Pub Date : 2021-08-30DOI: 10.1051/0004-6361/202141128
H. Zhao, M. Schultheis, Á. Rojas-Arriagada, A. Recio-Blanco, P. Laverny, G. Kordopatis, F. Surot
Context. Diffuse interstellar bands (DIBs) are important interstellar absorption features of which the origin is still debated. With the large data sets from modern spectroscopic surveys, background stars are widely used to show how the integrated columns of DIB carriers accumulate from the Sun to great distances. To date, studies on the kinematics of the DIB carriers are still rare. Aims. We aim to make use of the measurements from the Giraffe Inner Bulge Survey (GIBS) and the Gaia–ESO survey (GES) to study the kinematics and distance of the carrier of DIB λ8620, as well as other properties. Methods. The DIBs were detected and measured following the same procedures as in Zhao et al. (2021, A&A, 645, A14; hereafter Paper I), assuming a Gaussian profile. The median radial velocities of the DIB carriers in 38 GIBS and GES fields were used to trace their kinematics, and the median distances of the carriers in each field were estimated by the median radial velocities and two applied Galactic rotation models. Results. We successfully detected and measured DIB λ8620 in 760 of 4117 GES spectra with |b|6 10◦ and signal-to-noise ratio (S/N) > 50. Combined with the DIBs measured in GIBS spectra (Paper I), we confirmed a tight relation between EW and E(J −KS) as well as AV, with similar fitting coefficients to those found by previous works. With a more accurate sample and the consideration of the solar motion, the rest-frame wavelength of DIB λ8620 was redetermined as 8620.83 Å, with a mean fit error of 0.36 Å. We studied the kinematics of the DIB carriers by tracing their median radial velocities in each field in the local standard of rest (VLSR) and into the galactocentric frame (VGC), respectively, as a function of the Galactic longitudes. Based on the median VLSR and two Galactic rotation models, we obtained valid kinematic distances of the DIB carriers for nine GIBS and ten GES fields. We also found a linear relation between the DIB λ8620 measured in this work and the near-infrared DIB in APOGEE spectra at 1.5273μm, and we estimated the carrier abundance to be slightly lower compared to the DIB λ15273. Conclusions. We demonstrate that the DIB carriers can be located much closer to the observer than the background stars based on the following arguments: (i) qualitatively, the carriers occupy in the Galactic longitude–velocity diagram typical rotation velocities of stars in the local Galactic disk, while the background stars in the GIBS survey are mainly located in the Galactic bulge; (ii) quantitatively, all the derived kinematic distances of the DIB carriers are smaller than the median distances to background stars in each field. A linear correlation between DIB λ8620 and DIB λ15273 has been established, showing similar carrier abundances and making them both attractive for future studies of the interstellar environments.
{"title":"The diffuse interstellar band around 8620 Å. II. Kinematics and distance of the DIB carrier","authors":"H. Zhao, M. Schultheis, Á. Rojas-Arriagada, A. Recio-Blanco, P. Laverny, G. Kordopatis, F. Surot","doi":"10.1051/0004-6361/202141128","DOIUrl":"https://doi.org/10.1051/0004-6361/202141128","url":null,"abstract":"Context. Diffuse interstellar bands (DIBs) are important interstellar absorption features of which the origin is still debated. With the large data sets from modern spectroscopic surveys, background stars are widely used to show how the integrated columns of DIB carriers accumulate from the Sun to great distances. To date, studies on the kinematics of the DIB carriers are still rare. Aims. We aim to make use of the measurements from the Giraffe Inner Bulge Survey (GIBS) and the Gaia–ESO survey (GES) to study the kinematics and distance of the carrier of DIB λ8620, as well as other properties. Methods. The DIBs were detected and measured following the same procedures as in Zhao et al. (2021, A&A, 645, A14; hereafter Paper I), assuming a Gaussian profile. The median radial velocities of the DIB carriers in 38 GIBS and GES fields were used to trace their kinematics, and the median distances of the carriers in each field were estimated by the median radial velocities and two applied Galactic rotation models. Results. We successfully detected and measured DIB λ8620 in 760 