Pub Date : 2025-01-03DOI: 10.1051/0004-6361/202452569
René D. Rohrmann
Magnetic fields break the symmetry of the interaction of atoms with photons with different polarizations, yielding chirality and anisotropy properties. The dependence of the absorption spectrum on the polarization, a phenomenon known as dichroism, is present in the atmosphere of magnetic white dwarfs. Its evaluation for processes in the continuum spectrum has been elusive so far due to the absence of appropriate ionization equilibrium models and incomplete data on photoionization cross sections. We combined rigorous solutions to the equilibrium of atomic populations with approximate cross sections to calculate the absolute opacity due to photoionization in a magnetized hydrogen gas. We predict a strong right-handed circularly polarized absorption (χ+) formed blueward of the cyclotron resonance for fields from about 14 to several hundred megagauss. In energies lower than the cyclotron fundamental, this absorption shows a deep trough with respect to linear and left-handed circular polarizations that steepens with the field strength. The jump in χ+ is due to the confluence of a large number of photoionization continua produced by right-handed circularly polarized transitions from atomic states with a nonnegative magnetic quantum number toward different Landau levels.
{"title":"Strong signature of right-handed circularly polarized photoionization close to the cyclotron line in the atmosphere of magnetic white dwarfs","authors":"René D. Rohrmann","doi":"10.1051/0004-6361/202452569","DOIUrl":"https://doi.org/10.1051/0004-6361/202452569","url":null,"abstract":"Magnetic fields break the symmetry of the interaction of atoms with photons with different polarizations, yielding chirality and anisotropy properties. The dependence of the absorption spectrum on the polarization, a phenomenon known as dichroism, is present in the atmosphere of magnetic white dwarfs. Its evaluation for processes in the continuum spectrum has been elusive so far due to the absence of appropriate ionization equilibrium models and incomplete data on photoionization cross sections. We combined rigorous solutions to the equilibrium of atomic populations with approximate cross sections to calculate the absolute opacity due to photoionization in a magnetized hydrogen gas. We predict a strong right-handed circularly polarized absorption (<i>χ<i/><sup>+<sup/>) formed blueward of the cyclotron resonance for fields from about 14 to several hundred megagauss. In energies lower than the cyclotron fundamental, this absorption shows a deep trough with respect to linear and left-handed circular polarizations that steepens with the field strength. The jump in <i>χ<i/><sup>+<sup/> is due to the confluence of a large number of photoionization continua produced by right-handed circularly polarized transitions from atomic states with a nonnegative magnetic quantum number toward different Landau levels.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"27 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142929408","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 : 2025-01-03DOI: 10.1051/0004-6361/202451322
Linxia He, Jianpeng Guo
As fast forward interplanetary (IP) shocks travel outward in the IP medium, they might encounter planetary bow shocks (BSs) and then propagate into the magnetosheath. The interaction of an IP shock with a BS could create a new discontinuity, which has been predicted by theory and simulations, and commonly observed at Earth. Nevertheless, it is still uncertain whether such a phenomenon occurs at unmagnetized planets like Mars. Here, we present the first experimental observation of a discontinuity-like structure that follows a transmitted IP shock within the Martian magnetosheath. This event was recorded by the MAVEN spacecraft on March 3, 2015. The comparison of spacecraft measurements with theoretical studies indicates that the discontinuity-like structure is a compound structure in nature, composed of the slow expansion wave, contact discontinuity, and slow shock, launched by the interaction of a fast IP shock with the Martian BS. The results shed light on the similarities between magnetized and unmagnetized planets in response to the passage of IP shocks.
{"title":"Observation of discontinuities accompanied by interplanetary shock within the Martian magnetosheath","authors":"Linxia He, Jianpeng Guo","doi":"10.1051/0004-6361/202451322","DOIUrl":"https://doi.org/10.1051/0004-6361/202451322","url":null,"abstract":"As fast forward interplanetary (IP) shocks travel outward in the IP medium, they might encounter planetary bow shocks (BSs) and then propagate into the magnetosheath. The interaction of an IP shock with a BS could create a new discontinuity, which has been predicted by theory and simulations, and commonly observed at Earth. Nevertheless, it is still uncertain whether such a phenomenon occurs at unmagnetized planets like Mars. Here, we present the first experimental observation of a discontinuity-like structure that follows a transmitted IP shock within the Martian magnetosheath. This event was recorded by the MAVEN spacecraft on March 3, 2015. The comparison of spacecraft measurements with theoretical studies indicates that the discontinuity-like structure is a compound structure in nature, composed of the slow expansion wave, contact discontinuity, and slow shock, launched by the interaction of a fast IP shock with the Martian BS. The results shed light on the similarities between magnetized and unmagnetized planets in response to the passage of IP shocks.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"78 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142929409","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 : 2025-01-03DOI: 10.1051/0004-6361/202452832
D. Barbato, D. Mesa, V. D’Orazi, S. Desidera, A. Ruggieri, J. Farinato, L. Marafatto, E. Carolo, D. Vassallo, S. Ertel, J. Hom, R. M. Anche, F. Battaini, A. Becker, M. Bergomi, F. Biondi, A. Cardwell, P. Cerpelloni, G. Chauvin, S. Chinellato, C. Desgrange, S. Di Filippo, M. Dima, T. S. Gomes Machado, R. Gratton, D. Greggio, Th. Henning, M. Kenworthy, F. Laudisio, C. Lazzoni, J. Leisenring, L. Lessio, A. Lorenzetto, L. Mohr, M. Montoya, G. Rodeghiero, J. Patience, J. Power, D. Ricci, K. K. R. Santhakumari, A. Sozzetti, G. Umbriaco, M. Vega Pallauta, V. Viotto, K. Wagner
