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New EUV Selected Flare Stars

Published online by Cambridge University Press:  12 April 2016

Bill Ball
Affiliation:
Centre for Astrophysics, University of Central Lancashire, Preston PR1 2HE, UK
Gordon Bromage
Affiliation:
Centre for Astrophysics, University of Central Lancashire, Preston PR1 2HE, UK

Extract

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The ROSAT Wide Field Camera all-sky EUV survey of 1990-91 identified over 200 active late-type stars (Pounds et al. 1993). Most of these were not known to be active prior to the survey and follow-up optical spectroscopy has been successful in selecting the most active dMe stars. These stars are characterized by their Balmer line emission which is direct evidence for an active chromosphere. We present photometric monitoring data for 4 new dMe stars, including the discovery of flaring activity on all 4 stars.

The observations were made at the South African Astronomical Observatory at Sutherland near Capetown in October 1994, using the 0.5m and 1.9m telescopes for photometry and spectrometry, respectively. The 0.5m telescope is equipped with an automated, pulse-counting photometer. Flare monitoring of all the stars was done in the U-band with either 5 or 10 s integration times. All the stars monitored were between magnitude V = 11 and 13. A total of 15 flares were detected, including at least one on each star (Table 1). Comparison stars were measured in standard UBVRI photometric bands for each star.

Type
Flares in Late-type Stars: Radio and Optical
Copyright
Copyright © Springer-Verlag 1995

References

Hawley, S.L., Pettersen, B.R., 1991, ApJ 378, 725 CrossRefGoogle Scholar
Pounds, K.A., et al., 1993, MNRAS 260, 77 Google Scholar