of 4117 GES spectra with |b|6 10◦ and signal-to-noise ratio (S/N) > 50. Combined with the DIBs measured in GIBS spectra (Paper I), we confirmed a tight relation between EW and E(J −KS) as well as AV, with similar fitting coefficients to those found by previous works. With a more accurate sample and the consideration of the solar motion, the rest-frame wavelength of DIB λ8620 was redetermined as 8620.83 Å, with a mean fit error of 0.36 Å. We studied the kinematics of the DIB carriers by tracing their median radial velocities in each field in the local standard of rest (VLSR) and into the galactocentric frame (VGC), respectively, as a function of the Galactic longitudes. Based on the median VLSR and two Galactic rotation models, we obtained valid kinematic distances of the DIB carriers for nine GIBS and ten GES fields. We also found a linear relation between the DIB λ8620 measured in this work and the near-infrared DIB in APOGEE spectra at 1.5273μm, and we estimated the carrier abundance to be slightly lower compared to the DIB λ15273. Conclusions. We demonstrate that the DIB carriers can be located much closer to the observer than the background stars based on the following arguments: (i) qualitatively, the carriers occupy in the Galactic longitude–velocity diagram typical rotation velocities of stars in the local Galactic disk, while the background stars in the GIBS survey are mainly located in the Galactic bulge; (ii) quantitatively, all the derived kinematic distances of the DIB carriers are smaller than the median distances to background stars in each field. A linear correlation between DIB λ8620 and DIB λ15273 has been established, showing similar carrier abundances and making them both attractive for future studies of the interstellar environments.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"5 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76384997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2021-08-27DOI: 10.1007/s00159-021-00133-8
Francesca Matteucci
In this review, I will discuss the comparison between model results and observational data for the Milky Way, the predictive power of such models as well as their limits. Such a comparison, known as Galactic archaeology, allows us to impose constraints on stellar nucleosynthesis and timescales of formation of the various Galactic components (halo, bulge, thick disk and thin disk).
{"title":"Modelling the chemical evolution of the Milky Way","authors":"Francesca Matteucci","doi":"10.1007/s00159-021-00133-8","DOIUrl":"10.1007/s00159-021-00133-8","url":null,"abstract":"<div><p>In this review, I will discuss the comparison between model results and observational data for the Milky Way, the predictive power of such models as well as their limits. Such a comparison, known as Galactic archaeology, allows us to impose constraints on stellar nucleosynthesis and timescales of formation of the various Galactic components (halo, bulge, thick disk and thin disk).</p></div>","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"29 1","pages":""},"PeriodicalIF":27.8,"publicationDate":"2021-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00159-021-00133-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138514252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-25DOI: 10.1051/0004-6361/202141243
J. Dyks
Radio pulsars exhibit an enormous diversity of single pulse behaviour that involves sudden changes in pulsation mode and nulling occurring on timescales of tens or hundreds of spin periods. The pulsations appear both chaotic and quasi-regular, which has hampered their interpretation for decades. Here I show that the pseudo-chaotic complexity of single pulses is caused by the viewing of a relatively simple radio beam that has a sector structure traceable to the magnetospheric charge distribution. The slow ExB drift of the sector beam, when sampled by the line of sight, produces the classical drift-period-folded patterns known from observations. The drifting azimuthal zones of the beam produce the changes in pulsation modes and both the intermodal and sporadic nulling at timescales of beating between the drift and the star spin. The axially symmetric conal beams are thus a superficial geometric illusion, and the standard carousel model of pulsar radio beams does not apply. The beam suggests a particle flow structure that involves inward motions with possible inward emission.
