Skip to main content

Mark Hollands

I am a postdoc in the Warwick Astronomy and Astrophysics group. I am currently working with Pier-Emmanuel Tremblay on white dwarfs in the Gaia survey. My academic CV can be found here.

Research

I study white dwarfs, the ultra-dense remains of burnt out stars—in particular I study those that have traces of metals in their atmospheres. The intense gravitaional fields of white dwarfs cause elements heavier than helium to sink out of the atmosphere in relatively short-order. Therefore the detection of metals in the photospheres of >25% of white dwarfs indicates this material must have been accreted externally.

The detection of debris disks (infrared excesses) at a number of metal-rich white dwarfs, plus the recent observation of transists from a disintegrating planetesimal at WD1145+017 confirm the hypothesis that these metals come from rocky bodies such as asteroids.

Dusty white dwarf

Image Credit: Nasa/JPL-Caltech

By analysing white dwarf atmospheres, we can therefore directly measure the composition of rocky material formed in other star systems! Furthermore, by determining white dwarf ages, we can learn about the evolution of remnant planetary systems over billions of years. For the systems I study this means looking back into the Milky Way's past, but for the Solar System correspondsas to looking forwards as the Sun will become a white dwarf in ~6 billion years.

I am also interested in magnetic white dwarfs, including their origin, evolution, and the field geometries of individual objects.

Publications I have been involved with


Talks Given

  • Revisiting the white dwarf local sample in the era of Gaia - presented at the 21st European white dwarf workshop (Austin, 2018)
  • Remnant planetary systems around the oldest white dwarfs - Seminar (Caltech, 2017)
  • Chemistry and evolution of the oldest white dwarf planetary systems - presented at Astrochemsitry VII IAU symposium 332 (Puerto Varas, 2017)
  • Chemistry and evolution of the oldest white dwarf planetary systems - presented at Planetary Systems Beyond the Main Sequence II (Technion, 2017)
  • Chemistry and evolution of the oldest white dwarf planetary systems - Seminar (Institute of Astronomy, Cambridge, 2016)
  • A large sample of cool, strongly-polluted DZ white dwarfs - presented at the 20th European white dwarf workshop (Warwick, 2016)
  • Metals as tracers of magnetism in old white dwarfs - presented at the Stellar End Products meeting (ESO Garching, 2015)
  • Planetary systems as tracers of magnetism in old white dwarfs - presented at the workshop: Mysteries of the Suns magnetic field III: Understanding stellar activity (Warwick, 2015)
  • Ancient planetary systems around white dwarfs - presented at the 19th European white dwarf workshop (Montreal, 2014)

myself

Write to:

Mark Hollands

Department of Physics,
University of Warwick,
Coventry CV4 7AL
UK
 

Contact details:

E-Mail: M.Hollands AT warwick.ac.uk