- 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.
Number of results to display per page
Search Results
- 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/A+A/441/653
- Title:
- 32 DENIS nearby red dwarfs
- Short Name:
- J/A+A/441/653
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present spectra of 36 nearby star candidates and 3 red giant candidates, identified in the DENIS database. 32 of the dwarf candidates are nearby red dwarfs, with spectral types from M5.5 to M8.5. Out of 11 targets with low proper motion (mu<0.1arcsec/yr) but a Reduced Proper Motion above an inclusive threshold, 9 are red dwarfs. The 4 contaminants are all reddened F-K main sequence stars, and could have been eliminated by checking for small well-known high latitude molecular clouds. These stars might be of interest as probes of interstellar absorption. For the red dwarfs we derive spectral types and spectroscopic distances, using a new calibration of the PC3 spectral index to absolute magnitudes in the I, J, H and K photometric bands. We confirm 2 new members of the 12 pc volume (2 new M8.5), and one M7.5 NLTT object closer than 10pc; and show that one quarter of the stars with photometric distances under 30pc have too small a proper motion for inclusion in the NLTT catalog.
- ID:
- ivo://CDS.VizieR/J/A+A/390/491
- Title:
- DENIS new nearby stars
- Short Name:
- J/A+A/390/491
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new nearby stars extracted from a proper motion catalogue and having a DENIS counterpart. Their distances and spectral type are estimated using the DENIS colours. 107 stars are within 50pc. 31 stars among them have previously measured distances. In addition, 40 stars may enter within the 50pc limit depending on which population they belong to. 6 stars among them have already measured distances. 5 objects, LHS5045, L225-57, LP831-45, LHS1767, and WT792, are probably closer than 15pc, with L225-57 at 9.5pc. Most of these stars are M-type while 4 stars are white dwarfs. 88 M-dwarfs are disc stars, 14 belong to the thick disc and 1 to the spheroid.
- 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/A+A/622/A114
- Title:
- Detached eclipsing binaries MITSuME photometry
- Short Name:
- J/A+A/622/A114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of the combined photometric and spectroscopic analysis of three detached eclipsing binaries (DEBs), the secondary components of which are not visible or are very hard to identify in the optical spectra - ASAS J052743-0359.7, ASAS J065134-2211.5, and ASAS J073507-0905.7. The first one is the known visual binary ADS~4022, and we found that it is a quadruple system composed of two spectroscopic binaries, one of which shows eclipses.
- ID:
- ivo://CDS.VizieR/J/ApJ/872/85
- Title:
- Detached eclipsing binaries with Gaia parallaxes
- Short Name:
- J/ApJ/872/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a sample of 81 Galactic, detached eclipsing binary stars we investigated the global zero-point shift of their parallaxes with the Gaia Data Release 2 (DR2) parallaxes. The stars in the sample lay in a distance range of 0.04-2kpc from the Sun. The photometric parallaxes {omega}_Phot_ of the eclipsing binaries were determined by applying a number of empirical surface brightness-color (SBC) relations calibrated on optical-infrared colors. For each SBC relation we calculated the individual differences d{varpi}_i_=({varpi}_Gaia_-{varpi}_Phot_)_i_ and then we calculated unweighted and weighted means. As the sample covers the whole sky we interpret the weighted means as the global shifts of the Gaia DR2 parallaxes with respect to our eclipsing binary sample. Depending on the choice of the SBC relation the shifts vary from -0.094 to -0.025mas. The weighted mean of the zero-point shift from all colors and calibrations used is d{omega}=-0.054+/-0.024mas. However, the SBC relations based on (B-K) and (V-K) colors, which are the least reddening dependent and have the lowest intrinsic dispersions, give a zero-point shift of d{omega}=-0.031+/-0.011mas in full agreement with results obtained by Lindegren+ (2018A&A...616A...2L) and Arenou+ (2018A&A...616A..17A). Our result confirms the global shift of Gaia DR2 parallaxes of d{omega}=-0.029mas reported by the Gaia team, but we do not confirm the larger zero-point shift reported by a number of follow-up papers.
