- ID:
- ivo://CDS.VizieR/J/MNRAS/435/2161
- Title:
- Catalogue of bright (K<9) M dwarfs
- Short Name:
- J/MNRAS/435/2161
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the Position and Proper Motion Extended-L (PPMXL) catalogue, we have used optical and near-infrared colour cuts together with a reduced proper motion cut to find bright M dwarfs for future exoplanet transit studies. PPMXL's low proper motion uncertainties allow us to probe down to smaller proper motions than previous similar studies. We have combined unique objects found with this method to that of previous work to produce 8479 K<9 M dwarfs. Low-resolution spectroscopy was obtained of a sample of the objects found using this selection method to gain statistics on their spectral type and physical properties. Results show a spectral-type range of K7-M4V. This catalogue is the most complete collection of K<9 M dwarfs currently available and is made available here.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/326/249
- Title:
- Chromospheric models of dwarf M stars
- Short Name:
- J/A+A/326/249
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Tables 4 and 5 give the atmospheric parameters for our models of dM stars Gl 588 and Gl 628. The columns give the column mass in g/cm^-2^, the electron temperature in K, the microturbulent velocity in km/s; the continuum optical depth at 5000{AA}; the hydrogen, proton, and electron density in particles per cm^-3^; and the height h (in km) above the level where tau_5000_=1.
- ID:
- ivo://CDS.VizieR/J/AJ/131/1674
- Title:
- Close binary systems from SDSS DR4
- Short Name:
- J/AJ/131/1674
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic sample of 746 detached close binary systems from the Sloan Digital Sky Survey (SDSS) Fourth Data Release (2006ApJS..162...38A). The majority of these binaries consist of a white dwarf primary and a low-mass secondary (typically M dwarf) companion. We have determined the temperature and gravity for 496 of the white dwarf primaries and the spectral type and magnetic activity properties for 661 of the low-mass secondaries. We have estimated the distances for each of the white dwarf-main-sequence star binaries and use white dwarf evolutionary grids to establish the age of each binary system from the white dwarf cooling times.
- ID:
- ivo://CDS.VizieR/J/AJ/153/165
- Title:
- Collisions of terrestrial worlds
- Short Name:
- J/AJ/153/165
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an investigation into the occurrence and properties (stellar age and mass trends) of low- mass field stars exhibiting extreme mid-infrared (MIR) excesses (LIR/L*~>~0.01). Stars for the analysis were initially selected from the Motion Verified Red Stars (MoVeRS) catalog of photometric stars with Sloan Digital Sky Survey, 2MASS, and WISE photometry and significant proper motions. We identify 584 stars exhibiting extreme MIR excesses, selected based on an empirical relationship for main-sequence W1-W3 colors. For a small subset of the sample, we show, using spectroscopic tracers of stellar age (H{alpha} and LiI) and luminosity class, that the parent sample is most likely comprised of field dwarfs (>1Gyr). We also develop the Low-mass Kinematics (LoKi) galactic model to estimate the completeness of the extreme MIR excess sample. Using Galactic height as a proxy for stellar age, the completeness-corrected analysis indicates a distinct age dependence for field stars exhibiting extreme MIR excesses. We also find a trend with stellar mass (using r-z color as a proxy). Our findings are consistent with the detected extreme MIR excesses originating from dust created in a short-lived collisional cascade (<100000-years) during a giant impact between two large planetismals or terrestrial planets. These stars with extreme MIR excesses also provide support for planetary collisions being the dominant mechanism in creating the observed Kepler dichotomy (the need for more than a single mode, typically two, to explain the variety of planetary system architectures Kepler has observed), rather than different formation mechanisms.