{"title":"Geometry of radio pulsar signals: The origin of pulsation modes and nulling","authors":"J. Dyks","doi":"10.1051/0004-6361/202141243","DOIUrl":"https://doi.org/10.1051/0004-6361/202141243","url":null,"abstract":"Radio pulsars exhibit an enormous diversity of single pulse behaviour that involves sudden changes in pulsation mode and nulling occurring on timescales of tens or hundreds of spin periods. The pulsations appear both chaotic and quasi-regular, which has hampered their interpretation for decades. Here I show that the pseudo-chaotic complexity of single pulses is caused by the viewing of a relatively simple radio beam that has a sector structure traceable to the magnetospheric charge distribution. The slow ExB drift of the sector beam, when sampled by the line of sight, produces the classical drift-period-folded patterns known from observations. The drifting azimuthal zones of the beam produce the changes in pulsation modes and both the intermodal and sporadic nulling at timescales of beating between the drift and the star spin. The axially symmetric conal beams are thus a superficial geometric illusion, and the standard carousel model of pulsar radio beams does not apply. The beam suggests a particle flow structure that involves inward motions with possible inward emission.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"5 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89629261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2021-08-01DOI: 10.1051/0004-6361/202040028E
R. J. Campbell, M. Mathioudakis, M. Collados, P. Keys, A. Ramos, C. Nelson, D. Kuridze, A. Reid
We correct a typographical error in the original paper. Figures 10, 12, 14, 15, and 16 contain a table in the top right panel with four columns and four rows of values. The line of sight velocity, vLOS, values for scheme 1 inversions (in the fourth row, first column and second column) are inserted the wrong way around. The values themselves are correct, but printed in the wrong column. All other values in the tables remain unaffected, and none of the paper's discussions or conclusions are impacted. We provide corrected versions of Figs. 10, 12, 14, 15, and 16 in Figs. 1, 2, 3, 4, and 5, respectively.
{"title":"Erratum: Temporal evolution of small-scale internetwork magnetic fields in the solar photosphere (A&A (2021) 647 (A182) DOI: 10.1051/0004-6361/202040028)","authors":"R. J. Campbell, M. Mathioudakis, M. Collados, P. Keys, A. Ramos, C. Nelson, D. Kuridze, A. Reid","doi":"10.1051/0004-6361/202040028E","DOIUrl":"https://doi.org/10.1051/0004-6361/202040028E","url":null,"abstract":"We correct a typographical error in the original paper. Figures 10, 12, 14, 15, and 16 contain a table in the top right panel with four columns and four rows of values. The line of sight velocity, vLOS, values for scheme 1 inversions (in the fourth row, first column and second column) are inserted the wrong way around. The values themselves are correct, but printed in the wrong column. All other values in the tables remain unaffected, and none of the paper's discussions or conclusions are impacted. We provide corrected versions of Figs. 10, 12, 14, 15, and 16 in Figs. 1, 2, 3, 4, and 5, respectively.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"57 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73266724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2021-07-21DOI: 10.1051/0004-6361/202141157
M. Bouvier, A. L'opez-Sepulcre, C. Ceccarelli, N. Sakai, S. Yamamoto, Y.-L. Yang
The spectral energy distribution (SED) in the millimetre (mm) to centimetre (cm) range is a useful tool for characterising the dust in protostellar envelopes as well as free-free emission from the protostar and outflow. While many studies have been carried out towards low- and high-mass protostars, little exists so far about solar-type protostars in high-mass star-forming regions, which are likely to be representatives of the conditions where the Solar System was born. We focus here on the OMC-2/3 solar-type protostars, which are bounded by nearby HII regions and which are, therefore, potentially affected by the high-UV illumination. We aim to understand whether the small-scale structure ($leq$1000 au) and the evolutionary status of these solar-type protostars are affected by the nearby HII regions, as is the case for the large-scale ($leq$10$^4$ au) gas chemical composition. We used ALMA in the 1.3 mm band (246.2 GHz) to image the continuum of 16 OMC-2/3 solar-type protostars, with an angular resolution of 0.25$''$ (100 au). We completed our data with archival data from the VANDAM survey of Orion Protostars at 333 and 32.9 GHz, respectively, to construct the dust SED, extract several dust parameters and to assess whether free-free emission is contaminating their dust SED in the cm range. From the mm to cm range dust SED, we found low dust emissivity spectral indexes ($beta < 1$) for the majority of our source sample and free-free emission towards only 5 of the 16 sample sources. We were also able to confirm or correct the evolutionary status of the source sample. Finally, we did not find any dependence of the source dust parameters on their location in the OMC-2/3 filament. Our results show that the small-scale dust properties of the OMC-2/3 protostars are not affected by the high- UV illumination from the nearby HII regions.
