J/A+A/567/A30 HERMES spectra of IP Eri (Merle+, 2014)
IP Eri: A surprising long-period binary system hosting a He white dwarf.
Merle T., Jorissen A., Masseron T., Van Eck S., Siess L., Van Winckel H.
<Astron. Astrophys. 567, A30 (2014)>
=2014A&A...567A..30M 2014A&A...567A..30M
ADC_Keywords: Binaries, spectroscopic ; Abundances ; Spectroscopy
Keywords: stars: abundances - binaries: spectroscopic - stars: evolution -
stars: individual: IP Eridani - subdwarfs - white dwarfs
Abstract:
We determine the orbital elements for the K0 IV + white dwarf (WD)
system IP Eri, which appears to have a surprisingly long period of
1071d and a significant eccentricity of 0.25. Previous spectroscopic
analyses of the WD, based on a distance of 101pc inferred from its
Hipparcos parallax, yielded a mass of only 0.43M☉, implying it
to be a helium-core WD. The orbital properties of IP∼Eri are similar
to those of the newly discovered long-period subdwarf B star (sdB)
binaries, which involve stars with He-burning cores surrounded by
extremely thin H envelopes, and are therefore close relatives to He
WDs. We performed a spectroscopic analysis of high-resolution spectra
from the HERMES/Mercator spectrograph and concluded that the
atmospheric parameters of the K0 component are Teff=4960K, logg=3.3,
[Fe/H]=0.09 and vt=1.5km/s. The detailed abundance analysis focuses on
C, N, O abundances, carbon isotopic ratio, light (Na, Mg, Al, Si, Ca,
Ti) and s-process (Sr, Y, Zr, Ba, La, Ce, Nd) elements. We conclude
that IP∼Eri abundances agree with those of normal field stars of the
same metallicity. The long period and non-null eccentricity indicate
that this system cannot be the end product of a common-envelope phase;
it calls instead for another less catastrophic binary-evolution
channel presented in detail in a companion paper.
Description:
Two HERMES/Mercator high-resolution FITS spectra used in the
determination of atmospheric parameters and detailed abundance
analysis are available. Those spectra are not normalized, with removal
of cosmics and not corrected from radial velocity.
Objects:
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RA (2000) DE Designation(s)
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02 54 38.83 -05 19 50.9 IP Eri = HD 18131
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 100 2 List of FITS spectra
sp/* . 2 Individual FITS spectra
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 7 F7.2 0.1nm lam.min Lower value of wavelength interval
9- 15 F7.2 0.1nm lam.max Upper value of wavelength interval
17- 24 F8.6 0.1nm dlambda Wavelength resolution
26- 31 I6 --- Nx Number of lines
33- 36 I4 Kibyte size [2661] Size of FITS file
38- 49 F12.4 d BJD Barycentric date of mid-observation
51- 61 A11 --- FileName Name of the file containing the spectrum in
subdirectory sp
63-100 A38 --- Title Title of the file
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Acknowledgements:
Thibault Merle, tmerle(at)ulb.ac.be
(End) Thibault Merle [IAA, ULB], Patricia Vannier [CDS] 19-May-2014