New M Dwarfs in the Solar Neighborhood

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 L_X/L_bol 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 v_tan for these stars. There is a slight trend of decreasing chromospheric activity with age, such that the stars with higher v_tan values have lower H-alpha equivalent widths.

The coronal emission, however, remains saturated at a value of log L_X/L_bol ~ -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 v_tan < 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 .