- ID:
- ivo://CDS.VizieR/J/A+A/638/A76
- Title:
- StarHorse data for 5 surveys
- Short Name:
- J/A+A/638/A76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combine high-resolution spectroscopic data from APOGEE-2 survey Data Release 16 (DR16) with broad-band photometric data from several sources, as well as parallaxes from Gaia Data Release 2 (DR2). Using the Bayesian isochrone-fitting code StarHorse, we derive distances, extinctions and astrophysical parameters for around 388,815 APOGEE stars, achieving typical distance uncertainties of 6% for APOGEE giants, 2% for APOGEE dwarfs, as well as extinction uncertainties of 0.07mag when all photometric information is available, and 0.17mag if optical photometry is missing. StarHorse uncertainties vary with the input spectroscopic catalogue, with the available photometry, and with the parallax uncertainties. To illustrate the impact of our results, we show that, thanks to Gaia DR2 and the now larger sky coverage of APOGEE-2 (including APOGEE-South), we obtain an extended map of the Galactic plane, providing an unprecedented coverage of the disk close to the Galactic mid-plane (|ZGal|<1kpc) from the Galactic Centre out to RGal 20 kpc. The improvements in statistics as well as distance and extinction uncertainties unveil the presence of the bar in stellar density, as well as the striking chemical duality in the innermost regions of the disk, now clearly extending to the inner bulge. We complement this paper with distances and extinctions for stars in other public released spectroscopic surveys: 324,999 in GALAH DR2, 4,928,715 in LAMOST DR5, 408,894 in RAVE DR6, and 6,095 in GES DR3.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/474/5158
- Title:
- Stars with hot Jupiter exoplanets
- Short Name:
- J/MNRAS/474/5158
- Date:
- 07 Dec 2021 00:40:26
- Publisher:
- CDS
- Description:
- We present a grid of forward model transmission spectra, adopting an isothermal temperature-pressure profile, alongside corresponding equilibrium chemical abundances for 117 observationally significant hot exoplanets (equilibrium temperatures of 547-2710K). This model grid has been developed using a 1D radiative-convective-chemical equilibrium model termed ATMO, with up-to-date high-temperature opacities. We present an interpretation of observations of 10 exoplanets, including best-fitting parameters and {chi}^2^ maps. In agreement with previous works, we find a continuum from clear to hazy/cloudy atmospheres for this sample of hot Jupiters. The data for all the 10 planets are consistent with subsolar to solar C/O ratio, 0.005 to 10 times solar metallicity and water rather than methane-dominated infrared spectra. We then explore the range of simulated atmospheric spectra for different exoplanets, based on characteristics such as temperature, metallicity, C/O ratio, haziness and cloudiness. We find a transition value for the metallicity between 10 and 50 times solar, which leads to substantial changes in the transmission spectra. We also find a transition value of C/O ratio, from water to carbon species dominated infrared spectra, as found by previous works, revealing a temperature dependence of this transition point ranging from ~0.56 to ~1-1.3 for equilibrium temperatures from ~900 to ~2600K. We highlight the potential of the spectral features of HCN and C2H2 to constrain the metallicities and C/O ratios of planets, using James Webb Space Telescope (JWST) observations. Finally, our entire grid (~460000 simulations) is publicly available and can be used directly with the JWST simulator PandExo for planning observations.
- ID:
- ivo://CDS.VizieR/J/AJ/160/214
- Title:
- 130 Stellar ages & planetary orbital properties
- Short Name:
- J/AJ/160/214
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Many exoplanets have orbital characteristics quite different from those seen in our own solar system, including planets locked in orbital resonances and planets on orbits that are elliptical or highly inclined from their host star's spin axis. It is debated whether the wide variety in system architecture is primarily due to differences in formation conditions (nature) or due to evolution over time (nurture). Identifying trends between planetary and stellar properties, including stellar age, can help distinguish between these competing theories and offer insights as to how planets form and evolve. However, it can be challenging to determine whether observed trends between planetary properties and stellar age are driven by the age of the system- pointing to evolution over time being an important factor-or other parameters to which the age may be related, such as stellar mass or stellar temperature. The situation is complicated further by the possibilities of selection biases, small number statistics, uncertainties in stellar age, and orbital evolution timescales that are typically much shorter than the range of observed ages. Here, we develop a Bayesian statistical framework to assess the robustness of such observed correlations and to determine whether they are indeed due to evolutionary processes, are more likely to reflect different formation scenarios, or are merely coincidental. We apply this framework to reported trends between stellar age and 2:1 orbital resonances, spin-orbit misalignments, and hot Jupiters' orbital eccentricities. We find strong support for the nurture hypothesis only in the final case.
