- ID:
- ivo://CDS.VizieR/J/AJ/130/1680
- Title:
- LSPM-North proper-motion catalog nearby stars
- Short Name:
- J/AJ/130/1680
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A list of 4131 dwarfs, subgiants, and giants located or suspected to be located within 33pc of the Sun is presented. All the stars are drawn from the new Lepine Shara Proper Motion (LSPM)-North catalog (Cat. <I/298>) of 61,976 stars with annual proper motions larger than 0.15"/yr. Trigonometric parallax measurements are found in the literature for 1676 of the stars in the sample; photometric and spectroscopic distance moduli are found for another 783 objects. The remaining 1672 objects are reported here as nearby star candidates for the first time. Photometric distance moduli are calculated for the new stars based on the (M_V_, V-J) relationship, calibrated with the subsample of stars that have trigonometric parallaxes. The list of new candidates includes 539 stars that are suspected to be within 25pc of the Sun, including 63 stars estimated to be within only 15pc.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/814/118
- Title:
- L/T transition dwarfs search with PS1 & WISE. II.
- Short Name:
- J/ApJ/814/118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The evolution of brown dwarfs from L to T spectral types is one of the least understood aspects of the ultracool population, partly for lack of a large, well-defined, and well-characterized sample in the L/T transition. To improve the existing census, we have searched ~28000deg^2^ using the Pan-STARRS1 and Wide-field Infrared Survey Explorer surveys for L/T transition dwarfs within 25pc. We present 130 ultracool dwarf discoveries with estimated distances ~9-130pc, including 21 that were independently discovered by other authors and 3 that were previously identified as photometric candidates. Seventy-nine of our objects have near-IR spectral types of L6-T4.5, the most L/T transition dwarfs from any search to date, and we have increased the census of L9-T1.5 objects within 25pc by over 50%. The color distribution of our discoveries provides further evidence for the "L/T gap", a deficit of objects with (J-K)_MKO_~0.0-0.5mag in the L/T transition, and thus reinforces the idea that the transition from cloudy to clear photospheres occurs rapidly. Among our discoveries are 31 candidate binaries based on their low-resolution spectral features. Two of these candidates are common proper motion companions to nearby main sequence stars; if confirmed as binaries, these would be rare benchmark systems with the potential to stringently test ultracool evolutionary models. Our search also serendipitously identified 23 late-M and L dwarfs with spectroscopic signs of low gravity implying youth, including 10 with vl-g or int-g gravity classifications and another 13 with indications of low gravity whose spectral types or modest spectral signal-to-noise ratio do not allow us to assign formal classifications. Finally, we identify 10 candidate members of nearby young moving groups (YMG) with spectral types L7-T4.5, including three showing spectroscopic signs of low gravity. If confirmed, any of these would be among the coolest known YMG members and would help to determine the effective temperature at which young brown dwarfs cross the L/T transition.
- ID:
- ivo://CDS.VizieR/J/A+A/529/A108
- Title:
- Lupus clouds proper motion study with VO
- Short Name:
- J/A+A/529/A108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Lupus dark cloud complex is a well-known, nearby low-mass star-forming region, probably associated with the Gould Belt. In recent years, the number of stellar and substellar Lupus candidate members has been remarkably increased thanks to the Cores to Disks (c2d) Spitzer Legacy Program and other studies. However, most of these newly discovered objects still lack confirmation that they belong to the dark clouds. By using available kinematical information, we test the membership of the new Lupus candidate members proposed by the c2d program and by a complementary optical survey. We also investigate the relationship between the proper motions and other properties of the objects, in order to get some clues about their formation and early evolution. We compiled a list of members and possible members of Lupus 1, 3, and 4, together with all available information on their spectral types, disks, and physical parameters. Using Virtual Observatory tools, we cross-matched this list with the available astrometric catalogues to get proper motions for our objects. Our final sample contains sources with magnitudes I<16mag and estimated masses >~0.1M_{sun}_.
