BNMDSPECAT ivo://nasa.heasarc/bnmdspecat NASA/GSFC HEASARC Lepine et al. 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source This table contains a spectroscopic catalog of the 1564 brightest (J < 9<sup>m</sup>) M-dwarf candidates in the northern sky, as selected from the SUPERBLINK proper-motion catalog (Lepine and Shara 2005, AJ, 129, 1483). Observations confirm 1408 of the candidates to be late-K and M dwarfs with spectral subtypes K7 - M6. From the low (mu > 40 mas yr<sup>-1</sup>) proper motion limit and high level of completeness of the SUPERBLINK catalog in that magnitude range, the authors estimate that their spectroscopic census most likely includes > 90% of all existing, northern-sky M dwarfs with apparent magnitude J < 9<sup>m</sup>. Only 682 stars in this sample are listed in the Third Catalog of Nearby Stars (CNS3, Gliese and Jahreiss 1991); most others are relative unknowns and have spectroscopic data presented here for the first time. Spectral subtypes are assigned based on spectral index measurements of CaH and TiO molecular bands; a comparison of spectra from the same stars obtained at different observatories, however, reveals that spectral band index measurements are dependent on spectral resolution, spectrophotometric calibration, and other instrumental factors. As a result, the authors find that a consistent classification scheme requires that spectral indices be calibrated and corrected for each observatory/instrument used. After systematic corrections and a recalibration of the subtype-index relationships for the CaH2, CaH3, TiO5, and TiO6 spectral indices, the authors find that they can consistently and reliably classify all the stars to a half-subtype precision. The use of corrected spectral indices further requires them to recalibrate the zeta parameter, a metallicity indicator based on the ratio of TiO and CaH optical bandheads. However, the authors find that their zeta values are not sensitive enough to diagnose metallicity variations in dwarfs of subtypes M2 and earlier (+/- 0.5 dex accuracy) and are only marginally useful at later M3-M5 subtypes (+/- 0.2 dex accuracy). Fits of their spectra to the Phoenix atmospheric model grid are used to estimate effective temperatures. These suggest the existence of a plateau in the M1-M3 subtype range, in agreement with model fits of infrared spectra but at odds with photometric determinations of T<sub>eff</sub>. Existing geometric parallax measurements are extracted from the literature for 624 stars, and are used to determine spectroscopic and photometric distances for all the other stars. Active dwarfs are identified from measurements of H-alpha equivalent widths, and the authors find a strong correlation between H-alpha emission in M dwarfs and detected X-ray emission from ROSAT and/or a large UV excess in the GALEX point source catalog. Proper motion data and photometric distances are combined in order to evaluate the (U, V, W) distribution in velocity space, which is found to correlate tightly with the velocity distribution of G dwarfs in the solar neighborhood. However, active stars show a smaller dispersion in their space velocities, which is consistent with those stars being younger on average. The authors state that this catalog will be very useful for guiding the selection of the best M dwarf targets for exoplanet searches, in particular those using high-precision radial velocity measurements. This online catalog was created by the HEASARC in June 2013 based on a machine-readable version of Tables 1, 3 and 7 from the paper which were obtained from the AJ website (Tables 1 and 3) or from the first author (Table 7). This is a service provided by NASA HEASARC . 2013AJ....145..102L https://heasarc.gsfc.nasa.gov/W3Browse/all/bnmdspecat.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=bnmdspecat& GET text/xml 180 99999 true 42.18121 0.034496 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=bnmdspecat GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_bnmdspecat&Action=More+Options&Action=Parameter+Search&ConeAdd=1 STAR CATALOG 0.0166666666666667 Infrared Optical public bnmdspecat Brightest M Dwarfs in the Northern Sky Spectroscopic Catalog name Source Designation 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 pm_ra Proper Motion in Right Ascension arcsec/yr pos.pm;pos.eq.ra double nullable pm_dec Proper Motion in Declination arcsec/yr pos.pm;pos.eq.dec double nullable vmag Estimated Visual Magnitude mag phot.mag;em.opt.V double nullable spect_type Adopted Spectral Type src.spType char nullable trig_parallax Trigonometric Parallax arcsec pos.parallax.trig double nullable trig_parallax_error Uncertainty in Trigonometric Parallax arcsec stat.error;pos.parallax.trig double nullable spect_parallax Spectroscopic Parallax arcsec pos.parallax.spect double nullable spect_parallax_error Uncertainty in Spectroscopic Parallax arcsec stat.error;pos.parallax.spect double nullable uvel U Component of Velocity km/s phys.veloc;pos.galactic double nullable galex_nuv_mag GALEX Near-UV Magnitude mag phot.mag;em.UV.200-300nm double nullable halpha_ew H-Alpha Equivalent Width Index Angstrom spect.line.eqWidth;em.line.Halpha double nullable rass_count_rate ROSAT X-Ray Count Rate ct/s phot.count;em.X-ray.soft double nullable vmag_flag Flag for Estimated Visual Magnitude meta.code;phot.mag;em.opt.V char nullable jmag 2MASS Infrared J Magnitude mag phot.mag;em.IR.J double nullable galex_fuv_mag GALEX Far-UV Magnitude mag phot.mag;em.UV.100-200nm double nullable ks_mag 2MASS Infrared K_s Magnitude mag phot.mag;em.IR.K double nullable spect_date Observation Date mjd time.epoch;obs double nullable t_eff Effective Temperature from Model Fit K phys.temperature.effective int nullable uv_activity_flag Flag [Y] Indicates Ultraviolet Activity meta.code;em.UV char nullable hmag 2MASS Infrared H Magnitude mag phot.mag;em.IR.H double nullable wvel W Component of Velocity km/s phys.veloc;pos.galactic double nullable vvel V Component of Velocity km/s phys.veloc;pos.galactic double nullable phot_parallax_error Uncertainty in Photometric Parallax arcsec stat.error;pos.parallax.phot double nullable xray_activity_flag Flag [Y] Indicates X-Ray Activity meta.code;em.X-ray char nullable vo1_index VO1 Spectral Index; Corrected meta.code;spect;em.opt double nullable cah2_index CaH2 Spectral Index; Corrected meta.code;spect;em.opt double nullable log_g Gravity from Model Fit log(cm/s2) phys.gravity double nullable lii Galactic Longitude degree pos.galactic.lon double nullable rass_hardness_ratio_1 ROSAT Hardness Ratio 1 phot.count;arith.ratio;em.X-ray.soft double nullable num_spect_subtype Numerical Spectral Subtype M meta.code;src.spType double nullable metallicity_index Zeta Metallicity Index phys.abund.Fe double nullable tio5_index TiO5 Spectral Index; Corrected meta.code;spect;em.opt double nullable halpha_activity_flag Flag [Y] Indicates H-Alpha Activity meta.code;em.line.Halpha char nullable phot_parallax Photometric Parallax arcsec pos.parallax.phot double nullable bii Galactic Latitude degree pos.galactic.lat double nullable cah3_index CaH3 Spectral Index; Corrected meta.code;spect;em.opt double nullable class Browse Object Classification src.class short nullable tio6_index TiO6 Spectral Index; Corrected meta.code;spect;em.opt double nullable observatory Observatory Where Observed meta.id;instr.obsty char nullable cns3_name Source Designation in the Third Catalog of Nearby Stars meta.id char nullable prev_obs_flags Flags [PM] Indicate Previous Observation: P=PMSU Survey, M=MtCN Program meta.code;obs char nullable vo2_index VO2 Spectral Index; Corrected meta.code;spect;em.opt 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