New M Dwarfs in the Solar Neighborhood

New M Dwarfs in the Solar Neighborhood NEWMDWARFS ivo://nasa.heasarc/newmdwarfs NASA/GSFC HEASARC Riaz et al. 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source This table contains the results from a spectroscopic study of 1080 nearby active M dwarfs, selected by correlating the Two Micron All Sky Survey (2MASS) and ROSAT catalogs at galactic latitudes greater than 15 degrees above or below the Galactic Plane and using a matching radius of 20 arcseconds, as well as color cuts (J-H < 0.75, H-K > 0.15 and 0.8 < J-K < 1.1) designed to select M dwarfs. The authors have derived the spectral types and estimated distances for all of their stars. The spectral types range between K5 and M6. Nearly half of the stars lie within 50 pc. The authors have measured the equivalent width of the H-alpha emission line. Their targets show an increase in chromospheric activity from early to mid-spectral types, with a peak in activity around M5. Using the count rate and hardness ratios obtained from the ROSAT catalog,the authors have derived the stellar X-ray luminosities. Their stars display a "saturation-type" relation between the chromospheric and coronal activity. The relation is such that log LX/Lbol remains "saturated" at a value of approximately -3 for varying H-alpha equivalent width. The authors have found 568 matches in the USNO-B catalog and have derived the tangential velocities vtan for these stars. There is a slight trend of decreasing chromospheric activity with age, such that the stars with higher vtan values have lower H-alpha equivalent widths. The coronal emission, however, remains saturated at a value of log LX/Lbol ~ -3 for varying tangential velocities, suggesting that the coronal activity remains saturated with age. The authors do not find any break in the saturation-type relation at the spectral type at which stars become fully convective (~M3.5). Most of the stars in their sample show more coronal emission than the dMe stars in the Hyades and Praesepe clusters and have vtan < 40 km s-1, suggesting that they belong to a young population. This table was created by the HEASARC in March 2010 based on the (corrected) electronic version of Table 1 from the reference paper which was obtained from the Astronomical Journal web site. This is a service provided by NASA HEASARC . 2006AJ....132..866R https://heasarc.gsfc.nasa.gov/W3Browse/all/newmdwarfs.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=newmdwarfs& GET text/xml 180 99999 true 162.537958333333 -88.998333333333 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=newmdwarfs GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_newmdwarfs&Action=More+Options&Action=Parameter+Search&ConeAdd=1 STAR CATALOG 0.0166666666666667 Infrared X-ray public newmdwarfs New M Dwarfs in the Solar Neighborhood name The 2MASS Source Identification meta.id;meta.main char nullable ra Right Ascension degree pos.eq.ra;meta.main double nullable dec Declination degree pos.eq.dec;meta.main double nullable jmag 2MASS J Band Magnitude mag phot.mag;em.IR.J double nullable hmag 2MASS H Band Magnitude mag phot.mag;em.IR.H double nullable kmag 2MASS K Band Magnitude mag phot.mag;em.IR.K double nullable spect_type Spectral Type src.spType char nullable "distance" Distance (pc) pc pos.distance short nullable log_lx_lbol Logarithm of the Ratio of the X-Ray and Bolometric Luminosities phys.luminosity;arith.ratio double nullable "__x_ra_dec" System unit vector column double nullable "__y_ra_dec" System unit vector column double nullable "__z_ra_dec" System unit vector column double nullable "__row" System index column char nullable cah1_index The CaH1 Index arith;phot.mag;em.opt double nullable tangential_velocity Tangential Velocity (km/s) km/s phys.veloc.transverse short nullable bii Galactic Latitude degree pos.galactic.lat double nullable class Browse Object Classification src.class short nullable lii Galactic Longitude degree pos.galactic.lon double nullable cah2_index The CaH2 Index arith;phot.mag;em.opt double nullable tio5_index The TiO5 Index arith;phot.mag;em.opt double nullable halpha_ew H_Alpha Equivalent Width (Angstroms) Angstrom spect.line.eqWidth;em.line.Halpha double nullable parallax_distance Parallax Distance (pc) pc pos.distance short nullable cah3_index The CaH3 Index arith;phot.mag;em.opt double nullable alt_name Other Source Designation meta.id char nullable