J/ApJ/845/171 Rapidly pulsating sdB stars search with GALEX (Boudreaux+, 2017)
A search for rapidly pulsating hot subdwarf stars in the GALEX survey.
Boudreaux T.M., Barlow B.N., Fleming S.W., Soto A.V., Million C.,
Reichart D.E., Haislip J.B., Linder T.R., Moore J.P.
<Astrophys. J., 845, 171 (2017)>
=2017ApJ...845..171B 2017ApJ...845..171B
ADC_Keywords: Stars, subdwarf; Ultraviolet; Stars, variable
Keywords: stars: oscillations (including pulsations)
Abstract:
NASA's Galaxy Evolution Explorer (GALEX) provided near- and far-UV
observations for approximately 77% of the sky over a 10-year period;
however, the data reduction pipeline initially only released single
NUV and FUV images to the community. The recently released Python
module gPhoton changes this, allowing calibrated time-series aperture
photometry to be extracted easily from the raw GALEX data set. Here we
use gPhoton to generate light curves for all hot subdwarf B (sdB)
stars that were observed by GALEX, with the intention of identifying
short-period, p-mode pulsations. We find that the spacecraft's short
visit durations, uneven gaps between visits, and dither pattern make
the detection of hot subdwarf pulsations difficult. Nonetheless, we
detect UV variations in four previously known pulsating targets and
report their UV pulsation amplitudes and frequencies. Additionally, we
find that several other sdB targets not previously known to vary show
promising signals in their periodograms. Using optical follow-up
photometry with the Skynet Robotic Telescope Network, we confirm
p-mode pulsations in one of these targets, LAMOST J082517.99+113106.3,
and report it as the most recent addition to the sdBVr class of
variable stars.
Description:
Here we present a search for short-period hot subdwarf B (sdB)
pulsations in the archived GALEX data set using gPhoton
(Million+ 2016ApJ...833..292M 2016ApJ...833..292M). An initial sample of 5613 hot
subdwarfs (Geier+ 2017, J/A+A/600/A50), which represents a good
approximation of all cataloged hot subdwarf stars, was down-selected
based on magnitudes, coordinates, and total exposure time available in
the gPhoton database, described fully in Section 2. These selection
criteria yielded 1881 targets upon which we focused our investigation.
Calibrated light curves with time bins of 30s were generated for each
target using gPhoton.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
sdb.dat 26 1444 List of the 1444 targets; table added by CDS
table1.dat 84 4150 Results from data analysis for 1444 stars
table2.dat 46 13 Single GALEX visit for the each of the 13 known
sdBVr targets
table3.dat 40 5 Known pulsating sdBVr stars with GALEX-detected NUV
variations
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See also:
II/312 : GALEX-DR5 (GR5) sources from AIS and MIS (Bianchi+ 2011)
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
J/AJ/138/606 : Hot subdwarf stars in rejected PG catalog (Wade+, 2009)
J/A+A/513/A6 : NOT survey of subdwarf B stars (Ostensen+, 2010)
J/MNRAS/427/2180 : GALEX survey subdwarf atmospheric parameters (Nemeth+, 2012)
J/ApJ/764/25 : FUSE spectra analysis of hot subdwarf stars (Jenkins, 2013)
J/A+A/569/A15 : KIC 10553698A asteroseismology (Ostensen+, 2014)
J/MNRAS/457/3396 : New hot subdwarf stars (Perez-Fernandez+, 2016)
J/A+A/600/A50 : Catalog of hot subdwarf stars (Geier+, 2017)
Byte-by-byte Description of file: sdb.dat
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Bytes Format Units Label Explanations
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1- 26 A26 --- Name Target name (G1)
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 26 A26 --- Name Target name (G1)
28- 30 I3 --- Nv [1/119] Sequential visit number
32- 42 F11.5 d MJD Visit Start Time, JD-2400000.5 (G2)
44- 55 F12.7 s Dur [723/1697] Visit duration
57- 65 F9.1 --- <Noise> [-71300/1530690] Mean noise,
parts per thousand (G3)
67- 72 F6.1 --- Peak [5.4/3753.6] Max peak amplitude,
parts per thousand (G3)
74- 78 I5 uHz Freq [59/16667] Frequency of maximum peak (G3)
80- 84 F5.1 --- Sigma [-9.2/594] Sigma metric
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Name Target name (G1)
19- 19 A1 --- sdBVr [* ] *: sdBVr star identified in this study
21- 32 F12.6 d MJD Visit Start Time, JD-2400000.5 (G2)
34- 41 F8.3 s Dur [887/1694] Visit duration
43- 46 F4.1 --- <Noise> [2.8/71.5] Mean noise, parts per thousand (G3)
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Name Target name (G1)
19- 19 I1 --- Nv [1/2] Sequential visit number
21- 22 I2 --- NUVamp [12/31] GALEX NUV amplitude, parts per thousand
24- 24 I1 --- e_NUVamp [2/4] Uncertainty in NUVamp, parts per thousand
26- 29 I4 uHz Freq [2800/7880] Frequency of maximum peak (G3)
31- 33 I3 uHz e_Freq [32/121] Uncertainty in Freq
35- 40 F6.2 s Per [126/358] Period
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Global notes:
Note (G1): From Geier et al. (2017, J/A+A/600/A50)
Note (G2): Start Time refers to the beginning of the GALEX visit, where
MJD=JD-2400000.5.
Note (G3): Mean noise, maximum peak, and frequency of maximum peak are all
reported after pre-whitening for the dither pattern and the first
harmonic of the dither pattern.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 10-Apr-2018