J/AJ/169/82 Radial velocities of AW UMA second component (Rucinski, 2025)
Lessons from the high-resolution spectroscopy of AW UMa and ε CrA:
Is the Lucy model valid?
Rucinski S.M.
<Astron. J., 169, 82 (2025)>
=2025AJ....169...82R 2025AJ....169...82R
ADC_Keywords: Radial velocities; Stars, double and multiple; Spectroscopy;
Optical
Keywords: Contact binary stars
Abstract:
A re-examination of high-resolution spectral monitoring of the
W UMa-type binaries AW UMa and ε CrA casts doubt on the widely
utilized L. B. Lucy model of contact binaries. The detection of the
very faint profile of the secondary component in AW UMa leads to a new
spectroscopic determination of the mass ratio, qsp=0.092±0.007,
which is close to the previous, medium-resolution spectroscopic result
of T. Pribulla & S. M. Rucinski, qsp=0.101±0.006, and remains
substantially different from a cluster of generally accepted
photometric results by several authors, concentrated around
qph=0.080±0.005. A survey of binaries with the best-determined
values of the mass ratio shows a common tendency for qph<qsp. The
tendency for systematically smaller values of qph may result from
the overfilling of the primary lobe and underfilling of the secondary
lobe relative to the Roche model geometry, as predicted by the
K. Stepien model. Despite the observed moderate inter-systemic
velocities, the photometric Lucy model may remain useful in providing
approximate, though biased, results for the mass ratio. A complicating
factor in detailed spectral analysis may be the occurrence of Enhanced
Spectral-line Perturbations (ESPs) projected over the secondary
profiles, appearing in different numbers in the two studied binaries.
The ESPs are tentatively identified within the Stepien model as
collision fronts or fountains of primary-component gas from the
circumbinary, energy-carrying flow.
Description:
This paper brings a comparison and rediscussion of the results from
Rucinski+2015 (J/AJ/149/49) and Rucinski 2020 (J/AJ/160/104).
The observations of AW UMa were obtained on the nights of
2011 March 11-13 using the Canada-France-Hawaii Telescope (CFHT) and
its Espadons spectrograph (370-1,050nm) working in the
spectro-polarimetric mode. The nominal spectral resolving power was
R∼68000. In total, 584 individual observations of AW UMa were
obtained. The exposure times were 90s and the median spacing between
observations was 125s.
Observations of ε CrA were made in the service mode with the
CHIRON spectrograph (506.5-529.2nm) on the Cerro Tololo Inter-American
Observatory Small and Moderate Aperture Research Telescope System
(CTIO/SMARTS) 1.5m telescope on eight nights between 2018 July 12 and 29.
361 exposures of 450s were taken using the slicer setup, which
provides a spectral resolving power of R=80000.
Objects:
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RA (2000) DE Designation(s)
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11 30 04.31 +29 57 52.6 AW UMa = 2MASS J11300431+2957530
18 58 43.38 -37 06 26.3 epsilon CrA = 2MASS J18584339-3706263
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 21 118 AW UMa: Radial velocities of the secondary-component
profile edges
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See also:
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
J/AJ/130/767 : Radial velocity studies of close binary stars (Rucinski+, 2005)
J/ApJ/629/1055 : Evolution of close binary systems (Yakut+, 2005)
J/AJ/132/769 : Radial velocities of 10 close binaries (Pribulla+, 2006)
J/AJ/132/1539 : Radial velocities of southern close binaries (Rucinski+, 2006)
J/A+A/450/681 : Companions to close spectroscopic binaries (Tokovinin+, 2006)
J/AJ/133/1977 : Radial velocities of 10 close binaries (Pribulla+, 2007)
J/AJ/134/2353 : Observations of contact binaries (Rucinski+, 2007)
J/AJ/136/586 : Radial velocities of 10 close binaries (Rucinski+, 2008)
J/AJ/137/3655 : Radial velocities of 8 close binaries (Pribulla+, 2009)
J/AJ/146/70 : Spectroscopy of W UMa-type binary stars (Rucinski+, 2013)
J/AJ/149/49 : Radial velocities of AW UMa (Rucinski+, 2015)
J/AcA/65/39 : OGLE Gal. Bulge ultra-short-period binaries (Soszynski+, 2015)
J/AJ/160/104 : Ε CrA components radial & orbit. veloc. (Rucinski, 2020)
J/ApJS/254/10 : Compilation of W UMa stars (Latkovic+, 2021)
J/AJ/164/202 : Extremely Low Mass Ratio Contact Binaries I. 10 syst. (Li+,2022)
J/A+A/672/A176 : Mass-ratio distribution of contact binary stars (Pesta+, 2023)
J/A+A/687/A259 : Altair light curves (Rieutord+, 2024)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 F5.3 --- Phase [0.6/5.7] Orbital phase (1)
7- 13 F7.2 km/s RVel1 [-409/212.1] Secondary component profile's first
edge heliocentric radial velocity
15- 21 F7.2 km/s RVel2 [-260/401.7] Secondary component profile's
second edge heliocentric radial velocity
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Note (1): The time expressed in orbital phase counted continuously from the
assumed initial epoch HJD=2,455,631.6498 and P=0.43872420day
(as defined in Rucinski+2015, J/AJ/149/49).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Robin Leichtnam [CDS] 21-Nov-2025