Swift-XRT detection of supersoft emission in V572 Vel
ATel #17425; K. L. Page (U. Leicester), G. J. M. Luna (UNAHUR/CONICET) and N. P.M. Kuin (UCL/MSSL)
on 29 Sep 2025; 16:08 UT
Credential Certification: Kim Page (kpa@star.le.ac.uk)
The eruption of V572 Vel (Nova Vel 2025; PNV J10251200-5331109) was
discovered on June 25.44 (CBET #5574). Swift monitoring started less
than a day later (ATel #17262), although no X-rays were detected at
this time. Regular observations continued, with the first detection of
X-ray emission occurring on August 31 (67 days after eruption; ATel
#17367). At this time, the X-ray spectrum was heavily absorbed, and a
count rate of 0.030 +0.005/-0.004 count s-1 was measured.
Observations on September 6 and 10 also revealed heavily-absorbed
X-ray spectra which could be characterised by a single temperature
optically-thin component. The next observation, taken on September 28
(day 95), however, showed a factor of greater than three increase in
count rate (0.158 +0.019/-0.017 count s-1 compared with
0.042 +/- 0.005 count s-1 on September 10), with a new,
much softer component. The soft emission can be roughly parameterised
with a blackbody of kT = 15 +4/-3 eV. The underlying optically-thin
component remains, and NH has decreased to a value
consistent with the ISM absorption in this direction (2.8 x
1021 cm-2). The 0.3-10 keV observed flux is now
1.2 x 10-11 erg cm-2 s-1.
Continued Swift monitoring has been requested. We thank the Swift PI
and deputies for approving these observations, and the Swift
operations team for implementing them.
