R. Petre et al., THE BROAD-BAND X-RAY-SPECTRUM OF SN-1978K AND 2 OTHER LUMINOUS X-RAY SOURCES IN THE SPIRAL GALAXY NGC-1313, Publications of the Astronomical Society of Japan, 46(3), 1994, pp. 120000115-120000120
We present preliminary results of our analysis of the ASCA PV phase ob
servation of the nearby spiral galaxy NGC 1313. ASCA cleanly resolves
the three previously known luminous sources, one of which is the very
luminous supernova, SN 1978k. The spectrum of SN 1978k is described by
either a power law with a photon index GAMMA approximately 2.2 or a t
hermal model with temperature kT approximately 3.0 keV and abundances
Z approximately 0.2 Z.. There is no evidence for strong line emission
from it or from the other two sources. The spectrum of SN 1978k arises
either in shocked gas in extreme departure from ionization equilibriu
m or from synchrotron processes associated with a newborn pulsar. A se
cond source, near the galactic center, is well-fit by a power-law with
a photon index of approximately 1.8. It is possibly an active nucleus
-like source, but physically displaced from the optical nucleus of the
galaxy. The spectrum of the third source, located 8 kpc south of the
nucleus, along with the absence of an optical counterpart, suggests th
at it is a low-mass X-ray binary; but its high X-ray luminosity clouds
this interpretation. This observation demonstrates the ability of ASC
A to perform effective broad band spectroscopic measurements of source
s at a 2-10 keV flux level of 5 X 10(-13) erg cm-2 s-1.