J/MNRAS/509/3355 Binaries in the APOGEE-Gaia Binary Catalog (Lewis+, 2022)
Close substellar-mass companions in stellar wide binaries: discovery and
characterization with APOGEE and Gaia DR2.
Lewis H.M., Anguiano B., Majewski S.R., Nidever D.L., Badenes C.,
De Lee N., Hasselquist S., Mazzola Daher C., Stassun K.G., Bizyaev D.,
Godoy-Rivera D., Nitschelm C., Oravetz A., Pan K., Roman-Lopes A.
<Mon. Not. R. Astron. Soc. 509, 3355-3370>
=2022MNRAS.509.3355L 2022MNRAS.509.3355L (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, nearby ; Stars, double and multiple ;
Binaries, spectroscopic ; Stars, normal ; Stars, white dwarf ;
Photometry ; Optical ; Infrared ; Combined data ;
Radial velocities ; Positional data ; Effective temperatures ;
Abundances ; Stars, masses
Keywords: techniques: radial velocities - stars: abundances - binaries: close
Abstract:
We present a search for close, unresolved companions in a subset of
spatially resolved Gaia wide binaries containing main-sequence stars
within 200 pc of the Sun, utilizing the APOGEE-Gaia Wide Binary
Catalog. A catalogue of 37 wide binaries was created by selecting
pairs of stars with nearly identical Gaia positions, parallaxes, and
proper motions, and then confirming candidates to be gravitationally
bound pairs using APOGEE radial velocities. We identify close,
unresolved stellar and substellar candidate companions in these
multiple systems using (1) the Gaia binary main sequence and (2)
observed periodic radial velocity variations in APOGEE measurements
due to the influence of a close substellar-mass companion. The studied
wide binary pairs reveal a total of four stellar-mass close companions
in four different wide binaries, and four substellar-mass close
companion candidates in two wide binaries. The latter are therefore
quadruple systems, with one substellar-mass companion orbiting each
wide binary component in an S-type orbit. Taken at face value, these
candidate systems represent an enhancement of an order of magnitude
over the expected occurrence rate of ∼2 per cent of stars having
substellar companions > 2 MJup within ∼100-d orbits; we discuss
implications and possible explanations for this result. Finally, we
compare chemical differences between the components of the wide
binaries and the components of the candidate higher-order systems and
find that any chemical influence or correlation due to the presence of
close companions to wide binary stars is not discernible.
Description:
In the present work, we aim to identify triple- and higher-order
multiple candidates and to explore the possibility for the detection
of the chemical imprints of exoplanet formation, utilizing precise RV
measurements from the Sloan Digital Sky Survey (SDSS-IV; Blanton et
al. 2017AJ....154...28B 2017AJ....154...28B) APOGEE spectroscopic survey for 37 wide
binaries selected from the wide binary sample presented in El-Badry &
Rix (2018MNRAS.480.4884E 2018MNRAS.480.4884E, Cat. J/MNRAS/480/4884) containing more than
50000 wide binaries. We construct our APOGEE-Gaia Wide Binary Catalog
by searching Gaia DR2 (Gaia Collaboration 2018A&A...616A...1G 2018A&A...616A...1G, Cat. I/345)
for pairs of stars within 200 pc of the Sun, with positions, proper
motions, and parallaxes consistent with being gravitationally bound,
(i.e see the section Introduction).
The APOGEE survey (Majewski et al. 2017AJ....154...94M 2017AJ....154...94M, Cat. III/284)
is a high-resolution (R ∼ 22, 500), high signal-to-noise ratio (S/N >
100), infrared (1.51-1.69 µm), spectroscopic survey using twin
spectrographs (Wilson et al. 2019PASP..131e5001W 2019PASP..131e5001W) attached to the
2.5-m Sloan telescope at APO in the Northern hemisphere (Gunn et al.
