A disintegrating minor planet transiting a white dwarf.
Most stars become white dwarfs after they have exhausted their nuclear fuel (the Sun will be one such). Between one-quarter and one-half of white dwarfs have elements heavier than helium in their atmospheres, even though these elements ought to sink rapidly into the stellar interiors (unless they are occasionally replenished). The abundance ratios of heavy elements in the atmospheres of white dwarfs are similar to the ratios in rocky bodies in the Solar System. This fact, together with the existence of warm, dusty debris disks surrounding about four per cent of white dwarfs, suggests that rocky debris from the planetary systems of white-dwarf progenitors occasionally pollutes the atmospheres of the stars. The total accreted mass of this debris is sometimes comparable to the mass of large asteroids in the Solar System. However, rocky, disintegrating bodies around a white dwarf have not yet been observed. Here we report observations of a white dwarf--WD 1145+017--being transited by at least one, and probably several, disintegrating planetesimals, with periods ranging from 4.5 hours to 4.9 hours. The strongest transit signals occur every 4.5 hours and exhibit varying depths (blocking up to 40 per cent of the star's brightness) and asymmetric profiles, indicative of a small object with a cometary tail of dusty effluent material. The star has a dusty debris disk, and the star's spectrum shows prominent lines from heavy elements such as magnesium, aluminium, silicon, calcium, iron, and nickel. This system provides further evidence that the pollution of white dwarfs by heavy elements might originate from disrupted rocky bodies such as asteroids and minor planets.
Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA.
Andrew
A
Vanderburg
Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA.
John Asher
JA
Johnson
Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Saul
S
Rappaport
Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA.
Allyson
A
Bieryla
Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA.
Jonathan
J
Irwin
Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA.
John Arban
JA
Lewis
Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA.|Department of Astronomy, Columbia University, New York, New York 10027, USA.
David
D
Kipping
Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA.
Warren R
WR
Brown
Institut de Recherche sur les Exoplanètes, Départment de Physique, Université de Montréal, Montréal, Quebec H3C 3J7, Canada.
Patrick
P
Dufour
NASA Exoplanet Science Institute, California Institute of Technology, Pasadena, California 91125, USA.
David R
DR
Ciardi
Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA.|Department of Physics, University of Oxford, Oxford OX1 3RH, UK.
Ruth
R
Angus
Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA.
Laura
L
Schaefer
Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA.
David W
DW
Latham
Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA.
David
D
Charbonneau
NASA Exoplanet Science Institute, California Institute of Technology, Pasadena, California 91125, USA.
Charles
C
Beichman
Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA.
Jason
J
Eastman
Department of Physics and Astronomy, University of Montana, Missoula, Montana 59812, USA.
Nate
N
McCrady
School of Physics and Australian Centre for Astrobiology, University of New South Wales, Sydney, New South Wales 2052, Australia.
Robert A
RA
Wittenmyer
Department of Astronomy and Astrophysics and Center for Exoplanets and Habitable Worlds, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Jason T
JT
Wright