Optical Identification and Spectroscopy of EUV Sources

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Session 80 -- Stellar Activity II: Early Type Stars, Normal Stars
Display presentation, Wednesday, 11, 1995, 9:20am - 6:30pm

[80.14] Optical Identification and Spectroscopy of EUV Sources

N.Craig, A.Fruscione, M.Abbott, C.A.Christian, J.J.Drake, J.Dupuis, M.Mathioudakis (CEA/UCB), R.Green, T.Boroson (KPNO)

We present optical identification and analysis of previously unidentified extreme ultraviolet (EUV) sources (60--200 \AA) discovered with the Extreme Ultraviolet Explorer (EUVE) during the all-sky and deep surveys. Two EUVE deep survey sources, EUVE\_J0318+184 and EUVE\_J2056-171, are identified as active, young, late-type stars. They display strong H$\alpha$, Ca~{\sc ii} H and K emission, and Li 6707.8 \AA\ absorption suggesting spectral types of dM0e. A very strong flare with energy in excess of $10^{35}$~erg was also observed on EUVE\_J2056-171 (Mathioudakis et al.\ 1994, in prep.). We also identified four previously cataloged EUVE sources: EUVE\_J1918+59.9, EUVE\_J2249+58.5, EUVE\_J0419+21.7, and EUVE\_J2329+41.4. The first two sources are identified in both the ROSAT Wide Field Camera and the EUVE catalogs as unclassified ``stars.'' They are in fact hot DA white dwarfs showing a clean optical spectrum with broad Balmer lines. EUVE\_J0419+21.7 was previously assigned a possible identification with 56 Tau, an A0sp star. Optical spectra of other candidates within the error circle, in addition to the bright A star, show three emission line dMe stars in the field. We attribute the EUV emission to one or more of this collection of dMe stars. The source EUVE\_J2329+41.4 is currently identified as probably being G~190--28 with spectral type M. However we show that both G~190--28 and G~190--27 are dMe stars and are located within the error circle of the EUVE position of this source, and therefore both of these stars probably contribute to the EUV emission.\\ This work has been supported by NASA contract NAS5-29298.

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