{"title":"ORion Alma New GEneration Survey (ORANGES). I. Dust continuum and free-free emission of OMC-2/3 filament protostars","authors":"M. Bouvier, A. L'opez-Sepulcre, C. Ceccarelli, N. Sakai, S. Yamamoto, Y.-L. Yang","doi":"10.1051/0004-6361/202141157","DOIUrl":"https://doi.org/10.1051/0004-6361/202141157","url":null,"abstract":"The spectral energy distribution (SED) in the millimetre (mm) to centimetre (cm) range is a useful tool for characterising the dust in protostellar envelopes as well as free-free emission from the protostar and outflow. While many studies have been carried out towards low- and high-mass protostars, little exists so far about solar-type protostars in high-mass star-forming regions, which are likely to be representatives of the conditions where the Solar System was born. We focus here on the OMC-2/3 solar-type protostars, which are bounded by nearby HII regions and which are, therefore, potentially affected by the high-UV illumination. We aim to understand whether the small-scale structure ($leq$1000 au) and the evolutionary status of these solar-type protostars are affected by the nearby HII regions, as is the case for the large-scale ($leq$10$^4$ au) gas chemical composition. We used ALMA in the 1.3 mm band (246.2 GHz) to image the continuum of 16 OMC-2/3 solar-type protostars, with an angular resolution of 0.25$''$ (100 au). We completed our data with archival data from the VANDAM survey of Orion Protostars at 333 and 32.9 GHz, respectively, to construct the dust SED, extract several dust parameters and to assess whether free-free emission is contaminating their dust SED in the cm range. From the mm to cm range dust SED, we found low dust emissivity spectral indexes ($beta < 1$) for the majority of our source sample and free-free emission towards only 5 of the 16 sample sources. We were also able to confirm or correct the evolutionary status of the source sample. Finally, we did not find any dependence of the source dust parameters on their location in the OMC-2/3 filament. Our results show that the small-scale dust properties of the OMC-2/3 protostars are not affected by the high- UV illumination from the nearby HII regions.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"32 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76017475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2021-07-20DOI: 10.1051/0004-6361/202141591
M. Gelder, B. Tabone, E. Dishoeck, B. Godard
As material from an infalling protostellar envelope hits the forming disk, an accretion shock may develop which could (partially) alter the envelope material entering the disk. Observations with the Atacama Large Millimeter/submillimeter Array (ALMA) indicate that emission originating from warm SO and SO$_2$ might be good tracers of such accretion shocks. The goal of this work is to test under what shock conditions the abundances of gas-phase SO and SO$_2$ increase in an accretion shock at the disk-envelope interface. Detailed shock models including gas dynamics are computed using the Paris-Durham shock code for non-magnetized J-type accretion shocks in typical inner envelope conditions. The effect of pre-shock density, shock velocity, and strength of the ultraviolet (UV) radiation field on the abundance of warm SO and SO$_2$ is explored. Warm gas-phase chemistry is efficient in forming SO under most J-type shock conditions considered. In lower-velocity (~3 km/s) shocks, the abundance of SO is increased through subsequent reactions starting from thermally desorbed CH$_4$ toward H$_2$CO and finally SO. In higher velocity (>4 km/s) shocks, both SO and SO$_2$ are formed through reactions of OH and atomic S. The strength of the UV radiation field is crucial for SO and in particular SO$_2$ formation through the photodissociation of H$_2$O. Thermal desorption of SO and SO$_2$ ice is only relevant in high-velocity (>5 km/s) shocks at high densities ($>10^7$ cm$^{-3}$). Warm emission from SO and SO$_2$ is a possible tracer of accretion shocks at the disk-envelope interface as long as a local UV field is present. Additional observations with ALMA at high-angular resolution could provide further constraints. Moreover, the James Webb Space Telescope will give access to other possible slow, dense shock tracers such as H$_2$, H$_2$O, and [S I] 25$mu$m.
