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Alexander Mustill. Profile picture.

Alexander Mustill

Researcher

Alexander Mustill. Profile picture.

Fast spectrophotometry of WD 1145+017

Author

  • Paula Izquierdo
  • Pablo Rodriguez-Gil
  • Boris T. Gänsicke
  • Alexander J. Mustill
  • Odette Toloza
  • Pier-Emmanuel Tremblay
  • Mark C Wyatt
  • Paul Chote
  • Siegfried Eggl
  • Jay Farihi
  • Detlev Koester
  • Wladimir Lyra
  • Christopher J. Manser
  • Thomas R. Marsh
  • Enric Pallé
  • Roberto Raddi
  • Dimitri Veras
  • Eva Villaver
  • Simon Portegies Zwart

Summary, in English

WD 1145+017 is currently the only white dwarf known to exhibit periodic transits of planetary debris as well as absorption lines from circumstellar gas. We present the first simultaneous fast optical spectrophotometry and broad-band photometry of the system, obtained with the Gran Telescopio Canarias (GTC) and the Liverpool Telescope, respectively. The observations spanned 5.5 h, somewhat longer than the 4.5-h orbital period of the debris. Dividing the GTC spectrophotometry into five wavelength bands reveals no significant colour differences, confirming grey transits in the optical. We argue that absorption by an optically thick structure is a plausible alternative explanation for the achromatic nature of the transits that can allow the presence of small-sized (~µm) particles. The longest (87 min) and deepest (50 per cent attenuation) transit recorded in our data exhibits a complex structure around minimum light that can be well modelled by multiple overlapping dust clouds. The strongest circumstellar absorption line, Fe II λ5169, significantly weakens during this transit, with its equivalent width reducing from a mean out-of-transit value of 2 to 1 Å in-transit, supporting spatial correlation between the circumstellar gas and dust. Finally, we made use of the Gaia Data Release 2 and archival photometry to determine the white dwarf parameters. Adopting a helium-dominated atmosphere containing traces of hydrogen and metals, and a reddening E(B - V) = 0.01 we find T_eff=15 020 ± 520 K, log g = 8.07 ± 0.07, corresponding to M_WD=0.63± 0.05 M☉ and a cooling age of 224 ± 30 Myr.

Department/s

  • Lund Observatory

Publishing year

2018-11-21

Language

English

Pages

703-714

Publication/Series

Monthly Notices of the Royal Astronomical Society

Volume

481

Issue

1

Document type

Journal article

Publisher

Oxford University Press

Topic

  • Astronomy, Astrophysics and Cosmology

Keywords

  • minor planets
  • asteroids: general
  • planets and satellites: physical evolution
  • planet-star interactions
  • planetary systems
  • white dwarfs
  • Astrophysics - Solar and Stellar Astrophysics
  • Astrophysics - Earth and Planetary Astrophysics

Status

Published

Project

  • IMPACT: Comets, asteroids and the habitability of planets
  • A unified picture of white dwarf planetary systems

ISBN/ISSN/Other

  • ISSN: 0035-8711