Context. The synergy between different detection methods is a key asset in exoplanetology that allows the precise characterization of detected exoplanets and robust constraints even in the case of a non-detection. The interplay between imaging, radial velocities and astrometry has recently produced significant advancements in exoplanetary science.Aims. We report a first result of an ongoing survey performed with SHARK-NIR, the new high-contrast near-infrared imaging camera at the Large Binocular Telescope, in parallel with LBTI/LMIRCam in order to detect planetary companions around stars with a significant proper motion anomaly. We focus on HD 57625, a F8 star for which we determine a 4.8−2.9+3.7 Ga age, exhibiting significant astrometric acceleration and for which archival radial velocities indicate a previously undetected massive long-period companion.Methods. We analysed the imaging data we collected with SHARK-NIR and LMIRCam in synergy with the available public SOPHIE radial velocity time series and HIPPARCOS-Gaia proper motion anomaly. With this joint multi-technique analysis, we characterised the companion causing the astrometric and radial velocity signals.Results. The imaging observations result in a non-detection, indicating the companion to be in the substellar regime. This is confirmed by the synergic analysis of archival radial velocity and astrometric measurements resulting in the detection of HD 57625 b, a 8.43−0.91+1.1 MJup planetary companion with an orbital separation of 5.70−0.13+0.14 au and an eccentricity of 0.52−0.03+0.04.Conclusions. HD 57625 b joins the small but growing population of giant planets on outer orbits with a true mass determination provided by the synergic usage of multiple detection methods. This again proves the importance of a multi-technique analysis in providing a robust characterization of planetary companions.
{"title":"A multi-technique detection of an eccentric giant planet around the accelerating star HD 57625","authors":"D. Barbato, D. Mesa, V. D’Orazi, S. Desidera, A. Ruggieri, J. Farinato, L. Marafatto, E. Carolo, D. Vassallo, S. Ertel, J. Hom, R. M. Anche, F. Battaini, A. Becker, M. Bergomi, F. Biondi, A. Cardwell, P. Cerpelloni, G. Chauvin, S. Chinellato, C. Desgrange, S. Di Filippo, M. Dima, T. S. Gomes Machado, R. Gratton, D. Greggio, Th. Henning, M. Kenworthy, F. Laudisio, C. Lazzoni, J. Leisenring, L. Lessio, A. Lorenzetto, L. Mohr, M. Montoya, G. Rodeghiero, J. Patience, J. Power, D. Ricci, K. K. R. Santhakumari, A. Sozzetti, G. Umbriaco, M. Vega Pallauta, V. Viotto, K. Wagner","doi":"10.1051/0004-6361/202452832","DOIUrl":"https://doi.org/10.1051/0004-6361/202452832","url":null,"abstract":"<i>Context.<i/> The synergy between different detection methods is a key asset in exoplanetology that allows the precise characterization of detected exoplanets and robust constraints even in the case of a non-detection. The interplay between imaging, radial velocities and astrometry has recently produced significant advancements in exoplanetary science.<i>Aims.<i/> We report a first result of an ongoing survey performed with SHARK-NIR, the new high-contrast near-infrared imaging camera at the Large Binocular Telescope, in parallel with LBTI/LMIRCam in order to detect planetary companions around stars with a significant proper motion anomaly. We focus on HD 57625, a F8 star for which we determine a 4.8<sub>−2.9<sub/><sup>+3.7<sup/> Ga age, exhibiting significant astrometric acceleration and for which archival radial velocities indicate a previously undetected massive long-period companion.<i>Methods.<i/> We analysed the imaging data we collected with SHARK-NIR and LMIRCam in synergy with the available public SOPHIE radial velocity time series and HIPPARCOS-<i>Gaia<i/> proper motion anomaly. With this joint multi-technique analysis, we characterised the companion causing the astrometric and radial velocity signals.<i>Results.<i/> The imaging observations result in a non-detection, indicating the companion to be in the substellar regime. This is confirmed by the synergic analysis of archival radial velocity and astrometric measurements resulting in the detection of HD 57625 b, a 8.43<sub>−0.91<sub/><sup>+1.1<sup/> M<sub>Jup<sub/> planetary companion with an orbital separation of 5.70<sub>−0.13<sub/><sup>+0.14<sup/> au and an eccentricity of 0.52<sub>−0.03<sub/><sup>+0.04<sup/>.<i>Conclusions.<i/> HD 57625 b joins the small but growing population of giant planets on outer orbits with a true mass determination provided by the synergic usage of multiple detection methods. This again proves the importance of a multi-technique analysis in providing a robust characterization of planetary companions.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"117 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142929383","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 : 2025-01-03DOI: 10.1051/0004-6361/202452686
R. Cesaroni, D. Galli, M. Padovani, V. M. Rivilla, Á. Sánchez-Monge
Context. The study of disks around early-type (proto)stars has recently been boosted by a new generation of instruments, and additional evidence has been found of disk+jet systems around stars of up to ~20 M⊙. These results appear to confirm theoretical predictions that even the most massive stars may form though disk-mediated accretion.Aims. We want to investigate one of the best examples of disk+jet systems around an early B-type (proto)star, IRAS 20126+4104. The relatively simple structure of this object and its relative proximity to Earth (1.64 kpc) make it an ideal target for resolution of its disk and the determination of its physical and kinematical structure.Methods. Despite the high declination of IRAS 20126+4104, it has been possible to perform successful observations with the Atacama Large Millimeter and submillimeter Array at 1.4 mm in the continuum emission and a number of molecular tracers of high-density gas (for the disk) and shocked gas (for the jet).Results. The new data allow us to improve on previous similar observations of IRAS 20126+4104 and confirm the existence