{"title":"Modeling accretion shocks at the disk-envelope interface. Sulfur chemistry","authors":"M. Gelder, B. Tabone, E. Dishoeck, B. Godard","doi":"10.1051/0004-6361/202141591","DOIUrl":"https://doi.org/10.1051/0004-6361/202141591","url":null,"abstract":"As material from an infalling protostellar envelope hits the forming disk, an accretion shock may develop which could (partially) alter the envelope material entering the disk. Observations with the Atacama Large Millimeter/submillimeter Array (ALMA) indicate that emission originating from warm SO and SO$_2$ might be good tracers of such accretion shocks. The goal of this work is to test under what shock conditions the abundances of gas-phase SO and SO$_2$ increase in an accretion shock at the disk-envelope interface. Detailed shock models including gas dynamics are computed using the Paris-Durham shock code for non-magnetized J-type accretion shocks in typical inner envelope conditions. The effect of pre-shock density, shock velocity, and strength of the ultraviolet (UV) radiation field on the abundance of warm SO and SO$_2$ is explored. Warm gas-phase chemistry is efficient in forming SO under most J-type shock conditions considered. In lower-velocity (~3 km/s) shocks, the abundance of SO is increased through subsequent reactions starting from thermally desorbed CH$_4$ toward H$_2$CO and finally SO. In higher velocity (>4 km/s) shocks, both SO and SO$_2$ are formed through reactions of OH and atomic S. The strength of the UV radiation field is crucial for SO and in particular SO$_2$ formation through the photodissociation of H$_2$O. Thermal desorption of SO and SO$_2$ ice is only relevant in high-velocity (>5 km/s) shocks at high densities ($>10^7$ cm$^{-3}$). Warm emission from SO and SO$_2$ is a possible tracer of accretion shocks at the disk-envelope interface as long as a local UV field is present. Additional observations with ALMA at high-angular resolution could provide further constraints. Moreover, the James Webb Space Telescope will give access to other possible slow, dense shock tracers such as H$_2$, H$_2$O, and [S I] 25$mu$m.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"99 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90845480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2021-07-16DOI: 10.1051/0004-6361/202141317
M. Farnir, C. Pinçon, M. Dupret, A. Noels, R. Scuflaire
This study is the first of a series of papers that provide a technique to analyse the mixed-modes frequency spectra and characterise the structure of stars on the subgiant and red-giant branches. We define seismic indicators, relevant of the stellar structure and study their evolution on a grid of models. The proposed method, EGGMiMoSA, relies on the asymptotic description of mixed modes, defines initial guesses for the parameters, and uses a Levenberg-Marquardt technique to adjust the mixed-modes pattern efficiently. We follow the evolution of the mixed-modes parameters along a grid of models from the subgiant phase to the RGB bump and extend past works. We show the impact of the mass and composition on their evolution. The evolution of the period spacing $Deltapi_1$, pressure offset $epsilon_p$, gravity offset $epsilon_g$, and coupling factor $q$ as a function of $Deltanu$ is little affected by the chemical composition and it follows two different regimes depending on the evolutionary stage. On the subgiant branch, the models display a moderate core-envelope density contrast. The evolution of $Delta pi_1$, $epsilon_p$, $epsilon_g$, and $q$ thus significantly changes with the mass. Also, we demonstrate that, at fixed Z/X and with proper measurements of $Deltapi_1$ and $Deltanu$, we may unambiguously constrain the mass, radius and age of a subgiant star. Conversely, on the red-giant branch, the core-envelope density contrast becomes very large. Consequently, the evolution of $epsilon_p$, $epsilon_g$ and $q$ as a function of $Deltanu$ becomes independent of the mass. This is also true for $Delta pi_1$ in stars with masses $lesssim 1.8M_odot$ because of core electron degeneracy. This degeneracy is lifted for higher masses, again allowing for a precise measurement of the age. Overall, our computations qualitatively agree with past observed and theoretical studies.
