MJup and ∼4.0 MJup in orbits with very low eccentricity. Our analyses show that the addition of quadratic term for modelling the ETV may induce the planetary orbits to be eccentric, hence more likely to be unstable. According to our findings, an upward trend in the eclipse timings followed by a downward one within the next five years is expected due to binary motion induced by circumbinary planets.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":" ","pages":""},"PeriodicalIF":4.8,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45123155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
D.A. Zakharova, I. Tikhonenko, N. Sotnikova, Anton A. Smirnov
A significant part of barred disc galaxies exhibits boxy/peanut-shaped structures (B/PS bulges) at high inclinations. Another structure also associated with the bar is a barlens, often observed in galaxies in a position close to face-on. At this viewing angle, special kinematic tests are required to detect a 3D extension of the bars in the vertical direction (B/PS bulges). We use four pure N-body models of galaxies with B/PS bulges, which have different bar morphology from bars with barlenses to the so-called face-on peanut bars. We analyse the kinematics of our models to establish how the structural features of B/PS bulges manifest themselves in the kinematics for galaxies at intermediate inclinations and whether these features are related to the barlenses. We apply the dissection of the bar into different orbital groups to determine which of them are responsible for the features of the LOSVD (line-of-sight velocity distribution), i.e., for the deep minima of the h4 parameter along the major axis of the bar. As a result, we claim that for our models at the face-on position, the kinematic signatures of a ‘peanut’ indeed track the vertical density distribution features. We conclude that orbits responsible for such kinematic signatures differ from model to model. We pay special attention to the barlens model. We show that orbits assembled into barlens are not responsible for the kinematic signatures of B/PS bulges. The results presented in this work are applicable to the interpretation of IFU observations of real galaxies.
{"title":"B/PS bulges and barlenses from a kinematic viewpoint. I","authors":"D.A. Zakharova, I. Tikhonenko, N. Sotnikova, Anton A. Smirnov","doi":"10.1093/mnras/stad2662","DOIUrl":"https://doi.org/10.1093/mnras/stad2662","url":null,"abstract":"\u0000 A significant part of barred disc galaxies exhibits boxy/peanut-shaped structures (B/PS bulges) at high inclinations. Another structure also associated with the bar is a barlens, often observed in galaxies in a position close to face-on. At this viewing angle, special kinematic tests are required to detect a 3D extension of the bars in the vertical direction (B/PS bulges). We use four pure N-body models of galaxies with B/PS bulges, which have different bar morphology from bars with barlenses to the so-called face-on peanut bars. We analyse the kinematics of our models to establish how the structural features of B/PS bulges manifest themselves in the kinematics for galaxies at intermediate inclinations and whether these features are related to the barlenses. We apply the dissection of the bar into different orbital groups to determine which of them are responsible for the features of the LOSVD (line-of-sight velocity distribution), i.e., for the deep minima of the h4 parameter along the major axis of the bar. As a result, we claim that for our models at the face-on position, the kinematic signatures of a ‘peanut’ indeed track the vertical density distribution features. We conclude that orbits responsible for such kinematic signatures differ from model to model. We pay special attention to the barlens model. We show that orbits assembled into barlens are not responsible for the kinematic signatures of B/PS bulges. The results presented in this work are applicable to the interpretation of IFU observations of real galaxies.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":" ","pages":""},"PeriodicalIF":4.8,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49357241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
A. Rubio, A. Carciofi, P. Ticiani, B. C. Mota, R. G. Vieira, D. Faes, M. Genaro, T. H. de Amorim, R. Klement, I. Araya, C. Arcos, M. Curé, A. D. de Souza, C. Georgy, C. E. Jones, M. Suffak, A. C. F. Silva
Classical Be stars are fast rotating, near main sequence B-type stars. The rotation and the presence of circumstellar discs profoundly modify the observables of active Be stars. Our goal is to infer stellar and disc parameters, as well as distance and interstellar extinction, using the currently most favoured physical models for these objects. We present BeAtlas, a grid of 61 600 NLTE radiative transfer models for Be stars, calculated with the hdust code. The grid was coupled with a Monte Carlo Markov chain code to sample the posterior distribution. We test our method on two well-studied Be stars, α Eri and β CMi, using photometric, polarimetric and spectroscopic data as input to the code. We recover literature determinations for most of the parameters of the targets, in particular the mass and age of α Eri, the disc parameters of β CMi, and their distances and inclinations. The main discrepancy is that we estimate lower rotational rates than previous works. We confirm previously detected signs of disc truncation in β CMi and note that its inner disc seems to have a flatter density slope than its outer disc. The correlations between the parameters are complex, further indicating that exploring the entire parameter space simultaneously is a more robust approach, statistically. The combination of BeAtlas and Bayesian-MCMC techniques proves successful, and a powerful new tool for the field: the fundamental parameters of any Be star can now be estimated in a matter of hours or days.
