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SUMMARY:Disc evolution in young intermediate-mass stars - Daniela Iglesias
  Vallejo (Leeds)
DTSTART:20240213T130000Z
DTEND:20240213T140000Z
UID:TALK210826@talks.cam.ac.uk
CONTACT:Dr Emily Sandford
DESCRIPTION:Planets are born from circumstellar discs and the evolution of
  these discs determines the final architecture of planetary systems. The s
 tellar mass range between 1.5 and 3.5 solar masses presents a particularly
  interesting circumstellar disc evolution\; most notably\, it is dominated
  by the EUV/FUV photoevaporation regime on the pre-main sequence\, it cont
 ains the majority of gaseous debris discs\, and it also shows the highest 
 giant planet frequency. In our recent spectroscopic VLT/X-Shooter survey (
 UV to nIR)\, combined with WISE data (nIR to mIR)\, we identified 135 pre-
 main sequence (PMS) intermediate mass stars (IMSs) in the Southern sky. Th
 is is the first unbiased sample of IMSs in the PMS\, allowing a study of d
 isc evolution. Our sample\, encompassing protoplanetary and debris discs\,
  also revealed a significant number of discs between these two evolutionar
 y stages.  We find that the IR excess evolution of IMSs differs from that 
 seen for low-mass stars (LMSs)\, exemplified by samples drawn from nearby 
 star forming regions. We observe that\, in IMSs\, the inner disc regions a
 re vacated in their entirety\, in contrast to the LMSs where we note a mor
 e gradual inside-out dissipation. We also investigated the presence of gas
  absorption features in our sample via optical high-resolution spectroscop
 y to identify gas-bearing debris discs. This requires detailed comparisons
  to spectra of nearby stars to eliminate objects with foreground cloud abs
 orption as cause of the absorption features. In particular\, we apply this
  effective method to one such disc\, eta Tel\, discarding the earlier clai
 m of disc wind as the origin for the absorption features. Finally\, we dis
 cuss our several ongoing and future surveys investigating the nature of ci
 rcumstellar discs around IMSs.
LOCATION:Ryle seminar room + ONLINE - Details to be sent by email
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