NUVBEMDCAT - Near-UV Detected Bright Early-M Dwarf Star Catalog

Overview

Planets orbiting within the close-in habitable zones of M dwarf stars will be exposed to elevated high-energy radiation driven by strong magnetohydrodynamic dynamos during stellar youth. Near-ultraviolet (NUV) irradiation can erode and alter the chemistry of planetary atmospheres, and a quantitative description of the evolution of NUV emission from M dwarfs is needed when modeling these effects. The authors investigated the NUV luminosity evolution of early M-type dwarfs by cross-correlating the Lepine & Gaidos (LG11: 2011, AJ, 142, 138) catalog of bright M dwarfs (available at the HEASARC as the MDWARFASC table) with the Galaxy Evolution Explorer (GALEX) catalog of NUV (1771-2831 Angstrom) sources. Of the 4,805 sources with GALEX counterparts, 797 have NUV emission significantly (> 2.5 sigma) in excess of an empirical basal level. The authors inspected these candidate active stars using visible-wavelength spectra, high-resolution adaptive optics imaging, time-series photometry, and literature searches to identify cases where the elevated NUV emission is due to unresolved background sources or stellar companions; they estimated the overall occurrence of these "false positives" (FPs) as ~ 16%. The authors constructed an NUV luminosity function that accounted for FPs, detection biases of the source catalogs, and GALEX upper limits. They found the NUV luminosity function to be inconsistent with predictions from a constant star-formation rate and simplified age-activity relation defined by a two-parameter power law.

Catalog Bibcode

2015ApJ...798...41A

References

The Near-ultraviolet Luminosity Function of Young, Early M-type Dwarf Stars
   Ansdell M., Gaidos E., Mann A.W., Lepine S., James D., Buccino A., Baranec
   C., Law N.M., Riddle R., Mauas P., Petrucci R.
   <Astrophys. J., 798, 41 (2015)>
   =2015ApJ...798...41A (SIMBAD/NED BibCode)

Provenance

This table was created by the HEASARC in March 2015 based on an electronic versions of Table 4 from the reference paper which was obtained from the ApJ web site.

HEASARC Implementation

The original table did not contain any positions for these stars. The HEASARC obtained them from the Lepine & Gaidos (LG11) catalog of bright M dwarfs (available at the HEASARC as the MDWARFASC table). These positions thus correspond to the 2000.0 epoch and not to their actual positions at the time of the GALEX observation. As noted in the reference paper, the authors' cross-correlation with LG11 included a correction for stellar proper motion between the J2000 epoch of LG11 and the epochs of the individual GALEX All-Sky Imaging Survey (AIS) observations, and a matching criterion of 5 arcseconds (the angular resolution of GALEX).

The HEASARC also notes that, whereas in the abstract the authors state that they found 797 stars satisfying their selection criteria, the ApJ table (and thus the present table) has only 794 entries.

Parameters

Name
The name of the M dwarf in LG11. As with MDWARFASC, these names have been modified by the HEASARC to conform with the naming conventions discussed in the Dictionary of Nomenclature of Celestial Objects, viz., they use a prefix of the form 'PMI J' rather than the 'PMI' prefix used in both this reference paper and LG11. These prefixes are followed by five digits which relate to the International Celestial Reference System (ICRS) right ascension (RA) of the star in sexagesimal coordinates; the first four digits are the hours and minutes of RA, the fifth digit is the seconds of RA divided by 6 and rounded down to the nearest integer. These are followed by the declination sign and then four digits which replicate the ICRS Declination (hours, then minutes) of the source. A disambiguation letter (NSEW) is used when the scheme would leave two stars with the same name, with the letter indicating the relative orientation of the stars in the pair.

RA
The Right Ascension of the star in the selected equinox taken from LG11 (the MDWARFASC table in the HEASARC database). This was given in decimal degree coordinates (2000.0 epoch) in the ICRS system and to a precision of 10^-6 degrees in the original table. See the HEASARC_Implementation section above for more information.

Dec
The Declination of the star in the selected equinox taken from LG11 (the MDWARFASC table in the HEASARC database). This was given in decimal degree coordinates (2000.0 epoch) in the ICRS system and to a precision of 10^-6 degrees in the original table. See the HEASARC_Implementation section above for more information.

LII
The Galactic Longitude of the star.

BII
The Galactic Latitude of the star.

Vmag
The V-band magnitude of the star.