{"title":"Bayesian sampling with BeAtlas, a grid of synthetic Be star spectra I. Recovering the fundamental parameters of α Eri and β CMi","authors":"A. Rubio, A. Carciofi, P. Ticiani, B. C. Mota, R. G. Vieira, D. Faes, M. Genaro, T. H. de Amorim, R. Klement, I. Araya, C. Arcos, M. Curé, A. D. de Souza, C. Georgy, C. E. Jones, M. Suffak, A. C. F. Silva","doi":"10.1093/mnras/stad2652","DOIUrl":"https://doi.org/10.1093/mnras/stad2652","url":null,"abstract":"\u0000 Classical Be stars are fast rotating, near main sequence B-type stars. The rotation and the presence of circumstellar discs profoundly modify the observables of active Be stars. Our goal is to infer stellar and disc parameters, as well as distance and interstellar extinction, using the currently most favoured physical models for these objects. We present BeAtlas, a grid of 61 600 NLTE radiative transfer models for Be stars, calculated with the hdust code. The grid was coupled with a Monte Carlo Markov chain code to sample the posterior distribution. We test our method on two well-studied Be stars, α Eri and β CMi, using photometric, polarimetric and spectroscopic data as input to the code. We recover literature determinations for most of the parameters of the targets, in particular the mass and age of α Eri, the disc parameters of β CMi, and their distances and inclinations. The main discrepancy is that we estimate lower rotational rates than previous works. We confirm previously detected signs of disc truncation in β CMi and note that its inner disc seems to have a flatter density slope than its outer disc. The correlations between the parameters are complex, further indicating that exploring the entire parameter space simultaneously is a more robust approach, statistically. The combination of BeAtlas and Bayesian-MCMC techniques proves successful, and a powerful new tool for the field: the fundamental parameters of any Be star can now be estimated in a matter of hours or days.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":" ","pages":""},"PeriodicalIF":4.8,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45047447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
G. M. Williams, C. Cyganowski, C. Brogan, Todd R. Hunter, Pooneh Nazari, Rowan J. Smith
We present a study of the physical and chemical properties of the Extended Green Object (EGO) G19.01−0.03 using sub-arcsecond angular resolution Atacama Large Millimeter/submillimeter Array (ALMA) 1.05 mm and Karl G. Jansky Very Large Array (VLA) 1.21 cm data. G19.01−0.03 MM1, the millimetre source associated with the central massive young stellar object (MYSO), appeared isolated and potentially chemically young in previous Submillimeter Array observations. In our ∼0.4″-resolution ALMA data, MM1 has four low-mass millimetre companions within 0.12 pc, all lacking maser or outflow emission, indicating they may be prestellar cores. With a rich ALMA spectrum full of complex organic molecules, MM1 does not appear chemically young, but has molecular abundances typical of high-mass hot cores in the literature. At the 1.05 mm continuum peak of MM1, N(CH3OH) = (2.22 ± 0.01) × 1018 cm−2 and $T_{mathrm{ex}} = 162.7substack{+0.3 -0.5}$ K based on pixel-by-pixel Bayesian analysis of LTE synthetic methanol spectra across MM1. Intriguingly, the peak CH3OH Tex = 165.5 ± 0.6 K is offset from MM1’s millimetre continuum peak by 0.22″ ∼ 880 au, and a region of elevated CH3OH Tex coincides with free-free VLA 5.01 cm continuum, adding to the tentative evidence for a possible unresolved high-mass binary in MM1. In our VLA 1.21 cm data, we report the first NH3(3,3) maser detections towards G19.01−0.03, along with candidate 25 GHz CH3OH 5(2, 3) − 5(1, 4) maser emission; both are spatially and kinematically coincident with 44 GHz Class I CH3OH masers in the MM1 outflow. We also report the ALMA detection of candidate 278.3 GHz Class I CH3OH maser emission towards this outflow, strengthening the connection of these three maser types to MYSO outflows.
{"title":"ALMA observations of the Extended Green Object G19.01–0.03: ii. A massive protostar with typical chemical abundances surrounded by four low-mass prestellar core candidates","authors":"G. M. Williams, C. Cyganowski, C. Brogan, Todd R. Hunter, Pooneh Nazari, Rowan J. Smith","doi":"10.1093/mnras/stad2677","DOIUrl":"https://doi.org/10.1093/mnras/stad2677","url":null,"abstract":"\u0000 We present a study of the physical and chemical properties of the Extended Green Object (EGO) G19.01−0.03 using sub-arcsecond angular resolution Atacama Large Millimeter/submillimeter Array (ALMA) 1.05 mm and Karl G. Jansky Very Large Array (VLA) 1.21 cm data. G19.01−0.03 MM1, the millimetre source associated with the central massive young stellar object (MYSO), appeared isolated and potentially chemically young in previous Submillimeter Array observations. In our ∼0.4″-resolution ALMA data, MM1 has four low-mass millimetre companions within 0.12 pc, all lacking maser or outflow emission, indicating they may be prestellar cores. With a rich ALMA spectrum full of complex organic molecules, MM1 does not appear chemically young, but has molecular abundances typical of high-mass hot cores in the literature. At the 1.05 mm continuum peak of MM1, N(CH3OH) = (2.22 ± 0.01) × 1018 cm−2 and $T_{mathrm{ex}} = 162.7substack{+0.3 -0.5}$ K based on pixel-by-pixel Bayesian analysis of LTE synthetic methanol spectra across MM1. Intriguingly, the peak CH3OH Tex = 165.5 ± 0.6 K is offset from MM1’s millimetre continuum peak by 0.22″ ∼ 880 au, and a region of elevated CH3OH Tex coincides with free-free VLA 5.01 cm continuum, adding to the tentative evidence for a possible unresolved high-mass binary in MM1. In our VLA 1.21 cm data, we report the first NH3(3,3) maser detections towards G19.01−0.03, along with candidate 25 GHz CH3OH 5(2, 3) − 5(1, 4) maser emission; both are spatially and kinematically coincident with 44 GHz Class I CH3OH masers in the MM1 outflow. We also report the ALMA detection of candidate 278.3 GHz Class I CH3OH maser emission towards this outflow, strengthening the connection of these three maser types to MYSO outflows.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":" ","pages":""},"PeriodicalIF":4.8,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41550225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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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