of a Keplerian accretion disk around a ~12 M⊙ (proto)star. From methyl cyanide, we derived the rotation temperature and column density as a function of disk radius. We also obtained a map of the same quantities for the jet using the ratio between two lines of formaldehyde. We also use two simple models of the jet and the disk to estimate the basic geometrical and kinematical parameters of the two. From the temperature and column density profiles, we conclude that the disk is stable at all radii. We also estimate an accretion rate of ~10−3M⊙ yr−1.Conclusions. Our analysis confirms that the jet from IRAS 20126+4104 is highly collimated, lies close to the plane of the sky, and expands with velocity increasing with distance. As expected, the gas temperature and column density peak in the bow shock. The disk is undergoing Keplerian rotation but a non-negligible radial velocity component is also present that is equal to ~40% of the rotational component. The disk is slightly inclined with respect to the line of sight and has a dusty envelope that absorbs the emission from the disk surface. This causes a slight distortion of the disk structure observed in high-density tracers such as methyl cyanide. We also reveal a significant deviation from axial symmetry in the SW part of the disk, which might be caused by either tidal interaction with a nearby, lower-mass companion or interaction with the outflowing gas of the jet.
{"title":"Dissecting the disk and the jet of a massive (proto)star","authors":"R. Cesaroni, D. Galli, M. Padovani, V. M. Rivilla, Á. Sánchez-Monge","doi":"10.1051/0004-6361/202452686","DOIUrl":"https://doi.org/10.1051/0004-6361/202452686","url":null,"abstract":"<i>Context.<i/> The study of disks around early-type (proto)stars has recently been boosted by a new generation of instruments, and additional evidence has been found of disk+jet systems around stars of up to ~20 <i>M<i/><sub>⊙<sub/>. These results appear to confirm theoretical predictions that even the most massive stars may form though disk-mediated accretion.<i>Aims.<i/> We want to investigate one of the best examples of disk+jet systems around an early B-type (proto)star, IRAS 20126+4104. The relatively simple structure of this object and its relative proximity to Earth (1.64 kpc) make it an ideal target for resolution of its disk and the determination of its physical and kinematical structure.<i>Methods.<i/> Despite the high declination of IRAS 20126+4104, it has been possible to perform successful observations with the Atacama Large Millimeter and submillimeter Array at 1.4 mm in the continuum emission and a number of molecular tracers of high-density gas (for the disk) and shocked gas (for the jet).<i>Results.<i/> The new data allow us to improve on previous similar observations of IRAS 20126+4104 and confirm the existence of a Keplerian accretion disk around a ~12 <i>M<i/><sub>⊙<sub/> (proto)star. From methyl cyanide, we derived the rotation temperature and column density as a function of disk radius. We also obtained a map of the same quantities for the jet using the ratio between two lines of formaldehyde. We also use two simple models of the jet and the disk to estimate the basic geometrical and kinematical parameters of the two. From the temperature and column density profiles, we conclude that the disk is stable at all radii. We also estimate an accretion rate of ~10<sup>−3<sup/> <i>M<i/><sub>⊙<sub/> yr<sup>−1<sup/>.<i>Conclusions.<i/> Our analysis confirms that the jet from IRAS 20126+4104 is highly collimated, lies close to the plane of the sky, and expands with velocity increasing with distance. As expected, the gas temperature and column density peak in the bow shock. The disk is undergoing Keplerian rotation but a non-negligible radial velocity component is also present that is equal to ~40% of the rotational component. The disk is slightly inclined with respect to the line of sight and has a dusty envelope that absorbs the emission from the disk surface. This causes a slight distortion of the disk structure observed in high-density tracers such as methyl cyanide. We also reveal a significant deviation from axial symmetry in the SW part of the disk, which might be caused by either tidal interaction with a nearby, lower-mass companion or interaction with the outflowing gas of the jet.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"5 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142929415","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 : 2025-01-03DOI: 10.1051/0004-6361/202451140
Alex J. Cridland, Elena Lega, Myriam Benisty
The link between the chemistry of the protoplanetary disk and the properties of the resulting planets have long been a subject of interest in the effort to understand planet formation. These connections have generally been made between mature planets and young protoplanetary disks through the carbon-to-oxygen (C/O) ratio. In a rare number of systems, young protoplanets have been found within their natal protoplanetary disks. These systems offer a unique opportunity to directly study the delivery of gas from the protoplanetary disk to the planet. In this work we post-process 3D numerical simulations of an embedded Jupiter-mass planet in its protoplanetary disk to explore the chemical evolution of gas as it flows from the disk to the planet. The relevant dust to this chemical evolution is assumed to be small co-moving grains with a reduced dust-to-gas ratio indicative of the upper atmosphere of a protoplanetary disk. We find that as the gas enters deep into the planet’s gravitational well, it warms significantly (up to ~800 K), releasing all of the volatile content from the ice phase. This change in phase can influence our understanding of the delivery of volatile species to the atmospheres of giant planets. The primary carbon, oxygen, and sulphur carrying ices (CO2, H2O, and H2S) are released into the gas phase and along with the warm gas temperatures near the embedded planets lead to the production of unique species such as CS, SO, and SO2 compared to the protoplanetary disk. We compute the column densities of SO, SO2, CS, and H2CS in our model and find that their values are consistent with previous observational studies.
