- 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.
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Search Results
- 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/MNRAS/484/5049
- Title:
- DECam Survey of Scorpius Centaurus
- Short Name:
- J/MNRAS/484/5049
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using images taken with the Dark Energy Camera (DECam), the first extensive survey of low mass and substellar objects is made in the ~15-20Myr Upper Centaurus Lupus (UCL) and Lower Centaurus Crux (LCC) subgroups of the Scorpius-Centaurus OB Association (Sco-Cen). Due to the size of our data set (>2Tb), we developed an extensive open source set of python libraries to reduce our images, including astrometry, coaddition, and PSF photometry. Our survey consists of 29x3deg^2^ fields in the UCL and LCC subgroups of Sco-Cen and the creation of a catalogue with over 11 million point sources. We create a prioritized list of UCL and LCC candidate members, with 118 best and another 348 good candidates. We show that the luminosity and mass functions of our low mass and substellar candidates are consistent with measurements for the younger Upper Scorpius subgroup and estimates of a universal IMF, with spectral types ranging from M1 down to L1.
- ID:
- ivo://CDS.VizieR/J/A+A/401/959
- Title:
- 35 DENIS late-M dwarfs between 10 and 30pc
- Short Name:
- J/A+A/401/959
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper reports updated results on our systematic mining of the DENIS database (<B/denis>) for nearby very cool M-dwarfs (M6V-M8V, 2.0=<I-J=<3.0, photometric distance within 30pc), initiated by Phan-Bao et al. (2001, Cat. <J/A+A/380/590>, hereafter Paper I). We use M dwarfs with well measured parallaxes (HIP, GCTP,...) to calibrate the DENIS (M_I_, I-J) colour-luminosity relationship. The resulting distance error for single dwarfs is about 25%. Proper motions, as well as B and R magnitudes, were measured on archive Schmidt plates for those stars in the DENIS database that meet the photometric selection criteria. We then eliminate the giants by a Reduced Proper Motion cutoff, which is significantly more selective than a simple proper motion cutoff. It greatly reduces the selection bias against low tangential velocity stars, and results in a nearly complete sample. Here we present new data for 62 red dwarf candidates selected over 5700 square degrees in the DENIS database. 26 of those originate in the 2100 square degrees analysed in Paper I, with improved parameters here, and 36 were found in 3600 additional square degrees. 25 of those are new nearby dwarfs. In addition we cross-identified the NLTT and DENIS catalogues to find 15 similar stars, in parts of the sky not yet covered by the colour-selected search. We present distance and luminosity estimates for these 15 stars, 10 of which are newly recognized nearby dwarfs. A similar search in Paper I produced 4 red dwarf candidates, and we have thus up to now identified a total of 35 new nearby late-M dwarfs.
- ID:
- ivo://CDS.VizieR/J/A+A/380/590
- Title:
- 30 DENIS late-M dwarfs between 15 and 30pc
- Short Name:
- J/A+A/380/590
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 30 new nearby (d<30pc) red dwarf candidates, with estimated spectral types M6 to M8. 26 were directly selected from the DENIS database (<B/denis>), and another 4 were first extracted from the LHS catalogue (<I/87>) and cross-identified with a DENIS counterpart. Their proper motions were measured on the MAMA measuring machine from plates spanning 13 to 48 years, and are larger than 0.1arcsec/yr, ruling out the possibility that they are giants. Their distances were estimated from the DENIS colours and IR colour-magnitude relations and range between 15 and 30pc.
- ID:
- ivo://CDS.VizieR/J/MNRAS/489/5301
- Title:
- DES Y3 substellar LT and M catalogs
- Short Name:
- J/MNRAS/489/5301
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we present a catalogue of 11745 brown dwarfs with spectral types ranging from L0 to T9, photometrically classified using data from the Dark Energy Survey (DES) year 3 release matched to the Vista Hemisphere Survey (VHS) DR3 and Wide-field Infrared Survey Explorer (WISE) data, covering ~2400deg^2^ up to i_AB_=22. The classification method follows the same photo-type method previously applied to SDSS-UKIDSS-WISE data. The most significant difference comes from the use of DES data instead of SDSS, which allow us to classify almost an order of magnitude more brown dwarfs than any previous search and reaching distances beyond 400 parsecs for the earliest types. Next, we also present and validate the GalmodBD simulation, which produces brown dwarf number counts as a function of structural parameters with realistic photometric properties of a given survey. We use this simulation to estimate the completeness and purity of our photometric LT catalogue down to i_AB_=22, as well as to compare to the observed number of LT types. We put constraints on the thin disk scale height for the early L (L0-L3) population to be around 450 parsecs, in agreement with previous findings. For completeness, we also publish in a separate table a catalogue of 20863 M dwarfs that passed our colour cut with spectral types greater than M6. Both the LT and the late M catalogues are found at https://des.ncsa.illinois.edu/releases/other/y3-mlt.
- ID:
- ivo://CDS.VizieR/J/MNRAS/426/1507
- Title:
- Detached M dwarf eclipsing binaries in WTS
- Short Name:
- J/MNRAS/426/1507
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of 16 detached M dwarf eclipsing binaries (MEBs) with J<16mag and provide a detailed characterization of three of them, using high-precision infrared light curves from the WFCAM Transit Survey (WTS). Such systems provide the most accurate and model-independent method for measuring the fundamental parameters of these poorly understood yet numerous stars, which currently lack sufficient observations to precisely calibrate stellar evolution models.
- ID:
- ivo://CDS.VizieR/J/ApJ/788/114
- Title:
- Detection of Kepler multiple M-star systems
- Short Name:
- J/ApJ/788/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have searched the Kepler light curves of ~3900 M-star targets for evidence of periodicities that indicate, by means of the effects of starspots, rapid stellar rotation. Several analysis techniques, including Fourier transforms, inspection of folded light curves, "sonograms", and phase tracking of individual modulation cycles, were applied in order to distinguish the periodicities due to rapid rotation from those due to stellar pulsations, eclipsing binaries, or transiting planets. We find 178 Kepler M-star targets with rotation periods, P_rot_<2 days, and 110 with P_rot_<1 day. Some 30 of the 178 systems exhibit two or more independent short periods within the same Kepler photometric aperture, while several have 3 or more short periods. Adaptive optics imaging and modeling of the Kepler pixel response function for a subset of our sample support the conclusion that the targets with multiple periods are highly likely to be relatively young physical binary, triple, and even quadruple M star systems. We explore in detail the one object with four incommensurate periods all less than 1.2 days, and show that two of the periods arise from one of a close pair of stars, while the other two arise from the second star, which itself is probably a visual binary. If most of these M-star systems with multiple periods turn out to be bound M-stars, this could prove a valuable way discovering young hierarchical M-star systems; the same approach may also be applicable to G and K stars. The ~5% occurrence rate of rapid rotation among the ~3900 M star targets is consistent with spin evolution models that include an initial contraction phase followed by magnetic braking, wherein a typical M star can spend several hundred Myr before spinning down to periods longer than 2 days.