Jmag
The J-band magnitude of the star.

NUV_K_Color
The (GALEX/NUV - K_S) color of the star. The NUV (near ultraviolet) band corresponds to the 1750-2800 Angstrom spectral range.

NUV_Flux
The GALEX NUV band (1750-2800 Angstrom) flux density of the star, in microJansky (µJy).

FUV_Flux
The GALEX far-ultraviolet (FUV: 1350-1750 Angstrom) band flux density of the star, in microJansky (µJy).

RASS_Flux
The ROSAT All-sky Survey (RASS) soft X-ray flux of the star, in erg cm^-2 s^-1. To identify stars with X-ray counterparts, the authors cross-correlated their sample with the RASS Bright Source Catalog (Voges et al. 1999 A&A, 349, 389: available in the HEASARC database as the RASSBSC table) and the Faint Source Catalog (Voges et al. 2000, IAU Circ. 7432, 1: available in the HEASARC database as the RASSFSC table). The authors used a 25-arcsecond search radius around the LG11 coordinates, corresponding to the 2-sigma ROSAT positional uncertainty determined by Voges et al. (1999). They converted the PSPC detector count rate into an X-ray flux, F_X, using the conversion factor CF from Schmitt et al. (1995, ApJ, 450, 392): CF = (5.30xHR +8.31)x 10^-12 erg cm^-2 count^-1, where HR is the first hardness ratio from the ROSAT catalog. They did not correct for proper motion for this cross-correlation, due to the large positional uncertainty of ROSAT compared to GALEX.

Halpha_EW
The H-Alpha equivalent width in the medium-resolution optical spectrum of the star, in Angstrom.

Log_R_Corr_NUV_Bol
The logarithm of the ratio of the basal-level-corrected NUV luminosity of the star to its bolometric luminosity, R'_NUV. See Section 5.1 of the reference paper for a full description of how this parameter is calculated.

Robo_AO_FP_Flag
This parameter contains a non-blank flag value [YN] indicating that the authors used a Robo-AO image (see Section 3.2 of the reference paper) to search for the presence of close visual binary secondary components which may be causing FP NUV emission (see Section 4.2.1 of the reference paper). A value of 'Y' means that one was detected which was a potential FP source, while 'N' means there is no such compromising source. Blank values for this parameter mean that this test was not applied to the given star.

Low_Halpha_FP_Flag
This parameter contains a non-blank flag value [YN] indicating that the authors used the lack of H-alpha emission as a test to see if the given star was a false positive, with values as follows:

        Y = Found as a false positive using the missing H-alpha detection
            technique (Section 4.2.2 of reference paper);
        N = Not found as a false positive using the missing H-alpha detection
            technique;
  (blank) = Not tested using the missing H-alpha detection technique.

Shifted_Halpha_FP_Flag
This parameter contains a non-blank flag value [YN] indicating that the authors used the shifted position of the H-alpha emission in SNIFS integral field spectrum as a test to see if the given star was a false positive, with values as follows:

        Y = Found as a false positive using the shifted H-alpha position
            technique (Section 4.2.3 of reference paper);
        N = Not found as a false positive using the shifted H-alpha position
            technique;
  (blank) = Not tested using the shifted H-alpha position technique.

Superwasp_FP_Flag
This parameter contains a non-blank flag value [YN] indicating that the authors used the SuperWASP lightcurve of the star to determine if the star was a short-period interacting or synchronized binary, and it was thus a false positive, with values as follows:

        Y = Found as a false positive using the SuperWASP light curve
            technique (Section 4.2.4 of reference paper);
        N = Not found as a false positive using the SuperWASP light curve
            technique;
  (blank) = Not tested using the SuperWASP light curve technique.

False_Positive_Flags
This parameter contains flag value(s) capturing the overall FP status of the star, its membership in a young moving group (YMG) and/or whether it was part of the sample used in the calculation of the NUV luminosity function (NUVLF), as follows:

      L = found as FP in literature (Section 4.1 of the reference paper);
      D = found as FP using detection techniques (Section 4.2);
      N = not found as FP in literature or by FP detection techniques;
      R = removed from NUVLF (Section 5.2);
      G = YMG member used in age-activity relation derivation (Section 6.2).

Contact Person

Questions regarding the NUVBEMDCAT database table can be addressed to the HEASARC Help Desk.

Page Author: Browse Software Development Team
Last Modified: Monday, 16-Sep-2024 17:32:27 EDT