J/A+A/630/A130 Co-added spectra of HD127493 and HZ44 (Dorsch+, 2019)
Heavy metals in intermediate He-rich hot subdwarfs:
the chemical composition of HZ44 and HD127493.
Dorsch M., Latour M., Heber U.
<Astron. Astrophys. 630, A130 (2019)>
=2019A&A...630A.130D 2019A&A...630A.130D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, subdwarf ; Spectroscopy
Keywords: stars: abundances - stars: atmospheres - stars: individual: HZ44 -
stars: individual: HD127493 - stars: evolution - stars: subdwarfs
Abstract:
Hot subluminous stars can be spectroscopically classified as subdwarf
B (sdB) and O (sdO) stars. While the latter are predominantly hydrogen
deficient, the former are mostly helium deficient. The atmospheres of
most sdOs are almost devoid of hydrogen, whereas a small group of hot
subdwarf stars of mixed H/He composition exists, showing extreme metal
abundance anomalies. Whether such intermediate helium-rich (iHe)
subdwarf stars provide an evolutionary link between the dominant
classes is an open question. The presence of strong Ge, Sn, and Pb
lines in the UV spectrum of HZ44 suggests a strong enrichment of heavy
elements in this iHe-sdO star and calls for a detailed quantitative
spectral analysis focusing on trans-iron elements. Non-LTE model
atmospheres and synthetic spectra calculated with TLUSTY/SYNSPEC were
combined with high-quality optical, ultraviolet (UV), and far-UV (FUV)
spectra of HZ44 and its hotter sibling HD127493 to determine their
atmospheric parameters and metal abundance patterns. By collecting
atomic data from the literature we succeeded in determining the
abundances of 29 metals in HZ44, including the trans-iron elements Ga,
Ge, As, Se, Zr, Sn, and Pb and providing upper limits for ten other
metals. This makes it the best-described hot subdwarf in terms of
chemical composition. For HD127493 the abundance of 15 metals,
including Ga, Ge, and Pb and upper limits for another 16 metals were
derived. Heavy elements turn out to be overabundant by one to four
orders of magnitude with respect to the Sun. Zr and Pb are among the
most enriched elements. The C, N, and O abundance for both stars can
be explained by the nucleosynthesis of hydrogen burning in the CNO
cycle along with the stars' helium enrichment. On the other hand, the
heavy-element anomalies are unlikely to be caused by nucleosynthesis.
Instead diffusion processes are evoked, with radiative levitation
overcoming gravitational settlement of the heavy elements.
Description:
We supply here the collection of co-added (and processed) spectra used
in our analysis of HD127493 and HZ44. Both stars have been observed
with several instruments. The datasets used to produce the supplied
spectra are listed in the following, along with notes about the
co-added spectra:
HD127493 - FEROS:
Datasets: ADP.2016-09-21T07:07:18.680, ADP.2016-09-21T07:07:18.736
ADP.2016-09-21T07:07:18.686
Columns: Wavelength (Angstrom), Normalized flux
Notes: The spectrum is normalized.
HD127493 - IUE (LWR):
Datasets: LWR03587HS, LWR04198HL, LWR06702HL, LWR07211HL
Columns: Wavelength (Angstroem), Flux (erg/cm2/s/Å),
Flux uncertainty (erg/cm2/s/Å)
Notes: The spectrum is based on single INES spectra which were
cross-correlated to about vrad=-9km/s and then co-added.
It should not be used as flux-calibrated or for radial
velocity measurements.
HD127493 - IUE (SWP):
Datasets: SWP04071HS, SWP04860HL, SWP07695HL, SWP08276HL
Columns: Wavelength (Angstroem), Flux (erg/cm2/s/Å),
Flux uncertainty (erg/cm2/s/Å)
Notes: The spectrum is based on single INES spectra which were
cross-correlated to about vrad=-9km/s and then co-added.
It should not be used as flux-calibrated or for radial
velocity measurements.