{"title":"Gas dynamics around a Jupiter-mass planet","authors":"Alex J. Cridland, Elena Lega, Myriam Benisty","doi":"10.1051/0004-6361/202451140","DOIUrl":"https://doi.org/10.1051/0004-6361/202451140","url":null,"abstract":"The link between the chemistry of the protoplanetary disk and the properties of the resulting planets have long been a subject of interest in the effort to understand planet formation. These connections have generally been made between mature planets and young protoplanetary disks through the carbon-to-oxygen (C/O) ratio. In a rare number of systems, young protoplanets have been found within their natal protoplanetary disks. These systems offer a unique opportunity to directly study the delivery of gas from the protoplanetary disk to the planet. In this work we post-process 3D numerical simulations of an embedded Jupiter-mass planet in its protoplanetary disk to explore the chemical evolution of gas as it flows from the disk to the planet. The relevant dust to this chemical evolution is assumed to be small co-moving grains with a reduced dust-to-gas ratio indicative of the upper atmosphere of a protoplanetary disk. We find that as the gas enters deep into the planet’s gravitational well, it warms significantly (up to ~800 K), releasing all of the volatile content from the ice phase. This change in phase can influence our understanding of the delivery of volatile species to the atmospheres of giant planets. The primary carbon, oxygen, and sulphur carrying ices (CO<sub>2<sub/>, H<sub>2<sub/>O, and H<sub>2<sub/>S) are released into the gas phase and along with the warm gas temperatures near the embedded planets lead to the production of unique species such as CS, SO, and SO<sub>2<sub/> compared to the protoplanetary disk. We compute the column densities of SO, SO<sub>2<sub/>, CS, and H<sub>2<sub/>CS in our model and find that their values are consistent with previous observational studies.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"4 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142929412","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 : 2024-12-20DOI: 10.1051/0004-6361/202348575
Conny Aerts, Andrew Tkachenko
Rotation matters for the life of a star. It causes a multitude of dynamical phenomena in the stellar interior during a star’s evolution, and its effects accumulate until the star dies. All stars rotate at some level, but most of those born with a mass higher than 1.3 times the mass of the Sun rotate rapidly during more than 90% of their nuclear lifetime. Internal rotation guides the angular momentum and chemical element transport throughout the stellar interior. These transport processes change over time as the star evolves. The cumulative effects of stellar rotation and its induced transport processes determine the helium content of the core by the time it exhausts its hydrogen isotopes. The amount of helium at that stage also guides the heavy element yields by the end of the star’s life. A proper theory of stellar evolution and any realistic models for the chemical enrichment of galaxies must be based on observational calibrations of stellar rotation and of the induced transport processes. In the last few years, asteroseismology offers such calibrations for single and binary stars. We review the current status of asteroseismic modelling of rotating stars for different stellar mass regimes in an accessible way for the non-expert. While doing so, we describe exciting opportunities sparked by asteroseismology for various domains in astrophysics, touching upon topics such as exoplanetary science, galactic structure and evolution, and gravitational wave physics to mention just a few. Along the way we provide ample sneak-previews for future ‘industrialised’ applications of asteroseismology to slow and rapid rotators from the exploitation of combined Kepler, Transiting Exoplanet Survey Satellite (TESS), PLAnetary Transits and Oscillations of stars (PLATO), Gaia, and ground-based spectroscopic and multi-colour photometric surveys. We end the review with a list of takeaway messages and achievements of asteroseismology that are of relevance for many fields of astrophysics.