- ID:
- ivo://CDS.VizieR/J/ApJ/809/25
- Title:
- Stellar and planet properties for K2 candidates
- Short Name:
- J/ApJ/809/25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The extended Kepler mission, K2, is now providing photometry of new fields every three months in a search for transiting planets. In a recent study, Foreman-Mackey and collaborators presented a list of 36 planet candidates orbiting 31 stars in K2 Campaign 1. In this contribution, we present stellar and planetary properties for all systems. We combine ground-based seeing-limited survey data and adaptive optics imaging with an automated transit analysis scheme to validate 21 candidates as planets, 17 for the first time, and identify 6 candidates as likely false positives. Of particular interest is K2-18 (EPIC 201912552), a bright (K=8.9) M2.8 dwarf hosting a 2.23+/-0.25 R_{earth}_ planet with T_eq_=272+/-15 K and an orbital period of 33 days. We also present two new open-source software packages which enable this analysis. The first, isochrones, is a flexible tool for fitting theoretical stellar models to observational data to determine stellar properties using a nested sampling scheme to capture the multimodal nature of the posterior distributions of the physical parameters of stars that may plausibly be evolved. The second is vespa, a new general-purpose procedure to calculate false positive probabilities and statistically validate transiting exoplanets.
- ID:
- ivo://CDS.VizieR/J/A+A/575/A12
- Title:
- Stellar CharactEristics Pisa Estimation gRid
- Short Name:
- J/A+A/575/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stellar age determination by means of grid-based techniques that adopt asteroseismic constraints is a well established method nowadays. However some theoretical aspects of the systematic and statistical errors affecting these age estimates still have to be investigated. We study the impact on stellar age determination of the uncertainty in the radiative opacity, in the initial helium abundance, in the mixing-length value, in the convective core overshooting, and in the microscopic diffusion efficiency adopted in stellar model computations. We extended our SCEPtER grid to include stars with mass in the range [0.8; 1.6]M_{sun}_ and evolutionary stages from the zero-age main sequence to the central hydrogen depletion. For the age estimation we adopted the same maximum likelihood technique as described in our previous work. To quantify the systematic errors arising from the current uncertainty in model computations, many synthetic grids of stellar models with perturbed input were adopted. We found that the current typical uncertainty in the observations accounts for 1{sigma} statistical relative error in age determination, which on average ranges from about -35% to +42%, depending on the mass. However, owing to the strong dependence on the evolutionary phase, the age's relative error can be higher than 120% for stars near the zero-age main sequence, while it is typically of the order of 20% or lower in the advanced main-sequence phase. The systematic bias on age determination due to a variation of +/-1 in the helium-to-metal enrichment ratio {Delta}Y/{Delta}Z is about one-fourth of the statistical error in the first 30% of the evolution, while it is negligible for more evolved stages. The maximum bias due to the presence of the convective core overshooting is -7% and -13% for mild and strong overshooting scenarios. For all the examined models, the impact of a variation of +/-5% in the radiative opacity was found to be negligible. The most important source of bias is the uncertainty in the mixing-length value {alpha}_ml_ and the neglect of microscopic diffusion. Each of these effects accounts for a bias that is nearly equal to the random error uncertainty. Comparison of the results of our technique with other grid techniques on a set of common stars showed general agreement. However, the adoption of a different grid can account for a variation in the mean estimated age up to 1Gyr.
- ID:
- ivo://CDS.VizieR/J/MNRAS/396/2295
- Title:
- Stellar cluster dynamical masses in NGC2903
- Short Name:
- J/MNRAS/396/2295
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gas and star velocity dispersions have been derived for four circumnuclear star-forming regions (CNSFRs) and the nucleus of the spiral galaxy NGC 2903 using high-resolution spectroscopy in the blue and far red. Stellar velocity dispersions have been obtained from the CaII triplet lines at {lambda}{lambda} 8494, 8542, 8662{AA}, using cross-correlation techniques, while gas velocity dispersions have been measured by Gaussian fits to the H{beta} {lambda} 4861{AA} line.
