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Swift super soft X-ray detection in Nova V1213 Centauri

ATEL # 2904; G.J. Schwarz (AAS), J.P. Osborne, K.L. Page (U. Leicester), J.-U. Ness (ESAC/ESA), F.M. Walter (Stony Brook University), M.F. Bode, (LJMU), S. Starrfield (Arizona State U.), C.E. Woodward, L.A. Helton (U. Minnesota)
on 4 Oct 2010; 14:18 UT
Password Certification: Kim Page (

Subjects: Infra-Red, Optical, Ultra-Violet, X-ray, Nova

V1213 Cen was detected by Swift as a super soft X-ray source on March 26.9, 2010 with an average 0.3-10 keV count rate of 0.011 +/- 0.002 counts per second. V1213 Cen is a moderately fast classical nova with t_2 = 11 +/- 2 days based on the early AAVSO light curve. Additional Swift observations on April 27.1/28.5, July 20.3, August 17.7, and September 14.0, 2010 reveal that the source is becoming softer and brighter. The count rate on the latest Swift observation was 0.028 +/- 0.002 counts per second and can be parameterized by a blackbody fit with kT = 31 +/- 4 eV and a N_H = (6.4 +/- 1.8)e+21 cm^-2. Simultaneous uvw2 band (192.8 nm) photometry with the UVOT instrument shows a slow decline from 17.6 mag in March to 18.5 mag in the latest visit. In a Swift observation on May 22.5, 2009, or one day after visual maximum (Pojmanski et al. 2009 IAUC, 9043, 1), V1213 Cen was not detected in the X-rays to a limit of 0.032 counts per second but was a bright UV source at uvw2 = 12.9 mag. Another Swift visit is scheduled for mid-October.

Coincident with the Swift observations, we have monitored the optical spectral evolution and the BVR_cI_c and JHK light curves with SMARTS telescopes. Spectra obtained on March 24, 2010 showed strong [Fe VII] (608.7 nm) and some [Fe X] (637.5 nm) line emission. By June 27 the [Fe X] emission had increased considerably and was then brighter than the [Fe VII] line. The emergence of strong [Fe X] is consistent with the increasing super soft X-ray detection by Swift. The optical and IR light curves are typical of novae with a slow decline back to quiescence. However, beginning in late July the BVR_cI_c all brightened by about 0.8 magnitudes. This late increase is not mirrored in the JHK or the Swift uvw2 light curves which continued their declines. This curious optical phenomena is not understood at this point but we will resume monitoring of V1213 Cen as it emerges from behind the Sun.

We thank the Swift PI and operations team for their support.

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R. E. Rutledge , Editor
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