HD127493 - HST (GHRS E140M):
Datasets: Z2H60107T, Z2H60109T, Z2H6010BT, Z2H6010DT, Z2H6010FT,
Z2H6010HT, Z2H6010JT, Z2H6010LT, Z2H6010OT, Z2H6010QT
Columns: Wavelength (Angstrom), Flux (erg/cm2/s/Å),
Flux uncertainty (erg/cm2/s/Å)
Notes: The spectrum is cross-correlated to about vrad=-2.5km/s.
It should not be used as flux-calibrated or for radial
velocity measurements.
HZ44 - HIRES:
Datasets: HI.20050810.20686, HI.20050810.21381, HI.20050812.21565,
HI.20070504.38715, HI.20160203.58141, HI.20160401.55323
Columns: Wavelength (Angstroem), Flux (arbitrary units)
Notes: For each observation, the single orders were normalized by hand.
The observations were then cross-correlated and co-added using
the respective uncertainties. The co-added spectrum was
normalized to match the final synthetic spectrum of HZ44.
It can not be used to derive atmospheric parameters and several
blue HeI lines that are missing in the model are missing.
It should only be used to derive abundances from narrow metal lines.
HZ44 - ISIS:
Columns: Wavelength (Angstroem), Flux (erg/cm2/s/Å)
Notes: The spectrum covers the 3700 to 5260 Angstrom range at a
resolution of about 1.5 Angstrom.
HZ44 - IUE (SWP):
Datasets: SWP16294HL, SWP17350HL
Columns: Wavelength (Angstroem), Flux (erg/cm2/s/Å)
Notes: The spectrum should not be used to derive radial velocities.
HZ44 - FUSE (MDRS):
Dataset: p3020401000
Columns: Wavelength (Angstroem), Flux (erg/cm2/s/Å)
Notes: The spectrum should not be used to derive radial velocities.
All datasets listed are available online. Please refer to the
respective archives for more detailed information.
Objects:
----------------------------------------------------
RA (2000) DE Designation(s)
----------------------------------------------------
14 32 21.49 -22 39 25.65 HD 127493 = BD-22 3804
13 23 35.26 +36 07 59.55 HZ 44 = TYC 2541-4-1
----------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
hd_feros.dat 51 87482 HD 127493 FEROS spectrum
hd_ghrs.dat 77 18703 HD 127493 HST GHRS E140M spectrum
hdiuel.dat 77 23015 HD 127493 IUE LWR spectrum
hdiues.dat 77 20619 HD 127493 IUE SWP spectrum
hz_fuse.dat 77 21871 HZ 44 FUSE MDRS spectrum
hz_hires.dat 51 202170 HZ 44 HIRES spectrum
hz_isis.dat 51 3881 HZ 44 ISIS spectrum
hziues.dat 77 15954 HZ 44 IUE SWP spectrum
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Byte-by-byte Description of file: hd_feros.dat
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Bytes Format Units Label Explanations
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2- 25 E24.18 0.1nm lambda Wavelength
27- 51 E25.18 --- Flux Normalized flux
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Byte-by-byte Description of file: hz_hires.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
2- 25 E24.18 0.1nm lambda Wavelength
27- 51 E25.18 --- Flux Flux in arbitrary units
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Byte-by-byte Description of file: hz_isis.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
2- 25 E24.18 0.1nm lambda Wavelength
27- 51 E25.18 10-2W/m2/nm Flux Flux
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Byte-by-byte Description of file: *ghrs.dat *iue*.dat *fuse.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
2- 25 E24.18 0.1nm lambda Wavelength
27- 51 E25.18 10-2W/m2/nm Flux Flux (in erg/cm2/s/Å)
54- 77 E24.18 10-2W/m2/nm e_Flux Flux uncertainty (in erg/cm2/s/Å)
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Acknowledgements:
Matti Dorsch, matti.dorsch(at)fau.de
(End) Patricia Vannier [CDS] 07-Aug-2019