- ID:
- ivo://CDS.VizieR/III/70
- Title:
- Luyten's White Dwarf Catalogues
- Short Name:
- III/70
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalogue includes all probable white dwarf and degenerate stars found in the Proper Motion and Faint Blue Star Surveys conducted by W.J. Luyten. The catalogue was originally published in two booklets, one in 1970 (3035 entries), and the part II in 1977 (3511 entries). As a guideline for the inclusion of stars into this catalogue, the author has used stars which present minimal values of the combined proper motions - magnitude quantity H defined by H = m + 5 + 5 log {mu} ({mu} is the proper motion in arcsec/yr) which show the minimal H values according to the color class: b 13.5 f 15.5 g-k 17.7 a 14.4 g 17.0 k 18.3 with the following exceptions: a) evidence from photoelectric colors or spectra indicate the object is a degenerate star (e.g. LB 3303) or b) the object is close to the antapex (which is the case for many stars at alpha=21h and delta =+42{deg}, plate 234). The bluest stars (color classes b or a) will probably prove to be genuine white dwarfs; probably no more than 40% of the yellower objects (color class k) will prove to be genuine degenerates.
- ID:
- ivo://CDS.VizieR/J/ApJ/869/9
- Title:
- Machine-learning investigation of the open cluster M67
- Short Name:
- J/ApJ/869/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we use a machine-learning method, random forest (RF), to identify reliable members of the old (4Gyr) open cluster M67 based on the high-precision astrometry and photometry taken from the second Gaia data release (Gaia-DR2). The RF method is used to calculate membership probabilities of 71117 stars within 2.5{deg} of the cluster center in an 11-dimensional parameter space, the photometric data are also taken into account. Based on the RF membership probabilities, we obtain 1502 likely cluster members (>=0.6), 1361 of which are high-probability cluster members (>=0.8). Based on high-probability memberships with high-precision astrometric data, the mean parallax (distance) and proper-motion of the cluster are determined to be 1.1327+/-0.0018mas (883+/-1pc) and (<{mu}_{alpha}_cos{delta}>,<{mu}_{delta}_>)=(-10.9378+/-0.0078,-2.9465 +/-0.0074)mas/yr, respectively. We find the cluster to have a mean radial velocity of +34.06+/-0.09km/s, using 74 high-probability cluster members with precise radial-velocity measures. We investigate the spatial structure of the cluster, the core and limiting radius are determined to be 4.80'+/-0.11' (~1.23+/-0.03pc) and 61.98'+/-1.50' (~15.92+/-0.39pc), respectively. Our results reveal that an escaped member with high membership probability (~0.91) is located at a distance of 77' (~20pc) from the cluster center. Furthermore, our results reveal that at least 26.4% of the main-sequence stars in M67 are binary stars. We confirm that significant mass segregation has taken place within M67.
- ID:
- ivo://CDS.VizieR/J/MNRAS/434/3236
- Title:
- Masses of Praesepe members
- Short Name:
- J/MNRAS/434/3236
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have determined possible cluster members of the nearby open cluster Praesepe (M44) based on J and K photometry and proper motions from the PPMXL catalogue and z photometry from the Sloan Digital Sky Survey. In total, we identified 893 possible cluster members down to a magnitude of J=15.5mag, corresponding to a mass of about 0.15M_{sun}_ for an assumed cluster distance modulus of (m-M)0=6.30mag (d~182pc), within a radius of 3.5{deg} around the cluster centre. We derive a new cluster centre for Praesepe (RA_centre_=8:39:37, DE_centre_=19:35:02). We also derive a total cluster mass of about 630M_{sun}_, and a 2D half-number and half-mass radius of 4.25 and 3.90pc, respectively.
