J/A+A/551/L4 SB 290 radial velocity curve (Geier+, 2013)
The subdwarf B star SB 290 - a fast rotator on the extreme horizontal branch.
Geier S., Heber U., Heuser C., Classen L., O'Toole S.J., Edelmann H.
<Astron. Astrophys., 551, L4-4 (2013)>
=2013A&A...551L...4G 2013A&A...551L...4G
ADC_Keywords: Binaries, spectroscopic ; Radial velocities
Keywords: binaries: spectroscopic - subdwarfs - stars: rotation
Abstract:
Hot subdwarf B stars (sdBs) are evolved core helium-burning stars with
very thin hydrogen envelopes. To form an sdB, the progenitor has to
lose almost all of its hydrogen envelope right at the tip of the red
giant branch. In close binary systems, mass transfer to the companion
provides the extraordinary mass loss required for their formation.
However, apparently single sdBs exist as well, and their formation has
been unclear for decades. The merger of helium white dwarfs leading to
an ignition of core helium-burning or the merger of a helium core and
a low-mass star during the common envelope phase have been proposed.
Here we report the discovery of SB 290 as the first apparently
single, fast-rotating sdB star located on the extreme horizontal
branch, indicating that those stars may form from mergers.
Description:
Thanks to its brightness, SB 290 has been monitored by planetary
transit surveys. An excellent white light curve taken from May 2006 to
December 2007 was downloaded from the SuperWASP Public archive. The
light curve consists of no fewer than 10192 single measurements.
Time-resolved medium-resolution spectroscopy (R~=4000,
λ=3500-5100Å) was obtained in the course of the MUCHFUSS
project. One dataset consisting of 19 spectra was taken with the ISIS
spectrograph mounted at the WHT in August 2009.
Objects:
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RA (2000) DE Designation(s)
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00 42 58.31 -38 07 37.3 SB 290 = CD-38 222
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 67 46 Radial velocities of SB 290
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 13 F13.5 d HJD Mid-HJD date of observation
14 A1 --- n_HJD [a] a: the observing time could only be
reconstructed to within this night
16- 20 F5.1 km/s RV Radial velocity
22- 24 F3.1 km/s e_RV rms uncertainty on RV
26- 65 A40 --- Inst Instrument or reference
67 A1 --- n_Inst [*] Note (1)
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Note (1): Due to the highly variable signal-to-noise ratio of the single
spectra, consecutive spectra have been coadded until the quality was
sufficient to measure the RV to within about the given uncertainty.
In this way, 20 RV epochs have been obtained.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 26-Aug-2013