- ID:
- ivo://CDS.VizieR/J/MNRAS/402/1005
- Title:
- Stellar cluster dynamical masses in NGC3310
- Short Name:
- J/MNRAS/402/1005
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gas and star velocity dispersions have been derived for eight circumnuclear star-forming regions (CNSFRs) and the nucleus of the spiral galaxy NGC 3310 using high-resolution spectroscopy in the blue and far red. Stellar velocity dispersions have been obtained from the CaII triplet in the near-IR, using cross-correlation techniques, while gas velocity dispersions have been measured by Gaussian fits to the H{beta} {lambda}4861{AA} and [OIII] {lambda}5007{AA} emission lines.
- ID:
- ivo://CDS.VizieR/J/AN/341/996
- Title:
- Stellar companions of (C)TOIs
- Short Name:
- J/AN/341/996
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The first results of a new survey are reported, which explores the 2nd data release of the ESA-Gaia mission, in order to search for stellar companions of (Community) TESS Objects of Interest and to characterize their properties. In total, 193 binary and 15 hierarchical triple star systems are presented, detected among 1391 target stars, which are located at distances closer than about 500pc around the Sun. The companions and the targets are equidistant and share a common proper motion, as it is expected for gravitationally bound stellar systems, proven with their accurate Gaia astrometry. The companions exhibit masses in the range between about 0.08M_{sun}_ and 3M_{sun}_ and are most frequently found in the mass range between 0.13 and 0.6M_{sun}_. The companions are separated from the targets by about 40 up to 9900au, and their frequency continually decreases with increasing separation. While most of the detected companions are late K to mid M dwarfs, also 5 white dwarf companions were identified in this survey, whose true nature is revealed by their photometric properties.
- ID:
- ivo://CDS.VizieR/J/AN/342/840
- Title:
- Stellar companions of (C)TOIs
- Short Name:
- J/AN/342/840
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the latest results of our ongoing multiplicity study of (Community) TESS Objects of Interest, using astro- and photometric data from the ESA-Gaia mission, to detect stellar companions of these stars and to characterize their properties. In total, 107 binary, 5 hierarchical triple star systems, as well as one quadruple system were detected among 585 targets surveyed, which are all located at distances closer than about 500pc around the Sun. As proven with their accurate Gaia EDR3 astrometry, the companions and the targets are located at the same distance and share a common proper motion, as it is expected for components of gravitationally bound stellar systems. The companions exhibit masses in the range between about 0.09M_{sun}_ and 4.5M_{sun}_ and are most frequently found in the mass range between 0.15 and 0.6M_{sun}_. The companions are separated from the targets by about 120 up to 9500au and their frequency is the highest and constant within about 500au while it continually decreases for larger separations. Beside mainly early to mid M dwarfs, also 5 white dwarf companions were identified in this survey, whose true nature was revealed by their photometric properties.
- ID:
- ivo://CDS.VizieR/J/ApJ/829/23
- Title:
- Stellar flares from Q0-Q17 Kepler LCs
- Short Name:
- J/ApJ/829/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A homogeneous search for stellar flares has been performed using every available Kepler light curve. An iterative light curve de-trending approach was used to filter out both astrophysical and systematic variability to detect flares. The flare recovery completeness has also been computed throughout each light curve using artificial flare injection tests, and the tools for this work have been made publicly available. The final sample contains 851168 candidate flare events recovered above the 68% completeness threshold, which were detected from 4041 stars, or 1.9% of the stars in the Kepler database. The average flare energy detected is ~10^35^erg. The net fraction of flare stars increases with g-i color, or decreasing stellar mass. For stars in this sample with previously measured rotation periods, the total relative flare luminosity is compared to the Rossby number. A tentative detection of flare activity saturation for low-mass stars with rapid rotation below a Rossby number of ~0.03 is found. A power-law decay in flare activity with Rossby number is found with a slope of -1, shallower than typical measurements for X-ray activity decay with Rossby number.