- ID:
- ivo://CDS.VizieR/J/AJ/119/1424
- Title:
- Color-temperature relations of M giants
- Short Name:
- J/AJ/119/1424
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of a project to model the integrated spectra and colors of elliptical galaxies through evolutionary synthesis, we have refined our synthetic spectrum calculations of M giants. After critically assessing three effective temperature scales for M giants, we adopted the relation of Dyck et al. for our models. Using empirical spectra of field M giants as a guide, we then calculated MARCS stellar atmosphere models (Gustafsson et al. 1975; Bell et al. 1976) and SSG synthetic spectra (Bell & Gustafsson 1978; Gustafsson & Bell 1979) of these cool stars, adjusting the band absorption oscillator strengths of the TiO bands to better reproduce the observational data. The resulting synthetic spectra are found to be in very good agreement with the K-band spectra of stars of the appropriate spectral type taken from Kleinmann & Hall (1986) as well. Spectral types estimated from the strengths of the TiO bands and the depth of the band head of CO near 2.3 {mu}m quantitatively confirm that the synthetic spectra are good representations of those of field M giants. The broadband colors of the models match the field relations of K and early-M giants very well; for late-M giants, differences between the field star and synthetic colors are probably caused by the omission of spectral lines of VO and H_2_O in the spectrum synthesis calculations. Here, we present four grids of K-band bolometric corrections and colors - Johnson U-V and B-V, Cousins V-R and V-I, Johnson-Glass V-K, J-K, and H-K, and CIT/CTIO V-K, J-K, H-K, and CO - for models having 3000 K {<=} Teff {<=} 4000 K and -0.5 {<=} log(g) {<=} 1.5.
- ID:
- ivo://CDS.VizieR/J/A+A/325/159
- Title:
- Companions to M dwarfs within 5pc
- Short Name:
- J/A+A/325/159
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The paper contains four tables which summarise the duplicity status of the 34 M dwarf primaries within 5.0pc. Table 1 gives the basic data for the sample: designation, coordinates, V,J,H,K photometry, parallax Table 2 gives, for the nine southern sources, magnitude limits for possible undetected companions. These limits are given for assumed projected separations of 1AU, 2AU, 5AU, and 10AU. In addition, the circumstances of the observation are given: date, telescope, and observational technique. Table 3 repeats, in updated form, the same information (except for the date) for the 25 northern sources. Table 4 lists the nine M dwarf primaries within 5pc which do have one or more companions.
- ID:
- ivo://CDS.VizieR/J/ApJ/887/261
- Title:
- Compilation of planets around M dwarfs
- Short Name:
- J/ApJ/887/261
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- M dwarfs host most of the exoplanets in the local Milky Way. Some of these planets, ranging from sub-Earths to super-Jupiters, orbit in their stars' habitable zones (HZs), although many likely possess surface environments that preclude habitability. Moreover, exomoons around these planets could harbor life for long timescales and thus may also be targets for biosignature surveys. Here we investigate the potential habitability, stability, and detectability of exomoons around exoplanets orbiting M dwarfs. We first compile an updated list of known M-dwarf exoplanet hosts, comprising 109 stars and 205 planets. For each M dwarf, we compute and update precise luminosities with the Virtual Observatory spectral energy distribution Analyzer and Gaia DR2 parallaxes to determine inner and outer boundaries of their HZs. For each planet, we retrieve (or, when necessary, homogeneously estimate) their masses and radii, calculate the long-term dynamical stability of hypothetical moons, and identify those planets that can support habitable moons. We find that 33 exoplanet candidates are located in the HZs of their host stars and that four of them could host Moon- to Titan-mass exomoons for timescales longer than the Hubble time.
