Stars Grouped with Car
Nancy Remage Evans(SAO) Fredrick D. Seward (SAO), Miriam Krauss (SAO), Eric Schlegel (SAO), Scott Wolk (SAO)
Abstract
The region around the
Car nebula contains three O
associations, which provide examples of very rare objects,
including a Wolf-Rayet star and several massive O3 stars.
One of the early Chandra ACIS-I images was centered on
Car,
and included the region of Trumpler 16 (of which
Car
is a member), and also some of Trumpler 14. The Chandra image
confirms the well known result that O and very early B stars
are X-ray sources (Seward and Chlebowski, 1982, ApJ, 256, 530)
with LX
10-7 Lbol.
In addition, the new Chandra image reveals a population of
X-ray sources without O or B spectral type counterparts, which
are presumably pre-main sequence stars. Analysis is assisted by
reasonable uniformity of the optical extinction
across the association. However, X-ray results permit us
to confirm extra absorption of soft X-ray flux in
two stars which have unusually high optical extinction, and lie near
the edge of dust lanes.
The energy sensitivity of the ACIS-CCD provides low resolution spectra.
We have used these to compare spectra of the stars with different
photospheric temperatures, as well as varying stellar wind strengths.
CATEGORY: NORMAL STARS AND WHITE DWARFS