{"title":"Asteroseismic modelling of fast rotators and its opportunities for astrophysics","authors":"Conny Aerts, Andrew Tkachenko","doi":"10.1051/0004-6361/202348575","DOIUrl":"https://doi.org/10.1051/0004-6361/202348575","url":null,"abstract":"Rotation matters for the life of a star. It causes a multitude of dynamical phenomena in the stellar interior during a star’s evolution, and its effects accumulate until the star dies. All stars rotate at some level, but most of those born with a mass higher than 1.3 times the mass of the Sun rotate rapidly during more than 90% of their nuclear lifetime. Internal rotation guides the angular momentum and chemical element transport throughout the stellar interior. These transport processes change over time as the star evolves. The cumulative effects of stellar rotation and its induced transport processes determine the helium content of the core by the time it exhausts its hydrogen isotopes. The amount of helium at that stage also guides the heavy element yields by the end of the star’s life. A proper theory of stellar evolution and any realistic models for the chemical enrichment of galaxies must be based on observational calibrations of stellar rotation and of the induced transport processes. In the last few years, asteroseismology offers such calibrations for single and binary stars. We review the current status of asteroseismic modelling of rotating stars for different stellar mass regimes in an accessible way for the non-expert. While doing so, we describe exciting opportunities sparked by asteroseismology for various domains in astrophysics, touching upon topics such as exoplanetary science, galactic structure and evolution, and gravitational wave physics to mention just a few. Along the way we provide ample sneak-previews for future ‘industrialised’ applications of asteroseismology to slow and rapid rotators from the exploitation of combined <i>Kepler<i/>, Transiting Exoplanet Survey Satellite (TESS), PLAnetary Transits and Oscillations of stars (PLATO), <i>Gaia<i/>, and ground-based spectroscopic and multi-colour photometric surveys. We end the review with a list of takeaway messages and achievements of asteroseismology that are of relevance for many fields of astrophysics.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"19 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142874534","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 : 2024-12-19DOI: 10.1051/0004-6361/202451659
G. Sabatini, S. Bovino, E. Redaelli, F. Wyrowski, J. S. Urquhart, A. Giannetti, J. Brand, K. M. Menten
Context. Deuterium fractionation is a well-established evolutionary tracer in low-mass star formation, but its applicability to the high-mass regime remains an open question. In this context, the abundances and ratios of different deuterated species have often been proposed as reliable evolutionary indicators for different stages of the high-mass star formation process.Aims. In this study, we investigate the role of N2H+ and key deuterated molecules (o-H2D+ and N2D+) as tracers of the different stages of the high-mass star formation process. We assess whether their abundance ratios can serve as reliable evolutionary indicators.Methods. We conducted APEX observations of o-H2D+ (110–111), N2H+ (4−3), and N2D+ (3−2) in a sample of 40 high-mass clumps at different evolutionary stages, selected from the ATLASGAL survey. Molecular column densities and abundances relative to H2, X, were derived through spectral line modelling, both under local thermodynamic equilibrium (LTE) and non-LTE conditions.Results. The o-H2D+ column densities show the smallest deviation from LTE conditions when derived under non-LTE assumptions. In contrast, N2H+ shows the largest discrepancy between the column densities derived from LTE and non-LTE. In all the cases discussed, we found that X(o-H2D+) decreases more significantly with each respective evolutionary stage than in the case of X(N2D+); whereas X(N2H+) increases slightly. Therefore, the validity of the X(o-H2D+)/X(N2D+) ratio as a reliable evolutionary indicator, recently proposed as a promising tracer of the different evolutionary stages, was not observed for this sample. While the deuteration fraction derived from N2D+ and N2H+ clearly decreases with clump evolution, the interpretation of this trend is complex, given the different distribution of the two tracers.Conclusions. Our results suggest that a careful consideration of the observational biases and beam-dilution effects are crucial for an accurate interpretation of the evolution of the deuteration process during the high-mass star formation process.