- ID:
- ivo://CDS.VizieR/J/A+A/629/A83
- Title:
- Complexity of magnetic fields on red dwarfs
- Short Name:
- J/A+A/629/A83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Generation, amplification, and evolution of magnetic fields in cool stars can be investigated by measuring the Zeeman effect in atomic and molecular lines observed in their spectra. In particular, Zeeman line broadening and polarization have been used for detecting magnetic fields in stellar atmospheres. Similar to the Sun, these fields are complex and height-dependent (i.e., comprise 3D structures) and require advanced diagnostics. Fortunately, many molecular lines dominating M-dwarf spectra, such as FeH, CaH, MgH, and TiO, are temperature- and Zeeman- sensitive and form at different atmospheric heights, which makes them excellent probes of magnetic fields on M dwarfs. Our goal is to analyze the complexity of magnetic fields in M dwarfs. We investigate how magnetic fields vary with the stellar temperature (i.e., mass) and how "surface" inhomogeneities are distributed in height - the dimension that is usually neglected in stellar magnetic studies. This is achieved by including many atomic and molecular species in our study. We have determined effective temperatures of the photosphere and of magnetic features, magnetic field strengths and filling factors for nine M dwarfs (M1-M7). Our chi^2^ analysis is based on a comparison of observed and synthetic intensity and circular polarization profiles (Stokes I and V) of many magnetically sensitive atomic and molecular lines in ten wavelength regions. Stokes profiles were calculated by solving polarized radiative transfer equations under the local thermodynamic equilibrium using model atmospheres. We have found that properties of magnetic structures depend on the analyzed atomic or molecular species and their formation heights within the atmosphere. Two types of magnetic features similar to those on the Sun have been found: one is cooler (starspots), while the other one is hotter (network, small-scale magnetic features). The magnetic field strength in both starspots and network is within 3kG to 6kG, on average it is 5kG for the M1-M7 spectral class range. These fields occupy a large fraction of M dwarf atmospheres at all heights, up to 100%. The plasma beta is less than one throughout the entire M dwarf atmospheres, implying that they are highly magnetized stars. A combination of many molecular and atomic species and a simultaneous analysis of intensity and circular polarization spectra have allowed us to better decipher the complexity of magnetic fields on M dwarfs, including their dependence on the height within the atmosphere. This work provides an opportunity to investigate a larger sample of M dwarfs as well as L-type brown dwarfs.
- ID:
- ivo://CDS.VizieR/J/MNRAS/443/2561
- Title:
- CONCH-SHELL catalog of nearby M dwarfs
- Short Name:
- J/MNRAS/443/2561
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an all-sky catalogue of 2970 nearby (d<~50pc), bright (J<9) M- or late K-type dwarf stars, 86% of which have been confirmed by spectroscopy. This catalogue will be useful for searches for Earth-size and possibly Earth-like planets by future space-based transit missions and ground-based infrared Doppler radial velocity surveys. Stars were selected from the SUPERBLINK proper motion catalogue (Cat. I/298) according to absolute magnitudes, spectra, or a combination of reduced proper motions and photometric colours. From our spectra, we determined gravity-sensitive indices, and identified and removed 0.2% of these as interloping hotter or evolved stars. 13% of the stars exhibit H{alpha} emission, an indication of stellar magnetic activity and possible youth. The mean metallicity is [Fe/H]=-0.07 with a standard deviation of 0.22dex, similar to nearby solar-type stars. We determined stellar effective temperatures by least-squares fitting of spectra to model predictions calibrated by fits to stars with established bolometric temperatures, and estimated radii, luminosities, and masses using empirical relations. 6% of stars with images from integral field spectra are resolved doubles. We inferred the planet population around M dwarfs using Kepler data and applied this to our catalogue to predict detections by future exoplanet surveys.
- ID:
- ivo://CDS.VizieR/J/AJ/154/142
- Title:
- Corrected photometry for GJ 1132 for all eclipses
- Short Name:
- J/AJ/154/142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for additional bodies in the GJ 1132 system through two methods: photometric transits and transit timing variations of GJ 1132b. We collected 21 transit observations of GJ 1132b with the MEarth-South array. We obtained 100 near-continuous hours of observations with the Spitzer Space Telescope, including two transits of GJ 1132b and spanning 60% of the orbital phase of the maximum (6.9-day) period at which bodies coplanar with GJ 1132b would transit. We exclude transits of additional Mars-sized bodies, such as a second planet or a moon, with a confidence of 99.7%. We find that the planet-to-star radius ratio inferred from the MEarth and Spitzer light curves are discrepant at the 3.7{sigma} level, which we ascribe to the effects of starspots and faculae. When we combine the mass estimate of the star (obtained from its parallax and apparent K_s_ band magnitude) with the stellar density inferred from our high-cadence Spitzer light curve (assuming zero eccentricity), we measure the stellar radius of GJ 1132 to be 0.2105_-0.0085_^+0.0102^ R_{sun}_, and we refine the radius measurement of GJ 1132b to 1.130+/-0.056 R_{Earth}_. Combined with HARPS RV measurements, we determine the density of GJ 1132b to be 6.2+/-2.0 g/cm^3^. We refine the ephemeris of the system (improving the period determination by an order of magnitude) and find no evidence for transit timing variations, which would be expected if there was a second planet near an orbital resonance with GJ 1132b.