{"title":"Asteroseismology of evolved stars with EGGMiMoSA. I. Theoretical mixed-mode patterns from the subgiant to the RGB phase","authors":"M. Farnir, C. Pinçon, M. Dupret, A. Noels, R. Scuflaire","doi":"10.1051/0004-6361/202141317","DOIUrl":"https://doi.org/10.1051/0004-6361/202141317","url":null,"abstract":"This study is the first of a series of papers that provide a technique to analyse the mixed-modes frequency spectra and characterise the structure of stars on the subgiant and red-giant branches. We define seismic indicators, relevant of the stellar structure and study their evolution on a grid of models. The proposed method, EGGMiMoSA, relies on the asymptotic description of mixed modes, defines initial guesses for the parameters, and uses a Levenberg-Marquardt technique to adjust the mixed-modes pattern efficiently. We follow the evolution of the mixed-modes parameters along a grid of models from the subgiant phase to the RGB bump and extend past works. We show the impact of the mass and composition on their evolution. The evolution of the period spacing $Deltapi_1$, pressure offset $epsilon_p$, gravity offset $epsilon_g$, and coupling factor $q$ as a function of $Deltanu$ is little affected by the chemical composition and it follows two different regimes depending on the evolutionary stage. On the subgiant branch, the models display a moderate core-envelope density contrast. The evolution of $Delta pi_1$, $epsilon_p$, $epsilon_g$, and $q$ thus significantly changes with the mass. Also, we demonstrate that, at fixed Z/X and with proper measurements of $Deltapi_1$ and $Deltanu$, we may unambiguously constrain the mass, radius and age of a subgiant star. Conversely, on the red-giant branch, the core-envelope density contrast becomes very large. Consequently, the evolution of $epsilon_p$, $epsilon_g$ and $q$ as a function of $Deltanu$ becomes independent of the mass. This is also true for $Delta pi_1$ in stars with masses $lesssim 1.8M_odot$ because of core electron degeneracy. This degeneracy is lifted for higher masses, again allowing for a precise measurement of the age. Overall, our computations qualitatively agree with past observed and theoretical studies.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"102 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80527269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2021-07-16DOI: 10.1051/0004-6361/202039369
G. Koenigsberger, E. Moreno, N. Langer
Rotation contributes to internal mixing processes and observed variability in massive stars. A significant number of binary stars are not in strict synchronous rotation, including all eccentric systems. This leads to a tidally induced and time-variable differential rotation structure. We present a method for exploring the rotation structure of asynchronously rotating binaries. We solve the equations of motion of a 3D grid of volume elements located above the rigidly rotating core in the presence of gravitational, centrifugal, Coriolis, gas pressure and viscous forces to obtain the angular velocity as a function of the three spatial coordinates and time. We find that the induced rotation structure and its temporal variability depend on the degree of departure from synchronicity. In eccentric systems, the structure changes over the orbital cycle with maximum amplitudes occurring potentially at orbital phases other than periastron passage. We discuss the possible role of the time-dependent tidal flows in enhancing the mixing efficiency and speculate that, in this context, slowly rotating asynchronous binaries could have more efficient mixing than the analogous more rapidly rotating but tidally locked systems. We find that some observed nitrogen abundances depend on the orbital inclination, which, if real, would imply an inhomogeneous chemical distribution over the stellar surface or that tidally induced spectral line variability, which is strongest near the equator, affects the abundance determinations. Our models predict that, neglecting other angular momentum transfer mechanisms, a pronounced initial differential rotation structure converges toward average uniform rotation on the viscous timescale. We suggest that by taking into account the processes that are triggered by asynchronous rotation, a broader perspective of binary star structure, evolution and variability may be gleaned.