{"title":"Time evolution of o-H2D+, N2D+, and N2H+ during the high-mass star formation process","authors":"G. Sabatini, S. Bovino, E. Redaelli, F. Wyrowski, J. S. Urquhart, A. Giannetti, J. Brand, K. M. Menten","doi":"10.1051/0004-6361/202451659","DOIUrl":"https://doi.org/10.1051/0004-6361/202451659","url":null,"abstract":"<i>Context<i/>. Deuterium fractionation is a well-established evolutionary tracer in low-mass star formation, but its applicability to the high-mass regime remains an open question. In this context, the abundances and ratios of different deuterated species have often been proposed as reliable evolutionary indicators for different stages of the high-mass star formation process.<i>Aims<i/>. In this study, we investigate the role of N<sub>2<sub/>H+ and key deuterated molecules (o-H<sub>2<sub/>D<sup>+<sup/> and N<sub>2<sub/>D<sup>+<sup/>) as tracers of the different stages of the high-mass star formation process. We assess whether their abundance ratios can serve as reliable evolutionary indicators.<i>Methods<i/>. We conducted APEX observations of o-H<sub>2<sub/>D<sup>+<sup/> (1<sub>10<sub/>–1<sub>11<sub/>), N<sub>2<sub/>H<sup>+<sup/> (4−3), and N<sub>2<sub/>D<sup>+<sup/> (3−2) in a sample of 40 high-mass clumps at different evolutionary stages, selected from the ATLASGAL survey. Molecular column densities and abundances relative to H<sub>2<sub/>, <i>X<i/>, were derived through spectral line modelling, both under local thermodynamic equilibrium (LTE) and non-LTE conditions.<i>Results<i/>. The o-H<sub>2<sub/>D<sup>+<sup/> column densities show the smallest deviation from LTE conditions when derived under non-LTE assumptions. In contrast, N<sub>2<sub/>H<sup>+<sup/> shows the largest discrepancy between the column densities derived from LTE and non-LTE. In all the cases discussed, we found that <i>X<i/>(o-H<sub>2<sub/>D<sup>+<sup/>) decreases more significantly with each respective evolutionary stage than in the case of <i>X<i/>(N<sub>2<sub/>D<sup>+<sup/>); whereas <i>X<i/>(N<sub>2<sub/>H<sup>+<sup/>) increases slightly. Therefore, the validity of the <i>X<i/>(o-H<sub>2<sub/>D<sup>+<sup/>)/<i>X<i/>(N<sub>2<sub/>D<sup>+<sup/>) ratio as a reliable evolutionary indicator, recently proposed as a promising tracer of the different evolutionary stages, was not observed for this sample. While the deuteration fraction derived from N<sub>2<sub/>D<sup>+<sup/> and N<sub>2<sub/>H<sup>+<sup/> clearly decreases with clump evolution, the interpretation of this trend is complex, given the different distribution of the two tracers.<i>Conclusions<i/>. Our results suggest that a careful consideration of the observational biases and beam-dilution effects are crucial for an accurate interpretation of the evolution of the deuteration process during the high-mass star formation process.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"23 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142857551","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 : 2024-12-19DOI: 10.1051/0004-6361/202346886
C. J. Nelson, L. A. Hayes, D. Müller, S. Musset, N. Freij, F. Auchère, R. Aznar Cuadrado, K. Barczynski, E. Buchlin, L. Harra, D. M. Long, S. Parenti, H. Peter, U. Schühle, P. Smith, L. Teriaca, C. Verbeeck, A. N. Zhukov, D. Berghmans
Context. The identification of large numbers of localised transient extreme ultraviolet (EUV) brightenings, on very small spatial scales, in the quiet Sun corona has been one of the key early results from Solar Orbiter. However, there are still a great deal of unknowns about these events.Aims. In this work, we aim to better understand EUV brightenings by investigating their spatial distributions. Specifically, we have investigated whether they occur co-spatially with specific line-of-sight (LoS) magnetic field topologies in the photospheric network.Methods. We detected the EUV brightenings in this work using an automated algorithm applied to a high-cadence (3 s) dataset sampled over ∼30 minutes on 8 March 2022 by the Extreme Ultraviolet Imager’s 17.4 nm EUV High Resolution Imager (HRIEUV). Data from the Solar Dynamics Observatory’s Helioseismic and Magnetic Imager (SDO/HMI) and Atmospheric Imaging Assembly (SDO/AIA) were used to provide context on the LoS magnetic field and for alignment purposes, respectively.Results. We found a total of 5064 EUV brightenings within this dataset that are directly comparable to events reported previously in the literature. These events occurred within around 0.015–0.020% of pixels for any given frame. We compared eight different thresholds to split the EUV brightenings into four different categories related to the LoS magnetic field. Using our preferred threshold, we found that 627 EUV brightenings (12.4%) occurred co-spatially with strong bipolar configurations and 967 EUV brightenings (19.1%) occurred in weak field regions. Fewer than 10% of EUV brightenings occurred co-spatially with the unipolar LoS magnetic field, no matter what threshold was used. Of the 627 strong bipolar EUV Brightenings, 54 were found to occur co-spatially with cancellation, whilst 57 occurred co-spatially with emergence.Conclusions. EUV brightenings are primarily found to occur co-spatially with the strong LoS magnetic field in the photospheric network. However, they do not predominantly occur co-spatially with (cancelling) bi-poles.
