Fireworks and surprises from two recent luminous novae |
TYPE | Astrophysics Seminar |
Speaker: | Marina Orio |
Affiliation: | NAF - Osservatorio Astronomico di Padova, Italy and Department of Astronomy, University of Wisconsin, Madison WI, USA |
Date: | 08.12.2021 |
Time: | 14:30 |
Location: | Lidow 620 |
Abstract: | In the Summer of 2021 two interesting nova outbursts were observed: the eruption of V1674 Her, a nova with a highly magnetized white dwarf, and the seventh observed explosion of RS Oph, a sort of Rosetta stone of symbiotic recurrent novae. RS Oph appears to host a massive carbon-oxygen white dwarf and is a candidate progenitor of a thermonuclear supernova. Both novae were observed at all wavelengths, from gamma rays (even with Cherenkov telescopes for RS Oph) to radio. This talk will focus especially on the X-ray range. Both novae became extremely luminous, allowing high resolution spectra to be taken with X-ray gratings, and both showed intriguing modulations of the supersoft X-ray flux. V1674 Her displayed a periodic pulsation every 501 seconds, and RS Oph, exactly like in its 2006 outburst, a quasi-periodic pulsations about every 35 seconds. These periodicities are difficult to model and understand, but they reveal some fundamental physics of the underlying white dwarf undergoing shell nuclear burning.
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