J/MNRAS/449/574 Circumstellar discs at white dwarfs (Rocchetto+, 2015)
The frequency and infrared brightness of circumstellar discs at white dwarfs.
Rocchetto M., Farihi J., Gansicke B.T., Bergfors C.
<Mon. Not. R. Astron. Soc., 449, 574-587 (2015)>
=2015MNRAS.449..574R 2015MNRAS.449..574R (SIMBAD/NED BibCode)
ADC_Keywords: Stars, white dwarf ; Stars, masses ; Photometry, millimetric/submm
Keywords: stars: abundances - circumstellar matter - planetary systems -
white dwarfs
Abstract:
White dwarfs whose atmospheres are polluted by terrestrial-like
planetary debris have become a powerful and unique tool to study
evolved planetary systems. This paper presents results for an unbiased
Spitzer Infrared Array Camera search for circumstellar dust orbiting a
homogeneous and well-defined sample of 134 single white dwarfs. The
stars were selected without regard to atmospheric metal content but
were chosen to have (1) hydrogen-rich atmospheres, (2)
17000<Teff<25000K and correspondingly young post-main-sequence ages of
15-270Myr, and (3) sufficient far-ultraviolet brightness for a
corresponding Hubble Space Telescope COS snapshot. Five white dwarfs
were found to host an infrared bright dust disc, three previously
known, and two reported here for the first time, yielding a nominal
3.7+2.4-1.0 percent of white dwarfs in this post-main-sequence age
range with detectable circumstellar dust. Remarkably, the
complementary Hubble observations indicate that a fraction of 27
percent show metals in their photosphere that can only be explained
with ongoing accretion from circumstellar material, indicating that
nearly 90 percent of discs escape detection in the infrared, likely
due to small emitting surface area. This paper also presents the
distribution of disc fractional luminosity as a function of cooling
age for all known dusty white dwarfs, suggesting possible disc
evolution scenarios and indicating an undetected population of
circumstellar discs.
Description:
A total of 100 sample stars were observed between 2012 May and October
in the 3.6 and 4.5um bandpasses using the Infrared Array Camera
(IRAC) on-board the Spitzer Space Telescope s part of Programme 80149.
Independent JHKs photometry was also obtained for five targets. The
stars were observed in 2011 October with LIRIS at the William Herschel
Telescope (WHT) and in 2011 August with SOFI at the New Technology
Telescope (NTT), with exposure times of 30, 15, and 10s at J, H, and
Ks, respectively.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 77 140 Stellar parameters and flux determinations for
the science targets
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See also:
http://www.astronomy.villanova.edu/WDcatalog : Villanova white dwarf catalog
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- WD WD name (HHMM+DDd.N)
13- 17 I5 K Teff Effective temperature
19- 22 F4.2 [cm/s2] logg Surface gravity
24- 28 F5.2 mag Vmag ?=- V magnitude
30- 33 F4.2 Msun Mwd ?=- WD mass
35- 38 F4.2 Msun Mms ?=- Main-sequence progenitor mass
40- 43 F4.2 [yr] log(tcool) Cooling time
45- 48 I4 uJy F3.6um ?=- Flux at 3.6um
50- 52 I3 uJy e_F3.6um ? rms uncertainty on F3.6um
54- 57 I4 uJy F4.5um ?=- Flux at 4.5um
59- 61 I3 uJy e_F4.5um ? rms uncertainty on F4.5um
63- 66 I4 uJy F5.7um ?=- Flux at 5.7um
68- 69 I2 uJy e_F5.7um ? rms uncertainty on F5.7um
71- 74 I4 uJy F7.9um ?=- Flux at 7.9um
76- 77 I2 uJy e_F7.9um ? rms uncertainty on F7.9um
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 10-Nov-2015