{"title":"Spatial distributions of extreme-ultraviolet brightenings in the quiet Sun","authors":"C. J. Nelson, L. A. Hayes, D. Müller, S. Musset, N. Freij, F. Auchère, R. Aznar Cuadrado, K. Barczynski, E. Buchlin, L. Harra, D. M. Long, S. Parenti, H. Peter, U. Schühle, P. Smith, L. Teriaca, C. Verbeeck, A. N. Zhukov, D. Berghmans","doi":"10.1051/0004-6361/202346886","DOIUrl":"https://doi.org/10.1051/0004-6361/202346886","url":null,"abstract":"<i>Context.<i/> The identification of large numbers of localised transient extreme ultraviolet (EUV) brightenings, on very small spatial scales, in the quiet Sun corona has been one of the key early results from Solar Orbiter. However, there are still a great deal of unknowns about these events.<i>Aims.<i/> In this work, we aim to better understand EUV brightenings by investigating their spatial distributions. Specifically, we have investigated whether they occur co-spatially with specific line-of-sight (LoS) magnetic field topologies in the photospheric network.<i>Methods.<i/> We detected the EUV brightenings in this work using an automated algorithm applied to a high-cadence (3 s) dataset sampled over ∼30 minutes on 8 March 2022 by the Extreme Ultraviolet Imager’s 17.4 nm EUV High Resolution Imager (HRI<sub>EUV<sub/>). Data from the Solar Dynamics Observatory’s Helioseismic and Magnetic Imager (SDO/HMI) and Atmospheric Imaging Assembly (SDO/AIA) were used to provide context on the LoS magnetic field and for alignment purposes, respectively.<i>Results.<i/> We found a total of 5064 EUV brightenings within this dataset that are directly comparable to events reported previously in the literature. These events occurred within around 0.015–0.020% of pixels for any given frame. We compared eight different thresholds to split the EUV brightenings into four different categories related to the LoS magnetic field. Using our preferred threshold, we found that 627 EUV brightenings (12.4%) occurred co-spatially with strong bipolar configurations and 967 EUV brightenings (19.1%) occurred in weak field regions. Fewer than 10% of EUV brightenings occurred co-spatially with the unipolar LoS magnetic field, no matter what threshold was used. Of the 627 strong bipolar EUV Brightenings, 54 were found to occur co-spatially with cancellation, whilst 57 occurred co-spatially with emergence.<i>Conclusions.<i/> EUV brightenings are primarily found to occur co-spatially with the strong LoS magnetic field in the photospheric network. However, they do not predominantly occur co-spatially with (cancelling) bi-poles.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"28 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142857548","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 : 2024-12-18DOI: 10.1051/0004-6361/202451451
Eduard Keilmann, Slawa Kabanovic, Nicola Schneider, Volker Ossenkopf-Okada, Jürgen Stutzki, Masato I. N. Kobayashi, Robert Simon, Christof Buchbender, Dominik Riechers, Frank Bigiel, Fatemeh Tabatabaei
Understanding the physical properties such as mass, size, and surface mass density of giant molecular clouds or associations (GMCs/GMAs) in galaxies is crucial for gaining deeper insights into the molecular cloud and star formation (SF) processes. We determine these quantities for the Local Group flocculent spiral galaxy M33 using Herschel dust and archival 12CO(2 − 1) data from the IRAM 30 m telescope, and compare them to GMC/GMA properties of the Milky Way derived from CO literature data. For M33, we apply the Dendrogram algorithm on a novel 2D dust-derived NH2 map at an angular resolution of 18.2″ and on the 12CO(2 − 1) data and employ an XCO factor map instead of a constant value. Dust and CO-derived values are similar, with mean radii of ∼58 pc for the dust and ∼68 pc for CO, respectively. However, the largest GMAs have a radius of around 150 pc, similar to what was found in the Milky Way and other galaxies, suggesting a physical process that limits the size of GMAs. The less massive and smaller M33 galaxy also hosts less massive and lower-density GMCs compared to the Milky Way by an order of magnitude. Notably, the most massive (> a few 106 M⊙) GMC population observed in the Milky Way is mainly missing in M33. The mean surface mass density of M33 is significantly smaller than that of the Milky Way and this is attributed to higher column densities of the largest GMCs in the Milky Way, despite similar GMC areas. We find no systematic gradients in physical properties with the galactocentric radius in M33. However, surface mass densities and masses are higher near the center, implying increased SF activity. In both galaxies, the central region contains ∼30% of the total molecular mass. The index of the power-law spectrum of the GMC masses across the entire disk of M33 is α = 2.3 ± 0.1 and α = 1.9 ± 0.1 for dust- and CO-derived data, respectively. We conclude that GMC properties in M33 and the Milky Way are largely similar, though M33 lacks high-mass GMCs, for which there is no straightforward explanation. Additionally, GMC properties are only weakly dependent on the galactic environment, with stellar feedback playing a role that needs further investigation.
