- 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.
Number of results to display per page
Search Results
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/771/L45
- Title:
- 3D global climate models for exoplanet around M-star
- Short Name:
- J/ApJ/771/L45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The habitable zone (HZ) is the circumstellar region where a planet can sustain surface liquid water. Searching for terrestrial planets in the HZ of nearby stars is the stated goal of ongoing and planned extrasolar planet surveys. Previous estimates of the inner edge of the HZ were based on one-dimensional radiative-convective models. The most serious limitation of these models is the inability to predict cloud behavior. Here we use global climate models with sophisticated cloud schemes to show that due to a stabilizing cloud feedback, tidally locked planets can be habitable at twice the stellar flux found by previous studies. This dramatically expands the HZ and roughly doubles the frequency of habitable planets orbiting red dwarf stars. At high stellar flux, strong convection produces thick water clouds near the substellar location that greatly increase the planetary albedo and reduce surface temperatures. Higher insolation produces stronger substellar convection and therefore higher albedo, making this phenomenon a stabilizing climate feedback. Substellar clouds also effectively block outgoing radiation from the surface, reducing or even completely reversing the thermal emission contrast between dayside and nightside. The presence of substellar water clouds and the resulting clement surface conditions will therefore be detectable with the James Webb Space Telescope.
- ID:
- ivo://CDS.VizieR/J/A+A/614/A35
- Title:
- Differential photometry of GJ1214
- Short Name:
- J/A+A/614/A35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To investigate the star spots of the M dwarf GJ 1214, we conducted a multi-color photometric monitoring from 2012 to 2016. We measured the rotation period of the host star, measured an increase in variability amplitude, determined the permanent spot filling factor, the spot temperature contrast and persistent longitudes. We determined the effect of the star spots on the planetary transmission spectrum.
- ID:
- ivo://CDS.VizieR/J/MNRAS/451/2263
- Title:
- Differential photometry of the EB* HATS551-027
- Short Name:
- J/MNRAS/451/2263
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery and characterization of a new M-dwarf binary, with component masses and radii of M_1_=0.244_-0.003_^+0.003^M_{sun}_, R_1_=0.261_-0.009_^+0.006^R_{sun}_, M_2_=0.179_-0.001_^+0.002^M_{sun}_, R_2_=0.218_-0.011_^+0.007^R_{sun}_, and orbital period of ~4.1 d. The M-dwarf binary HATS551-027 (LP 837-20) was identified as an eclipsing binary by the HATSouth survey, and characterized by a series of high-precision photometric observations of the eclipse events, and spectroscopic determinations of the atmospheric parameters and radial velocity orbits. HATS551-027 is one of few systems with both stellar components lying in the fully convective regime of very low mass stars, and can serve as a test for stellar interior models. The radius of HATS551-027A is consistent with models to 1{sigma}, whilst HATS551-027B is inflated by 9 percent at 2{sigma} significance. We measure the effective temperatures for the two stellar components to be T_eff,1_=3190+/-100K and T_eff,2_=2990+/-110K; both are slightly cooler than theoretical models predict, but consistent with other M-dwarfs of similar masses that have previously been studied. We also measure significant H{alpha} emission from both components of the binary system, and discuss this in the context of the correlation between stellar activity and the discrepancies between the observed and model temperatures.
- ID:
- ivo://CDS.VizieR/J/A+A/446/515
- Title:
- Distances of nearby ultracool dwarfs
- Short Name:
- J/A+A/446/515
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present updated results of spectroscopic follow-up observations of a sample of 45 M dwarf candidates identified by Phan-Bao et al. (2003, Cat. <J/A+A/401/959>) based on the DENIS photometry and proper motion measurements. Forty one of these are nearby late-M dwarfs (d<30pc) with spectral types ranging from M5.0 to M8.5 computed from the spectral indices. One contaminant is probably an F-G main sequence star reddened by intervening dust and three stars that were not observed have previous classifications as M dwarfs in the literature. In this paper, we identify three M7.5, five M8.0, one M8.5 dwarf and confirm two new M8.0 dwarf members of the 25pc volume.