{"title":"Induced differential rotation and mixing in asynchronous binary stars","authors":"G. Koenigsberger, E. Moreno, N. Langer","doi":"10.1051/0004-6361/202039369","DOIUrl":"https://doi.org/10.1051/0004-6361/202039369","url":null,"abstract":"Rotation contributes to internal mixing processes and observed variability in massive stars. A significant number of binary stars are not in strict synchronous rotation, including all eccentric systems. This leads to a tidally induced and time-variable differential rotation structure. We present a method for exploring the rotation structure of asynchronously rotating binaries. We solve the equations of motion of a 3D grid of volume elements located above the rigidly rotating core in the presence of gravitational, centrifugal, Coriolis, gas pressure and viscous forces to obtain the angular velocity as a function of the three spatial coordinates and time. We find that the induced rotation structure and its temporal variability depend on the degree of departure from synchronicity. In eccentric systems, the structure changes over the orbital cycle with maximum amplitudes occurring potentially at orbital phases other than periastron passage. We discuss the possible role of the time-dependent tidal flows in enhancing the mixing efficiency and speculate that, in this context, slowly rotating asynchronous binaries could have more efficient mixing than the analogous more rapidly rotating but tidally locked systems. We find that some observed nitrogen abundances depend on the orbital inclination, which, if real, would imply an inhomogeneous chemical distribution over the stellar surface or that tidally induced spectral line variability, which is strongest near the equator, affects the abundance determinations. Our models predict that, neglecting other angular momentum transfer mechanisms, a pronounced initial differential rotation structure converges toward average uniform rotation on the viscous timescale. We suggest that by taking into account the processes that are triggered by asynchronous rotation, a broader perspective of binary star structure, evolution and variability may be gleaned.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"31 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73681475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2021-07-14DOI: 10.1051/0004-6361/202140657
A. Kolodzig, N. Aghanim, M. Douspis, E. Pointecouteau, Edouard Lecoq
We conducted an X-ray analysis of one of the two Planck-detected triplet-cluster systems, PLCK G334.8-38.0, with a $sim100$~ks deep XMM-Newton data. We find that the system has a redshift of $z=0.37pm{0.01}$ but the precision of the X-ray spectroscopy for two members is too low to rule out a projected triplet system, demanding optical spectroscopy for further investigation. In projection, the system looks almost like an equilateral triangle with an edge length of $sim2.0,mathrm{Mpc}$, but masses are very unevenly distributed ($M_{500} sim [2.5,0.7,0.3] times 10^{14},mathrm{M_{odot}}$ from bright to faint). The brightest member appears to be a relaxed cool-core cluster and is more than twice as massive as both other members combined. The second brightest member appears to be a disturbed non-cool-core cluster and the third member was too faint to make any classification. None of the clusters have an overlapping $R_{500}$ region and no signs of cluster interaction were found; however, the XMM-Newton data alone are probably not sensitive enough to detect such signs, and a joint analysis of X-ray and the thermal Sunyaev-Zeldovich effect (tSZ) is needed for further investigation, which may also reveal the presence of the warm-hot intergalactic medium (WHIM) within the system. The comparison with the other Planck-detected triplet-cluster-system (PLCK G214.6+36.9) shows that they have rather different configurations, suggesting rather different merger scenarios, under the assumption that they are both not simply projected triplet systems.
我们利用$sim100$ ks深度的XMM-Newton数据对两个普朗克探测到的三重星团系统之一PLCK G334.8-38.0进行了x射线分析。我们发现该系统的红移为$z=0.37pm{0.01}$，但其中两个成员的x射线光谱精度太低，无法排除投影三重态系统，需要进一步的光学光谱研究。在投影中，该系统看起来几乎像一个边长为$sim2.0,mathrm{Mpc}$的等边三角形，但质量分布非常不均匀($M_{500} sim [2.5,0.7,0.3] times 10^{14},mathrm{M_{odot}}$从亮到暗)。最亮的成员似乎是一个松弛的冷核星团，其质量是其他两个成员质量总和的两倍多。第二个最亮的成员似乎是一个不受干扰的非冷核星团，第三个成员太暗而无法进行任何分类。没有一个星团有重叠的$R_{500}$区域，也没有发现星团相互作用的迹象;然而，单靠xmm -牛顿望远镜的数据可能不够灵敏，无法探测到这些迹象，进一步的研究需要对x射线和热Sunyaev-Zeldovich效应(tSZ)进行联合分析，这也可能揭示系统内温热星系际介质(WHIM)的存在。与普朗克探测到的其他三重星团系统(PLCK G214.6+36.9)的比较表明，在假设它们都不是简单的投影三重星团系统的情况下，它们具有相当不同的结构，表明相当不同的合并场景。
