J/A+A/696/A82 Ellipsoidal and rotational red giant binaries (Navarrete+, 2025)
A comprehensive Gaia view of ellipsoidal and rotational red giant binaries.
Navarrete C., Recio-Blanco A., de Laverny P., Escorza A.
<Astron. Astrophys. 696, A82 (2025)>
=2025A&A...696A..82N 2025A&A...696A..82N (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, spectroscopic; Stars, late-type ; Optical ;
Stars, masses ; Effective temperatures
Keywords: binaries: close - binaries: general - binaries: spectroscopic -
stars: fundamental parameters - stars: late-type
Abstract:
The latest Gaia Focused Product Release (FPR) provided variability
information for ∼1000 long-period red giant binaries, including almost
∼700 ellipsoidal binary candidates, the largest sample to date of this
binary type having both photometric and spectroscopic time series
observations. We aim to characterise physically (luminosity, mass,
radius) and chemo-dynamically (metallicity, [alpha/Fe], Galactic
velocities) the population of long-period red giant ellipsoidal binary
candidates, and a subsample of rotational variable candidates, from
Gaia FPR, combining Gaia astrometry, photometry and spectroscopy
observations. We cross-matched the Gaia DR3 measurements (positions,
velocities, atmospheric parameters, chemical abundances) with the
catalogue of long-period red giant candidates from the Gaia FPR,
having photometric and radial velocity variability information.
Combined with the photo-geometric distances, the extinction,
bolometric magnitude, luminosity, spectroscopic radius and mass were
estimated. The accuracy of this method was tested for similar samples
in the literature, including red giant binaries having asteroseismic
determination of their physical parameters. Ellipsoidal variables are
characterized to be low to intermediate-mass stars
(0.6≤M1≤5.0M☉), with radii as large as the Roche lobe radius
of the binary. Eccentricities tend to be lower for primary stars with
smaller radii, as the expected result of tidal circularization.
Combined with the orbital properties, estimates for the minimum mass
of the companion agree with the scenario of a low-mass compact object
as the secondary star. There are at least 14 ellipsoidal binaries with
orbital periods and masses of the two stars compatible with model
predictions for Type Ia SN progenitors. For the rotational variables,
their orbital periods, enhanced chromospheric activity, smaller radii
and low mass (M1≤1.5M☉) point to a different type of binaries
than the original ellipsoidal sample. The Galactic velocities indicate
that ellipsoidal variables are found both in the Galactic disk and
halo, while rotational variables are predominantly concentrated in the
Galactic disk. The velocity dispersion is much higher in ellipsoidal
than in rotational binaries, probably indicating older/younger
dynamical ages. The enhanced [alpha/Fe] abundances for some of the
ellipsoidal binaries, having M1≥1.0M☉_, resemble the population
of young alpha-rich binaries in the thick disk. An episode of mass
transfer in those systems may have produced the enhanced alpha
abundances, and the enhanced [Ce/Fe] abundances reported in a few
ellipsoidal binaries. Luminosities, radii and masses were derived for
243 ellipsoidal and 39 rotational binary candidates, the largest
Galactic sample of these variables, having chemo-dynamical and
physical parametrization. Based on their mean chemo-dynamical
properties and stellar parameters, these binaries can be considered as
two manifestations of the same phenomena, a close binary with a giant
primary, instead of two independent, unrelated binary types. Detailed
future analysis of individual sources will provide insights into the
history and future evolution of these binaries.
Description:
Physical parameters of the primary star for rotational and ellipsoidal red
giant binary systems. For each binary, the period, effective temperature,
surface gravity, G-band absorption, luminosity, radius and spectroscopic
masses are given. The minimum and maximum mass of the secondary, mass ratio
and filling factor are also presented, adopting a circular orbit for all
the binaries.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablee1.dat 242 282 Stellar parameters for the primary star
tablee2.dat 186 282 Mass estimate, mass ratio, filling factor
--------------------------------------------------------------------------------
See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
Byte-by-byte Description of file: tablee1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaDR3 Star Name (Gaia DR3 source_id)
21- 40 F20.15 d Porb Orbital period
42- 47 F6.1 K Teff Effective temperature
49- 53 F5.1 K e_Teff Effective temperature uncertainty
55- 59 F5.3 [cm/s2] logg Stellar surface gravity in log scale
61- 65 F5.3 [cm/s2] e_logg Stellar surface gravity uncertainty
67- 87 F21.19 mag AG G-band absorption
89-109 F21.19 mag e_AG G-band absorption uncertainty
111-130 F20.15 Lsun L1 Stellar luminosity of the primary star
132-152 F21.16 Lsun e_L1 Stellar luminosity uncertainty
154-172 F19.15 Rsun R1 Stellar radius of the primary star
174-193 F20.17 Rsun e_R1 Stellar radius uncertainty
195-213 F19.17 Msun M1 Stellar mass of the primary
215-234 F20.18 Msun e_M1 Stellar mass uncertainty
236 I1 --- Source Source of the atmospheric parameters
238 A1 --- Flag [GRU] Flag for the quality of the light
curve (1)
240-242 A3 --- VType [ELL ROT] Variability type (G1)
--------------------------------------------------------------------------------
Note (1): Flag as follows:
G = Good
R = Regular
U = Uncertain
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablee2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaDR3 Star Name (Gaia DR3 source_id)
21- 39 F19.17 Msun M2min Minimum mass of the secondary
41- 60 F20.18 Msun e_M2min Minimum mass of the secondary uncertainty
62- 79 F18.16 Msun M2max ?=- Maximum mass of the secondary
81-100 F20.18 Msun e_M2max ?=- Maximum mass of the secondary uncertainty
102-120 F19.17 --- qmin Minimum mass ratio
122-141 F20.18 --- e_qmin Minimum mass ratio uncertainty
143-161 F19.17 --- Filfac Filling factor
163-182 F20.18 --- e_Filfac Filling factor uncertainty
184-186 A3 --- VType [ELL ROT] Variability type (G1)
--------------------------------------------------------------------------------
Global notes:
Note (G1): Variability type as follows:
ROT = Rotational
ELL = Ellipsoidal
--------------------------------------------------------------------------------
Acknowledgements:
Camila Navarrete, camila.navarrete(at)oca.eu
(End) Patricia Vannier [CDS] 17-Feb-2025