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SUMMARY:The TOI-561 system: a low density ultra-short period super-Earth a
 nd three mini-Neptunes - Gaia Lacedelli (Padova)
DTSTART:20201020T120000Z
DTEND:20201020T130000Z
UID:TALK152632@talks.cam.ac.uk
CONTACT:Dr Annelies Mortier
DESCRIPTION:Multi-planet systems offer a unique opportunity for comparativ
 e exoplanetology\, having originated from the same protoplanetary disk and
  evolved in the same environment.  This makes them appealing targets to te
 st theoretical planetary formation and evolution scenarios.\nIn this semin
 ar I will describe the multi-planet system orbiting the old\, metal-poor s
 tar TOI-561. The system has been characterised using TESS photometry and h
 igh precision HARPS-N radial velocity (RV) data. We  found  that  TOI-561 
  hosts  four  transiting  planets\,  namely  an  ultra-short period (USP) 
 super-Earth and three mini-Neptunes.  In fact\, after the identification o
 f three transiting candidates by TESS\, we discovered two additional exter
 nal planets based on RV analysis. We confirmed and characterised the two i
 nner TESS candidates\, but we showed that the third candidate can not be c
 onfirmed by RVs\, and would make the system dynamically unstable. We demon
 strated that the two transits initially associated with this candidate are
  instead due to single transits of the two additional planets discovered i
 n the RV data\, that also have a predicted strong\, anti-correlated transi
 t time variation signal. With a density of ∼3 g cm−3\, which is consis
 tent with a water-dominated composition\, the inner super-Earth is the low
 est density USP planet known to date.
LOCATION:ONLINE - Details to be sent by email
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