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SUMMARY:Extreme SSS and their links to HMXBs [IIA Colloquium]
DTSTART:20260203T100000Z
DTEND:20260203T110000Z
DTSTAMP:20260418T041800Z
UID:indico-event-399@events.iiap.res.in
CONTACT:colloqm@iiap.res.in
DESCRIPTION:Speakers: Phil Charles (University of Southampton)\n\nAbstract
 : V Sge is a peculiar\, highly luminous long-period (12.3h) cataclysmic v
 ariable that displays a supersoft emitting component (SSS) when in the fai
 nt phase of its V~10-13 range of variability. It appears to be undergoing 
 heavy accretion from its more massive secondary\, almost certainly at\, or
  above\, an Eddington-limited rate\, indicating that it is in a very rare\
 , short-lived phase of its binary evolution\, placing it firmly in the SSS
 -DD channel for eventually detonating as a SNIa. Its complex and highly va
 riable set of optical emission features\, from Balmer and HeII up to high 
 ionisation emission lines\, including strong fluorescence features\, have 
 made it a target of detailed spectroscopic studies going back 60 years. It
  is the brightest galactic SSS\, yet we only have poor constraints on the 
 donor properties. We have obtained VLT X-Shooter spectra of V Sge as a fun
 ction of orbital phase\, revealing multiple components in both high and lo
 w ionisation lines which have allowed us to track V Sge's principal emitti
 ng regions. These results will be placed in the wider picture of our under
 standing of mass-transfer processes in the SSS. These results will be comp
 ared with very recent results on the only BeX SSS with a He donor in the L
 MC\, and other short-lived SSS transients in the Magellanic Clouds\, indic
 ating that the long-sought Be-WD systems can be found. This has implicatio
 ns for the properties of the Be equatorial disc\, which are a feature of m
 any HMXBs.\n\nhttps://events.iiap.res.in/event/399/
LOCATION:Auditorium
URL:https://events.iiap.res.in/event/399/
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