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 X = (2.4 ± 0.05) × 10 25 ergs s -1 and log( L X / L bol ) = -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.