J/PASP/136/H4202 Wide Post-common Envelope Binaries from Gaia (Yamaguchi+, 2025)
Wide post-common envelope binaries from Gaia:
Orbit validation and formation Models.
Yamaguchi N., El-Badry K., Rees N.R., Shahaf S., Mazeh T., Andrae R.
<Publ. Astron. Soc. Pac. 136, 084202 (2025)>
=2025PASP..136h4202Y 2025PASP..136h4202Y (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Stars, white dwarf ;
Radial velocities ; Optical
Keywords: Binary stars - White dwarf stars - Asymptotic giant branch stars -
Astrometry
Abstract:
Astrometry from Gaia DR3 has enabled the discovery of a sample of
3000+ binaries containing white dwarfs (WD) and main-sequence (MS)
stars in relatively wide orbits, with orbital periods Porb=(100-1000)
days. This population was not predicted by binary population synthesis
models before Gaia and - if the Gaia orbits are robust - likely
requires very efficient envelope ejection during common envelope
evolution (CEE). To assess the reliability of the Gaia solutions, we
measured multi-epoch radial velocities (RVs) of 31 WD+MS binary
candidates with Porb=(40-300) days and AstroSpectroSB1 orbital
solutions. We jointly fit the RVs and astrometry, allowing us to
validate the Gaia solutions and tighten constraints on component
masses. We find a high success rate for the Gaia solutions, with only
2 out of the 31 systems showing significant discrepancies between
their Gaia orbital solutions and our RVs. Joint fitting of RVs and
astrometry allows us to directly constrain the secondary-to-primary
flux ratio , and we find S≲0.02 for most objects, confirming the
companions are indeed WDs. We tighten constraints on the binaries'
eccentricities, finding a median e∼0.1. These eccentricities are much
lower than those of normal MS+MS binaries at similar periods, but much
higher than predicted for binaries formed via stable mass transfer. We
present MESA single and binary evolution models to explore how the
binaries may have formed. The orbits of most binaries in the sample
can be produced through CEE that begins when the WD progenitor is an
AGB star, corresponding to initial separations of 2-5au. Roughly
50% of all post-common envelope binaries are predicted to have first
interacted on the AGB, ending up in wide orbits like these systems.
Description:
In this work, we presented follow-up spectroscopic observations of 31
MS+WD binaries with orbital periods ranging from ∼40 to 300 days and
AstroSpectroSB1solutions from Gaia DR3. These were selected from the
broader sample of candidates selected by Shahaf et al.
(2024MNRAS.529.3729S 2024MNRAS.529.3729S). By jointly fitting the RVs from our spectra and
astrometry, we validated the Gaia orbits and obtained tightened
constraints on their stellar and orbital parameters.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 82 31 Basic Information from Gaia DR3 of all Objects
Studied in this Work
table2.dat 66 135 All RVs Collected for the 31 Objects of this Work
--------------------------------------------------------------------------------
See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name Name (JHHMM+DDMM)
12- 30 I19 --- GaiaDR3 Gaia DR3 Source ID
32- 40 F9.5 deg RAdeg Right ascension (ICRS) at Ep=2016.0
42- 50 F9.5 deg DEdeg Declination (ICRS) at Ep=2016.0
52- 56 F5.2 mag Gmag Gaia G magnitude
58- 62 F5.2 --- GoF GoF is the Gaia goodnessoffit
64- 69 F6.2 d Porb Orbital period reported by Gaia
71- 75 F5.2 mas plx Gaia parallax
77- 80 F4.2 mas e_plx Gaia parallax error
82 I1 --- nRV Number of RVs we measured for each object
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name Name (JHHMM+DDMM)
12- 30 I19 --- GaiaDR3 Gaia DR3 Source ID
32- 44 F13.5 d JD Julian date of observation
46- 53 F8.3 km/s RV Radial velocity
55- 59 F5.3 km/s e_RV Radial velocity error
61- 66 A6 --- Inst Instrument/Catalog
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 11-Jun-2025