- ID:
- ivo://CDS.VizieR/J/A+A/540/A57
- Title:
- Mass function of Quintuplet cluster
- Short Name:
- J/A+A/540/A57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The stellar mass function is a probe for a potential dependence of star formation on the environment. Only a few young clusters are known to reside within the central molecular zone and can serve as test-beds for star formation under the extreme conditions in this region. We determine the present-day mass function of the Quintuplet cluster, a young massive cluster in the vicinity of the Galactic centre. We use two epochs of high resolution near infrared imaging data obtained with NAOS/CONICA at the ESO VLT to measure the individual proper motions of stars in the Quintuplet cluster in the cluster reference frame. An unbiased sample of cluster members within a radius of 0.5pc from the cluster centre was established based on their common motion with respect to the field and a subsequent colour-cut. Initial stellar masses were inferred from four isochrones covering ages from 3 to 5Myr and two sets of stellar evolution models. For each isochrone, the present-day mass function of stars was determined for the full sample of main sequence cluster members using an equal number binning scheme. We find the slope of the present-day mass function in the central part of the Quintuplet cluster to be alpha=-1.68^+0.13^_-0.09_ for an approximate mass range from 5 to 40M_{sun}_, which is significantly flatter than the Salpeter slope of alpha=-2.35. The flattening of the present-day mass function may be caused by rapid dynamical evolution of the cluster in the strong Galactic centre tidal field. The derived mass function slope is compared to the values found in other young massive clusters in the Galaxy.
- ID:
- ivo://CDS.VizieR/J/MNRAS/455/357
- Title:
- 2MASS J18212815+1414010 field stars
- Short Name:
- J/MNRAS/455/357
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used the OSIRIS camera at the 10.4m Gran Telescopio Canarias (GTC) to monitor the astrometric motion of the L4.5 dwarf 2M1821+14 over 17 months. The astrometric residuals of 11 epochs have an rms dispersion of 0.4mas, which is larger than the average precision of 0.23mas per epoch and hints towards an additional signal or excess noise. Comparison of the point-spread functions in OSIRIS and FORS2/VLT images reveals no differences critical for high-precision astrometry, despite the GTC's segmented primary mirror. We attribute the excess noise to an unknown effect that may be uncovered with additional data. For 2M1821+14, we measured a relative parallax of 10^6.15^+/-0.18mas and determined a correction of 0.50+/-0.05mas to absolute parallax, leading to a distance of 9.38+/-0.03pc. We excluded at 3{sigma} confidence the presence of a companion to 2M1821+14 down to a mass ratio of 0.1 (~5M_Jupiter_) with a period of 50-1000d and a separation of 0.1-0.7au. The accurate parallax allowed us to estimate the age and mass of 2M1821+14 of 120-700Myr and 0.049^+0.014^_-0.024_M_{sun}_, thus confirming its intermediate age and substellar mass. We complement our study with a parallax and proper motion catalogue of 587 stars (i'=~15.5-22) close to 2M1821+14, used as astrometric references. This study demonstrates submas astrometry with the GTC, a capability applicable for a variety of science cases including the search for extrasolar planets and relevant for future astrometric observations with E-ELT and TMT.
- ID:
- ivo://CDS.VizieR/J/AJ/159/52
- Title:
- M dwarfs at high spectral-resolution in Y band
- Short Name:
- J/AJ/159/52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In young Sun-like stars and field M-dwarf stars, chromospheric and coronal magnetic activity indicators such as H{alpha}, X-ray, and radio emission are known to saturate with low Rossby number (Ro<~0.1), defined as the ratio of rotation period to convective turnover time. The mechanism for the saturation is unclear. In this paper, we use photospheric TiI and CaI absorption lines in the Y band to investigate magnetic field strength in M dwarfs for Rossby numbers between 0.01 and 1.0. The equivalent widths of the lines are magnetically enhanced by photospheric spots, a global field, or a combination of the two. The equivalent widths behave qualitatively similar to the chromospheric and coronal indicators: we see increasing equivalent widths (increasing absorption) with decreasing Ro and saturation of the equivalent widths for Ro<~0.1. The majority of M dwarfs in this study are fully convective. The results add to mounting evidence that the magnetic saturation mechanism occurs at or beneath the stellar photosphere.
- ID:
- ivo://CDS.VizieR/J/AJ/129/2428
- Title:
- M dwarf-white dwarf binary systems
- Short Name:
- J/AJ/129/2428
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the relationship between age and chromospheric activity for 139 M dwarf stars in wide binary systems with white dwarf companions. We present the measured radial velocities and complete space motions for 161 white dwarf stars in wide binaries.
