WD J1953−1019

Pan-STARRS color composite image of the WD J1953−1019 system, with the three components annotated. [a]
Observation data Epoch 2015.5       Equinox 2015.5
Constellation	Aquila
Right ascension	A: 19h 53m 33.11s B: 19h 53m 35.99s C: 19h 53m 36.02s
Declination	A: −10° 19′ 55.10″ B: −10° 19′ 31.76″ C: −10° 19′ 29.49″
Characteristics
Evolutionary stage	White dwarf
Spectral type	DA
Apparent magnitude (V)	17.27 (A) · 16.05 (B) · 16.29 (C)
Apparent magnitude (G)	17.28 (A) · 16.35 (B) · 16.44 (C)
Apparent magnitude (B)	17.27 (A) · 16.05 (B) · 16.29 (C)
Apparent magnitude (R)	17.30 (A) · 16.30 (B) · 16.44 (C)
Apparent magnitude (g)	17.18 (A) · 16.15 (B) · 16.24 (C)
Astrometry
A
Proper motion (μ)	RA: −10.81 ± 0.25  mas/ yr Dec.: −16.10 ± 0.15  mas/ yr
Distance	128.36 ± 2.40  pc
B
Proper motion (μ)	RA: −11.54 ± 0.18  mas/ yr Dec.: −16.33 ± 0.11  mas/ yr
Distance	130.37 ± 2.11  pc
C
Proper motion (μ)	RA: −10.94 ± 0.19  mas/ yr Dec.: −15.66 ± 0.12  mas/ yr
Distance	130.89 ± 2.01  pc
Details [1]
Mass	A: 0.63±0.03 B: 0.62±0.03 C: 0.60±0.03  M☉
Temperature	A: 13715±310 B: 22223±360 C: 22104±350  K
Other designations
A: Gaia DR2 4190500054845023488 B: Gaia DR2 4190499986125543168 C: Gaia DR2 4190499986125543296
Database references
A
SIMBAD	data
B
SIMBAD	data
C
SIMBAD	data

WD J1953−1019 is a hierarchical triple system of white dwarfs located at about 130 parsecs (about 420 light years) from the Earth. This is the first triple system of white dwarfs to be resolved. ^{[3] [1]} The three white dwarfs have an atmosphere of pure hydrogen and a mass of about 0.6 times that of the Sun.

The system consists of a central pair, WD J1953−1019 BC, and a distant companion, WD J1953−1019 A. WD J1953−1019 B and C correspond to the sources Gaia DR2 4190499986125543168 ^[4] and 4190499986125543296 ^[5] respectively. The white dwarfs of the central pair, WD J1953−1019 B and C, are separated 303.25±0.01  AU from each other while the distant companion, WD J1953−1019 A, orbits the barycenter, or center of mass, of the central binary at a distance of 6398.97±0.09 AU. ^[1]

The cooling age found by M. Perpinyà-Vallès and collaborators for the three white dwarfs is consistent, with an estimated value between 40 and 290 million years. ^[1] The three stars would each come from a star that had a mass between 1.6 and 2.6 times that of the Sun. A collision of the central pair due to Lidov-Kozai oscillations is unlikely as the system is dynamically stable. ^[1] However, if this collision occurred, it could produce a type Ia supernova below the Chandrasekhar mass. ^[1]

• SDSS J0106−1000 – a short-period binary white dwarf system, in the constellation Cetus
• WD J0651+2844 – another short-period binary white dwarf system, in the constellation Gemini