J/ApJ/894/53 ELM Survey South. I. RVs for 6 new ELM WDs (Kosakowski+, 2020)
The ELM Survey South.
I. An effective search for extremely low mass white dwarfs.
Kosakowski A., Kilic M., Brown W.R., Gianninas A.
<Astrophys. J., 894, 53 (2020)>
=2020ApJ...894...53K 2020ApJ...894...53K
ADC_Keywords: Stars, white dwarf; Stars, metal-deficient; Spectra, optical;
Radial velocities; Surveys; Stars, masses
Keywords: White dwarf stars ; Spectroscopy ; Radial velocity ; Compact objects
Abstract:
We begin the search for extremely low mass (M≤0.3M☉, ELM) white
dwarfs (WDs) in the southern sky based on photometry from the VST
ATLAS and SkyMapper surveys. We use a similar color selection method
as the Hypervelocity star survey. We switched to an astrometric
selection once Gaia Data Release 2 became available. We use the
previously known sample of ELM white dwarfs to demonstrate that these
objects occupy a unique parameter space in parallax and magnitude. We
use the SOAR 4.1m telescope to test the Gaia-based selection, and
identify more than two dozen low mass white dwarfs, including six new
ELM white dwarf binaries with periods as short as 2h. The better
efficiency of the Gaia-based selection enables us to extend the ELM
Survey footprint to the southern sky. We confirm one of our
candidates, J0500-0930, to be the brightest (G=12.6mag) and closest
(d=72pc) ELM white dwarf binary currently known. Remarkably, the
Transiting Exoplanet Survey Satellite (TESS) full-frame imaging data
on this system reveals low-level (<0.1%) but significant variability
at the orbital period of this system (P=9.5hr), likely from the
relativistic beaming effect. TESS data on another system, J0642-5605,
reveals ellipsoidal variations due to a tidally distorted ELM WD.
These demonstrate the power of TESS full-frame images in confirming
the orbital periods of relatively bright compact object binaries.
Description:
We relied on photometry from the VST ATLAS DR2+DR3 (see II/350) and
SkyMapper DR1 (see II/358) surveys to select blue stars with
low-surface gravity. See Sections 2.1 and 2.2.
We also use Gaia DR2 (see I/345) photometry and parallax measurements
to select white dwarf candidates. See Section 3.
We observed 532 unique systems over 14 nights across three observing
campaigns on 2017 March (NOAO Program ID: 2017A-0076), 2017 August
(NOAO Program ID: 2017B-0173), and 2018 March (NOAO Program ID:
2018A-0233) using the SOAR 4.1m telescope the Goodman high throughput
spectrograph, located on Cerro Pachon, Chile.
We observed 134 additional systems using the Walter Baade 6.5m
telescope with the MagE spectrograph, located at the Las Campanas
Observatory on Cerro Manqui, Chile.
We observed 12 additional systems using the Fred Lawrence Whipple
Observatory (FLWO) 1.5m Tillinghast telescope with the FAST
spectrograph, located on Mt. Hopkins, Arizona.
Finally, We observed 31 additional systems using the MMT 6.5m
telescope with the Blue Channel Spectrograph, located on Mt. Hopkins,
Arizona.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 108 8 The physical parameters of the eight new ELM WDs
identified in this work
table3.dat 55 6 Orbital parameters for the six new binaries
identified in this work
tableb1.dat 108 123 Table of 123 white dwarfs observed as a part of
our ATLAS+SkyMapper target selection
tableb2.dat 97 29 Table of 29 sdA+ELM candidates observed as a part
of our ATLAS+SkyMapper target selection;
see Section 2.7.