{"title":"Molecular cloud matching in CO and dust in M33","authors":"Eduard Keilmann, Slawa Kabanovic, Nicola Schneider, Volker Ossenkopf-Okada, Jürgen Stutzki, Masato I. N. Kobayashi, Robert Simon, Christof Buchbender, Dominik Riechers, Frank Bigiel, Fatemeh Tabatabaei","doi":"10.1051/0004-6361/202451451","DOIUrl":"https://doi.org/10.1051/0004-6361/202451451","url":null,"abstract":"Understanding the physical properties such as mass, size, and surface mass density of giant molecular clouds or associations (GMCs/GMAs) in galaxies is crucial for gaining deeper insights into the molecular cloud and star formation (SF) processes. We determine these quantities for the Local Group flocculent spiral galaxy M33 using H<i>erschel<i/> dust and archival <sup>12<sup/>CO(2 − 1) data from the IRAM 30 m telescope, and compare them to GMC/GMA properties of the Milky Way derived from CO literature data. For M33, we apply the Dendrogram algorithm on a novel 2D dust-derived <i>N<i/><sub>H<sub>2<sub/><sub/> map at an angular resolution of 18.2″ and on the <sup>12<sup/>CO(2 − 1) data and employ an <i>X<i/><sub>CO<sub/> factor map instead of a constant value. Dust and CO-derived values are similar, with mean radii of ∼58 pc for the dust and ∼68 pc for CO, respectively. However, the largest GMAs have a radius of around 150 pc, similar to what was found in the Milky Way and other galaxies, suggesting a physical process that limits the size of GMAs. The less massive and smaller M33 galaxy also hosts less massive and lower-density GMCs compared to the Milky Way by an order of magnitude. Notably, the most massive (> a few 10<sup>6<sup/> M<sub>⊙<sub/>) GMC population observed in the Milky Way is mainly missing in M33. The mean surface mass density of M33 is significantly smaller than that of the Milky Way and this is attributed to higher column densities of the largest GMCs in the Milky Way, despite similar GMC areas. We find no systematic gradients in physical properties with the galactocentric radius in M33. However, surface mass densities and masses are higher near the center, implying increased SF activity. In both galaxies, the central region contains ∼30% of the total molecular mass. The index of the power-law spectrum of the GMC masses across the entire disk of M33 is <i>α<i/> = 2.3 ± 0.1 and <i>α<i/> = 1.9 ± 0.1 for dust- and CO-derived data, respectively. We conclude that GMC properties in M33 and the Milky Way are largely similar, though M33 lacks high-mass GMCs, for which there is no straightforward explanation. Additionally, GMC properties are only weakly dependent on the galactic environment, with stellar feedback playing a role that needs further investigation.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"7 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142849033","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 : 2024-12-18DOI: 10.1051/0004-6361/202452383
M. Ziv, E. Galanti, S. Howard, T. Guillot, Y. Kaspi
Context. The internal structure of Jupiter is constrained by the precise gravity field measurements by NASA’s Juno mission, atmospheric data from the Galileo entry probe, and Voyager radio occultations. Not only are these observations few compared to the possible interior setups and their multiple controlling parameters, but they remain challenging to reconcile. As a complex, multidimensional problem, characterizing typical structures can help simplify the modeling process.Aims. We explored the plausible range of Jupiter’s interior structures using a coupled interior and wind model, identifying key structures and effective parameters to simplify its multidimensional representation.Methods. We used NeuralCMS, a deep learning model based on the accurate concentric Maclaurin spheroid (CMS) method, coupled with a fully consistent wind model to efficiently explore a wide range of interior models without prior assumptions. We then identified those consistent with the measurements and clustered the plausible combinations of parameters controlling the interior.Results. We determine the plausible ranges of internal structures and the dynamical contributions to Jupiter’s gravity field. Four typical interior structures are identified, characterized by their envelope and core properties. This reduces the dimensionality of Jupiter’s interior to only two effective parameters. Within the reduced 2D phase space, we show that the most observationally constrained structures fall within one of the key structures, but they require a higher 1 bar temperature than the observed value.Conclusions. We provide a robust framework for characterizing giant planet interiors with consistent wind treatment, demonstrating that for Jupiter, wind constraints strongly impact the gravity harmonics while the interior parameter distribution remains largely unchanged. Importantly, we find that Jupiter’s interior can be described by two effective parameters that clearly distinguish the four characteristic structures and conclude that atmospheric measurements may not fully represent the entire envelope.
{"title":"Characterizing Jupiter’s interior using machine learning reveals four key structures","authors":"M. Ziv, E. Galanti, S. Howard, T. Guillot, Y. Kaspi","doi":"10.1051/0004-6361/202452383","DOIUrl":"https://doi.org/10.1051/0004-6361/202452383","url":null,"abstract":"<i>Context<i/>. The internal structure of Jupiter is constrained by the precise gravity field measurements by NASA’s Juno mission, atmospheric data from the Galileo entry probe, and Voyager radio occultations. Not only are these observations few compared to the possible interior setups and their multiple controlling parameters, but they remain challenging to reconcile. As a complex, multidimensional problem, characterizing typical structures can help simplify the modeling process.<i>Aims<i/>. We explored the plausible range of Jupiter’s interior structures using a coupled interior and wind model, identifying key structures and effective parameters to simplify its multidimensional representation.<i>Methods<i/>. We used NeuralCMS, a deep learning model based on the accurate concentric Maclaurin spheroid (CMS) method, coupled with a fully consistent wind model to efficiently explore a wide range of interior models without prior assumptions. We then identified those consistent with the measurements and clustered the plausible combinations of parameters controlling the interior.<i>Results<i/>. We determine the plausible ranges of internal structures and the dynamical contributions to Jupiter’s gravity field. Four typical interior structures are identified, characterized by their envelope and core properties. This reduces the dimensionality of Jupiter’s interior to only two effective parameters. Within the reduced 2D phase space, we show that the most observationally constrained structures fall within one of the key structures, but they require a higher 1 bar temperature than the observed value.<i>Conclusions<i/>. We provide a robust framework for characterizing giant planet interiors with consistent wind treatment, demonstrating that for Jupiter, wind constraints strongly impact the gravity harmonics while the interior parameter distribution remains largely unchanged. Importantly, we find that Jupiter’s interior can be described by two effective parameters that clearly distinguish the four characteristic structures and conclude that atmospheric measurements may not fully represent the entire envelope.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"7 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142848989","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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