The Quiescent Corona of VB 10
We present results from a Chandra ACIS observation of the M8 dwarf star VB 10, a star near the hydrogen-burning mass limit. Until now, VB 10 has only been detected to flare at X-ray wavelengths. We can now report that nonflare, “quiescent,” X-ray emission has been detected with a luminosity, L<SUB>X</SUB>=(2.4+/-0.05)×10<SUP>25</SUP> ergs s<SUP>-1</SUP> and log(L<SUB>X</SUB>/L<SUB>bol</SUB>)=-4.9. This is consistent with the previous ROSAT nondetections of quiescent emission from VB 10. We discuss the implications of this discovery for the nature of coronae in ultracool dwarfs.