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Pub Date : 2021-07-14DOI: 10.1051/0004-6361/202141151
C. Moutou, J. Almenara, G. H'ebrard, N. Santos, K. Stassun, S. Deheuvels, S. Barros, P. Benni, A. Bieryla, I. Boisse, X. Bonfils, P. Boyd, K. Collins, D. Baker, P. Cort'es-Zuleta, S. Dalal, F. Debras, M. Deleuil, X. Delfosse, O. Demangeon, Z. Essack, T. Forveille, E. Girardin, P. Guerra, N. Heidari, K. Hesse, S. Hoyer, J. Jenkins, F. Kiefer, P. Konig, D. Laloum, D. Latham, T. Lopez, E. Martioli, H. Osborn, G. Ricker, S. Seager, R. Vanderspek, M. Vezie, J. Villaseñor, J. Winn, B. Wohler, C. Ziegler
We present the discovery of two new transiting extrasolar planet candidates identified as TOI-1296.01 and TOI-1298.01 by the Transiting Exoplanet Survey Satellite (TESS). The planetary nature of these candidates has been secured with the SOPHIE high-precision spectrograph through the measurement of the companion’s mass with the radial velocity method. Both planets are similar to Saturn in mass and have similar orbital periods of a few days. They, however, show discrepant radii and therefore different densities. The radius discrepancy might be explained by the different levels of irradiation by the host stars. The subgiant star TOI-1296 hosts a low-density planet with 1.2 RJup while the less luminous, lower-size star TOI-1298 hosts a much denser planet with a 0.84 RJup radius, resulting in bulk densities of 0.198 and 0.743 g.cm−3, respectively. In addition, both stars are strongly enriched in heavy elements, having metallicities of +0.44 and +0.49 dex, respectively. The planet masses and orbital periods are 0.298± 0.039 MJup and 3.9443715± 5.8 10−6 days for TOI-1296b, and 0.356± 0.032 MJup and 4.537164± 1.2 10−5 days for TOI-1298b. The mass measurements have a relative precision of better than 13%.
{"title":"TOI-1296b and TOI-1298b observed with TESS and SOPHIE: Two hot Saturn-mass exoplanets with different densities around metal-rich stars","authors":"C. Moutou, J. Almenara, G. H'ebrard, N. Santos, K. Stassun, S. Deheuvels, S. Barros, P. Benni, A. Bieryla, I. Boisse, X. Bonfils, P. Boyd, K. Collins, D. Baker, P. Cort'es-Zuleta, S. Dalal, F. Debras, M. Deleuil, X. Delfosse, O. Demangeon, Z. Essack, T. Forveille, E. Girardin, P. Guerra, N. Heidari, K. Hesse, S. Hoyer, J. Jenkins, F. Kiefer, P. Konig, D. Laloum, D. Latham, T. Lopez, E. Martioli, H. Osborn, G. Ricker, S. Seager, R. Vanderspek, M. Vezie, J. Villaseñor, J. Winn, B. Wohler, C. Ziegler","doi":"10.1051/0004-6361/202141151","DOIUrl":"https://doi.org/10.1051/0004-6361/202141151","url":null,"abstract":"We present the discovery of two new transiting extrasolar planet candidates identified as TOI-1296.01 and TOI-1298.01 by the Transiting Exoplanet Survey Satellite (TESS). The planetary nature of these candidates has been secured with the SOPHIE high-precision spectrograph through the measurement of the companion’s mass with the radial velocity method. Both planets are similar to Saturn in mass and have similar orbital periods of a few days. They, however, show discrepant radii and therefore different densities. The radius discrepancy might be explained by the different levels of irradiation by the host stars. The subgiant star TOI-1296 hosts a low-density planet with 1.2 RJup while the less luminous, lower-size star TOI-1298 hosts a much denser planet with a 0.84 RJup radius, resulting in bulk densities of 0.198 and 0.743 g.cm−3, respectively. In addition, both stars are strongly enriched in heavy elements, having metallicities of +0.44 and +0.49 dex, respectively. The planet masses and orbital periods are 0.298± 0.039 MJup and 3.9443715± 5.8 10−6 days for TOI-1296b, and 0.356± 0.032 MJup and 4.537164± 1.2 10−5 days for TOI-1298b. The mass measurements have a relative precision of better than 13%.","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"3 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2021-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86626840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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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