Swift-X-ray detection of nova V462 Lup
ATel #17353; K. L. Page (U. Leicester), N. P.M. Kuin (MSSL), G. J.M. Luna (UNAHUR/CONICET/Argentina),Isabel de J. Lima (UNESP/Brazil), Claudia V. Rodrigues (INPE/Brazil) and N. E. Nunez (ICATE/UNSJ/Argentina)
on 22 Aug 2025; 17:09 UT
Credential Certification: Kim Page (kpa@star.le.ac.uk)
Subjects: Ultra-Violet, X-ray, Nova
The optically-bright nova V462 Lup (Nova Lupi 2025; ASASSN-25cm; AT
2025nlr) was discovered on 2025 June 12 at 20:52:48 UT
(TNS) and classified
as a classical
nova two days later (ATel #17228). Observations with the Neil Gehrels
Swift Observatory began on 2025 June 19, with 1-2 ks exposure being
collected every few days. Because of the optical brightness, until
August 10 the UV/Optical Telescope (UVOT) had to be blocked, and the
the X-ray Telescope (XRT) operated in Windowed Timing mode, to avoid
optical loading. During this time, no X-ray source was significantly
detected.
By August 22, the nova had faded sufficiently such that the XRT could
be switched to Photon Counting mode. In 2 ks of data, a clear X-ray
source was detected, with a 0.3-10 keV count rate of (6.7 +1.8/-1.4) x
10-3 count s-1. Although only 10 source counts
were measured in this observation, the spectrum is clearly absorbed,
and can be fitted by a single-temperature optically-thin plasma with
kT > 0.5 keV and NH = (12 +38/-9) x 1022
cm-2. The observed (unabsorbed) flux over 0.3-10 keV is 1.5
(4.2) x 10-12 erg cm-2 s-1.
An ultraviolet spectrum was also taken on August 22, which shows
bright emission lines of predominantly N II and III, C II and III, O
II and III, Si II and Mg II. V462 Lup is therefore a CNO nova and has
entered the nebular phase. The emission lines reach a brightness of
approximately 10-10 erg cm-2 s-1,
with a continuum at 5x10-13 erg cm-2
s-1 A-1.
Further Swift observations are planned, and we thank the Swift PI, Brad Cenko, and his deputies for approving the time, as well as the Swift planning and operations teams for their continuing support.