tableb3.dat 108 49 Table of 49 White Dwarfs identified through our
Gaia parallax target selection
tableb4.dat 97 7 Table of 7 sdB stars observed as a part of our
Gaia parallax target selection
tableb5.dat 36 157 Radial velocity data for the 6 new ELM WDs with
well-constrained orbital periods, as well as
for sdA J1425-0508
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See also:
II/350 : VLT Survey Telescope ATLAS (Shanks+, 2015)
II/358 : SkyMapper Southern Sky Survey. DR1.1 (Wolf+, 2018)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/ApJ/723/1072 : The ELM survey. I. Low-mass white dwarfs (Brown+, 2010)
J/ApJ/743/138 : Spectroscopic survey of bright WDs (Gianninas+, 2011)
J/ApJ/794/35 : Binary white dwarfs atmospheric param. (Gianninas+, 2014)
J/ApJ/818/155 : The ELM survey. VII. 15 new ELM WD cand. (Brown+, 2016)
J/A+A/595/A35 : Low-mass helium WDs evolutionary models (Istrate+, 2016)
J/MNRAS/455/3413 : New white dwarf & subdwarfs in SDSS DR12 (Kepler+, 2016)
J/ApJ/839/23 : Subdwarf A stars vs ELM WDs radial velocities (Brown+, 2017)
J/MNRAS/469/3688 : CSS Periodic Variable Star Catalogue (Drake+, 2017)
J/MNRAS/480/1547 : Full Evolutionary Sequences of Massive WDs (Lauffer+, 2018)
J/MNRAS/475/2480 : Extremely-low mass white dwarf star (Pelisoli+, 2018)
J/A+A/621/A38 : Gaia catalogue of hot subluminous stars (Geier+, 2019)
J/MNRAS/482/4570 : Gaia DR2 white dwarf candidates (Gentile Fusillo+, 2019)
Byte-by-byte Description of file: table2.dat tableb[1-4].dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- Gaia Gaia DR2 source identifier
21- 30 A10 --- AName Shortened position based name
used in this work
32- 34 A3 --- f_Gaia Object flag(s) (G1)
36- 37 I2 h RAh Hour of Right Ascension (J2000)
39- 40 I2 min RAm Minute of Right Ascension (J2000)
42- 46 F5.2 s RAs Second of Right Ascension (J2000)
48- 48 A1 --- DE- Sign of the Declination (J2000)
49- 50 I2 deg DEd Degree of Declination (J2000)
52- 53 I2 arcmin DEm Arcminute of Declination (J2000)
55- 59 F5.2 arcsec DEs Arcsecond of Declination (J2000)
61- 65 F5.2 mag Gmag [12.6/20.5] Gaia G band magnitude
67- 71 F5.2 mas Plx [-3.3/15.7]? Gaia DR2 Parallax
73- 76 F4.2 mas e_Plx [0.03/2.1]? Uncertainty in Plx
78- 82 I5 K Teff [7520/45580] Surface effective temperature
84- 87 I4 K e_Teff [5/8080] Uncertainty in Teff
89- 92 F4.2 [cm/s2] logg [5/9.2] Surface gravity, log (1)
94- 97 F4.2 [cm/s2] e_logg [0/1.4] Uncertainty in logg
99-103 F5.3 Msun Mass [0.15/1.3]? White dwarf mass
(not for Tables B2 and B4)
105-108 F4.2 Msun e_Mass [0.01/0.2]? Uncertainty in Mass
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Note (1): For Table B4, atmosphere parameters are based on pure-Hydrogen
atmosphere model fits, and should be used with caution.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- AName Shortened position based name used in this work
12- 14 A3 --- f_Gaia Object flag (G1)
16- 22 F7.5 d Per [0.088/0.7] Orbital period
24- 30 F7.5 d e_Per [1e-05/0.004] Uncertainty in Per
32- 36 F5.1 km/s K [138/368] Velocity semi-amplitude
38- 41 F4.1 km/s e_K [6.6/39.4] Uncertainty in K
43- 46 F4.2 Msun M2 [0.29/1] Binary component, minimum mass
48- 51 F4.2 Msun e_M2 [0.03/0.21] Uncertainty in M2
53- 55 F3.1 Gyr tmax [0.9/3.6]? Maximum gravitational wave merger time
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Byte-by-byte Description of file: tableb5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- AName Shortened position based name used in this work
12- 22 F11.6 d HJD [7835.65/8546.81] Heliocentric Julian date,
HJD-2450000
24- 30 F7.2 km/s HRV [-191.17/602.87] Heliocentric radial velocity
32- 36 F5.2 km/s e_HRV [5.14/31.33] Uncertainty in HRV
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Global notes:
Note (G1): Object flags as follows:
* = Targets also included in Pelisoli & Vos (2019MNRAS.488.2892P 2019MNRAS.488.2892P)
as ELM WD candidates based on Gaia colors
d = Targets are present in Geier et al. (2019A&A...621A..38G 2019A&A...621A..38G) Gaia hot
subluminous star catalogue.
g = Targets also present in the Gaia DR2 white dwarf catalogue of
Gentile Fusillo et al. (2019MNRAS.482.4570G 2019MNRAS.482.4570G)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 20-Sep-2021