2019PASP..131e5001W 2019PASP..131e5001W) and the du Pont telescope at Las Campanas
Observatory (LCO) in the Southern hemisphere. The latest APOGEE-2 data
release (SDSS DR16; Ahumada et al. 2020ApJS..249....3A 2020ApJS..249....3A, Cat. V/154;
Jonsson et al. 2020AJ....160..120J 2020AJ....160..120J, Cat. III/284) comprises spectra
for ∼437000 unique stars, along with stellar parameters and abundances
for over 20 individual chemical elements, derived from the APOGEE
Stellar Parameter and Chemical Abundance Pipeline. In addition to
elemental abundances, APOGEE provides multiepoch RV measurements,
which have an internal precision better than ∼0.1 km/s.
The two catalogues were cross-matched adopting a 1-arcsec positional
tolerance. The cross-match of the two catalogues contains only MS/MS
wide binary pairs. The catalogue used in the present work contains
only those wide binaries for which we have APOGEE spectra (including
stellar parameters and abundances from ASPCAP) for both components of
the binary, as well as high-quality astrometry and photometry from
Gaia, (i.e see the section 2 APOGEE-GAIA wide binary catalog).
As explained in the section 2.1 Selection of candidate wide binaries,
to be considered wide binaries we require candidate wide binaries to
pass some criteria selections such as APOGEE RVs consistent to within
5 km/s (i.e. |RVprimary - RVsecondary| =< 5 km/s, where
RVprimary and RVsecondary are the S/N-weighted average RVs for the
primary and secondary stars in the WB, respectively. Aftermath, the
resulting APOGEE-Gaia Wide Binary Catalog contains 37 genuine MS/MS
wide binaries with separations between 300 and 50000 A.U, all within
200 pc of the Sun. All of the stars in the catalogue have been
observed exclusively by the APOGEE-2N instrument at APO. This is by
and large due to the relatively few stars that had been observed by
the APOGEE-2S instrument at LCO at the time the DR16 data base was
assembled. Results such as Vscatter are compiled in the table5.dat.
In our work, we detail the two methods utilized for detecting
candidate close companions in the section 3 Close companion search
methodology and the section 4 gives detailed notes about individual
triple- and higher-order systems, as well as a brief discussion of the
abundance differences of all 37 wide binaries, versus just those wide
binaries found to host stellar- and substellar-mass companions.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 85 74 37 Binary systems in the APOGEE-Gaia Wide Binary
Catalog
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/MNRAS/480/4884 : Gaia wide binaries (El-Badry+, 2018)
III/284 : APOGEE-2 data from DR16 (Johnsson+, 2020)
V/154 : Sloan Digital Sky Surveys (SDSS), Release 16 DR16
(Ahumada+, 2020)
J/ApJ/646/523 : Exoplanet systems with stellar companions (Raghavan+, 2006)
Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- ID Catalogue identifier code (Catalogue_ID)
5- 21 A17 --- 2MASS 2MASS JHHMMSSss±DDMMSSs source
designation (2MASS_ID)
23- 28 F6.2 arcsec Sep ?=- Binary seperation angle (Sep)
30- 31 I2 --- Nvisits Number of visits per star (N_VISITS) (1)
33 A1 --- l_Vscatter Upper limit flag on Vscatter
35- 40 F6.4 km/s Vscatter ?=- Radial velocity scatter (V_SCATTER)
42- 45 I4 K Teff Effective temperature (TEFF)
47- 49 I3 K e_Teff Mean uncertainty of Teff (TEFF_E)
51- 55 F5.3 [cm/s2] logg Surface gravity (LOGG)
57- 61 F5.3 [cm/s2] e_logg Mean uncertainty of logg (LOGG_E)
63- 68 F6.3 [-] [M/H] Spectroscopic metallicity from APOGEE (M_H)
70- 74 F5.3 [-] e_[M/H] Mean uncertainty of [M/H] (MHE)
76- 79 F4.2 Msun M* Stellar mass (M_STAR)
81- 85 F5.3 Msun e_M* Mean uncertainty of M* (MSTARE)
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Note (1): APOGEE 'visit' is defined as the spectrum of a source from a single
fibre plugplate's observation on a night (∼1h of exposure).
The total survey number of APOGEE visits scheduled for a star depends
on its H-band brightness, with fainter targets requiring more visits
to obtain a survey-required minimum total S/N of 100, at the
completion of the survey, most stars are expected to have a minimum
of three visits to accomplish this goal.
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History:
From electronic version of the journal
(End) Luc Trabelsi [CDS] 24-Sep-2024