J/A+A/623/L12 sdOB star Feige 46 spectrum (Latour+, 2019)
Discovery of a second pulsating intermediate helium-enriched sdOB star.
Latour M., Green E.M., Fontaine G.
<Astron. Astrophys. 623, L12 (2019)>
=2019A&A...623L..12L 2019A&A...623L..12L (SIMBAD/NED BibCode)
ADC_Keywords: Stars, subdwarf ; Spectroscopy
Keywords: subdwarfs - stars: oscillations - stars: individual (Feige 46)
Abstract:
We present the discovery of long-period, low-amplitude, g-mode
pulsations in the intermediate He-rich hot subdwarf (sdOB) star Feige
46. So far, only one other He-enriched sdOB star (LS IV -14116) was
known to exhibit such pulsations. From our ground-based light curves
of Feige 46, we extracted five independent periodicities ranging from
2294s to 3400s. We fit our optical spectrum of the star with our
grid of non-local thermodynamic equilibrium (NLTE) model atmospheres
and derived the following atmospheric parameters: Teff=36120±230K,
logg=5.93±0.04, and log N(He)/N(H)=-0.32±0.03 (formal fitting
errors only). These parameters are very similar to those of
LS IV -14116 and place Feige 46 well outside of the instability strip
where the hydrogen-rich g-mode sdB pulsators are found. We used the
Gaia parallax and proper motion of Feige 46 to perform a kinematic
analysis of this star and found that it likely belongs to the Galactic
halo population. This is most certainly an intriguing and interesting
result given that LS IV -14116 is also a halo object.The mechanism
responsible for the pulsations in these two peculiar objects remains
unclear, but a possible scenario involves the epsilon-mechanism.
Although they are the only two members in their class of variable
stars, these pulsators appear to have more in common than just their
pulsation properties.
Description:
The star was observed multiple times with the 2.3m Bok telescope at
Steward Observatory on Kitt Peak between 2004 and 2011. The
observations were obtained with the B&C spectrograph using the
400mm-1 grating in first order and a 2.5-arcsec slit, resulting in a
wide wavelength coverage (3620-6900Å) and a rather low resolution
of 8.7Å. Our final spectrum with high S/N was constructed from five
median-filtered individual spectra that were first cross-correlated to
correct for possible variations in radial velocity.
Objects:
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RA (2000) DE Designation(s)
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11 37 26.37 +14 10 14.1 Feige 46 = EGGR 81
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
spectrum.dat 19 1188 Feige 46 spectrum
f46.fits 2880 5 Feige 46 spectrum in fits
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See also:
J/A+A/623/L11 : HR8799e K-band spectrum (Lacour+, 2019)
Byte-by-byte Description of file: spectrum.dat
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Bytes Format Units Label Explanations
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3- 6 I4 0.1nm lambda Wavelength
9- 19 E11.6 10-2W/m2/m Flux Flux (in erg/cm2/s/Å)
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Acknowledgements:
Marilyn Latour, marilyn.latour(at)uni-goettingen.de
(End) Patricia Vannier [CDS] 13-Mar-2019