- ID:
- ivo://CDS.VizieR/J/ApJS/190/77
- Title:
- Detailed analysis of cool WDs in the SDSS
- Short Name:
- J/ApJS/190/77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical spectroscopy and near-infrared photometry of 126 cool white dwarfs (WDs) in the Sloan Digital Sky Survey (SDSS DR3). Our sample includes high proper motion targets selected using the SDSS and USNO-B astrometry and a dozen previously known ultracool WD candidates. Our optical spectroscopic observations demonstrate that a clean selection of large samples of cool WDs in the SDSS (and the SkyMapper, Pan-STARRS, and the Large Synoptic Survey Telescope data sets) is possible using a reduced proper motion diagram and a tangential velocity cut-off (depending on the proper motion accuracy) of 30km/s. Our near-infrared observations reveal eight new stars with significant absorption. We use the optical and near-infrared photometry to perform a detailed model atmosphere analysis. More than 80% of the stars in our sample are consistent with either pure hydrogen or pure helium atmospheres. However, the eight stars with significant infrared absorption and the majority of the previously known ultracool WD candidates are best explained with mixed hydrogen and helium atmosphere models. The age distribution of our sample is consistent with a Galactic disk age of 8Gyr. A few ultracool WDs may be as old as 12-13Gyr, but our models have problems matching the spectral energy distributions of these objects. There are only two halo WD candidates in our sample. However, trigonometric parallax observations are required for accurate mass and age determinations and to confirm their membership in the halo.
- ID:
- ivo://CDS.VizieR/J/A+A/372/85
- Title:
- Detected sources at 12{mu}m in 47 Tuc
- Short Name:
- J/A+A/372/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The present paper investigates the properties of the dust mass loss in stars populating the giant branch of the globular cluster 47 Tuc, by combining ISOCAM and DENIS data. Raster maps of 5 fields covering areas ranging from 4x4 to 15x15arcmin^2^ at different distances from the center of the cluster have been obtained with ISOCAM at 11.5{mu}m (LW10 filter). The covered fields include most of the red variables known in this cluster. A detection threshold of about 0.2 mJy is achieved, allowing us to detect giant stars at 11.5{mu}m all the way down to the horizontal branch. No dust-enshrouded asymptotic giant branch stars have been found in the observed fields, contrary to the situation encountered in LMC/SMC globular clusters with larger turnoff masses. The color index [12]-[2] (based on the ISO 11.5{mu}m flux and on the DENIS K_S_ magnitude) is used as a diagnostic of dust emission (and hence dust mass loss). Its evolution with luminosity along the giant branch reveals that dust mass loss is only present in V3 (the only cluster Mira variable observed in the present study) and in V18, a star presenting intermittent variability. This conclusion confirms the importance of stellar pulsations in the dust formation and ensuing mass loss.
- ID:
- ivo://CDS.VizieR/J/MNRAS/353/601
- Title:
- 2dF survey of the Small Magellanic Cloud
- Short Name:
- J/MNRAS/353/601
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of new spectral types for hot, luminous stars in the Small Magellanic Cloud. The catalogue contains 4161 objects, giving an order of magnitude increase in the number of SMC stars with published spectroscopic classifications. The targets are primarily B- and A-type stars (2862 and 853 objects respectively), with 1 Wolf-Rayet, 139 O-type, and 306 FG stars, sampling the main sequence to ~mid-B. The selection and classification criteria are described, and objects of particular interest are discussed, including UV-selected targets from the Ultraviolet Imaging Telescope (UIT) experiment, Be and B[e] stars, `anomalous A supergiants', and composite-spectrum systems. We examine the incidence of Balmer-line emission, and the relationship between H-gamma equivalent width and absolute magnitude for BA stars.
