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SUMMARY:Helium Stars\, Heavy Metals\, High Velocities and Explosions  - S
 imon Jeffery (Armagh)
DTSTART:20190131T160000Z
DTEND:20190131T170000Z
UID:TALK118075@talks.cam.ac.uk
CONTACT:28811
DESCRIPTION:The term "hot subdwarf" refers to stars which are smaller than
 \nhydrogen-burning main-sequence stars and larger than white dwarfs. It\ni
 ncludes stars in several different advanced stages of evolution. Most have
 \nsurfaces severely depleted in either hydrogen or helium\; some explanati
 on\nexists for most of these. My talk will review the general properties o
 f\nhelium-poor and helium-rich subdwarfs and contemporary models for their
 \norigins. \n\nI will introduce the extremely rare "intermediate helium s
 ubdwarfs"\, which\npose significant challenges. \nSeveral show extraordin
 ary surface abundances of the heavy metals zirconium\,\nyttrium\, strontiu
 m\, germanium and lead. All of these heavy-metal stars are\non high-energy
  galactic orbits. Two pulsate in modes which\, until now\, were\nthought t
 o be impossible. Now\, new theoretical results force us toward new\nquesti
 ons and new ideas about the origin of these stars. \n
LOCATION:Sackler Lecture Theatre\, IoA (tea at 3:30 pm)
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