Confirmation of the Swift 54-second period and detection of a strong C V absorption edge in a deep XMM-Newton observation of V339 Del
ATel #5626; J. U. Ness (ESA/ESAC), G. J. Schwarz (AAS), K. L. Page and J. P. Osborne (Univ. of Leicester), M. F. Bode (Liverpool John Moores Univ.), S. N. Shore (Univ. of Pisa and INFN-Pisa), D. van Rossum (Univ of Chicago), S. Starrfield (Arizona State Univ), F. Walter (SUNY-Stony Brook), C. E. Woodward (Univ. of Minn.)
on 4 Dec 2013; 10:05 UT
Distributed as an Instant Email Notice Novae
Credential Certification: Jan-Uwe Ness (juness@sciops.esa.int)
Nova V339 Del was observed simultaneously with HST and with XMM-Newton on 21 November 2013, 99 days after outburst. The HST observations are described in ATel#5624. XMM-Newton observed for 34000 seconds, and timing and spectral information can be extracted from two MOS detectors as part of the European Photon Imaging Cameras (EPIC) and two Reflection Grating Spectrometers (RGS). The independent MOS and the RGS light curves are variable by ~10% around 60 and 30 counts per second, respectively. Both light curves contain the same periodic signal at 54.06 seconds with a FWHM of the peak in the power spectrum of 0.07 seconds. The normalized power exceeds a value of 150 where only a power of 16.6 is needed for a 99.9% detection probability. This signal has also been seen in the Swift data as reported in ATel#5573, but we detect no low-frequency noise. The strength of this signal is variable during the 8.5 hour observation but seems not to correlate with the X-ray brightness. Also the value of the period varies during the observation assuming values between 53.2 seconds and 54.8 seconds. The optical monitor was operated in the UVW2 filter in timing mode with 0.5-second time resolution and does not show the 54-second period.
The RGS spectrum covers the spectral range 6-38A and is similar to an earlier Chandra spectrum described in ATel#5593. We confirm the blue shift of 1200 km/s in strong absorption lines of the ions CV, CVI, NVI, and NVII. A strong absorption edge at 31.6A caused by photoionisation
of CV into CVI is evident, however, the photo ionisation edge of CVI into full ioniation is not present. We also see interstellar neutral absorption lines of OI and NI. The continuum is difficult to constrain by a model, particularly without the soft tail that constrains NH, but the Wien tail suggests a temperature of some 30eV (350kK) assuming NH~10^21 cm^-2, similar to that determined in ATel#5593.
