The right side shows an image taken by ESO's VLT HAWK-I in near-infrared. The white dwarf is marked with an arrow. The left side shows an image taken by the NASA/ESA HST WFC3 also in near-infrared wavelengths. The sub-brown dwarf appears as green pixels (2014) and purple pixels (2015) in an insert. | |
Observation data Epoch J2000 [1] Equinox J2000 [1] | |
---|---|
Constellation | Volans |
Right ascension | 08h 06m 53.75366s [2] |
Declination | −66° 18′ 16.7011″ [2] |
Characteristics | |
Spectral type | DQ4.2 [3] [4] + Y1 [5] |
Apparent magnitude (B) | 13.74 [6] / - |
Apparent magnitude (V) | 13.71 [6] / - |
Apparent magnitude (R) | 13.64 [6] / - |
Apparent magnitude (I) | 13.60 [6] / - |
Apparent magnitude (J) | 13.704 ± 0.023 [1] / ~25.42 [7] |
Apparent magnitude (H) | 13.739 ± 0.025 [1] / ~25.29 [7] |
Apparent magnitude (K) | 13.781 ± 0.043 [1] / - |
Astrometry | |
Proper motion (μ) |
RA: 335.519(16)
mas/
yr
[2] Dec.: −288.994(17) mas/ yr [2] |
Parallax (π) | 51.9970 ± 0.0141 mas [2] |
Distance | 62.73 ± 0.02
ly (19.232 ± 0.005 pc) |
Absolute magnitude (MV) | 12.30 [6] / - |
Details | |
Component A | |
Mass | 0.58 ± 0.03 [6] M☉ |
Surface gravity (log g) | 8.00 ± 0.05 [6] cgs |
Temperature | 10205 ± 390 [6] K |
Age | 1.5–2.7 [7] Gyr |
Component B | |
Mass | 7–9 [7] MJup |
Surface gravity (log g) | 4.2–4.3 [7] cgs |
Temperature | 325–350 [7] K |
Metallicity | <0 [7] |
Position (relative to A) | |
Component | B |
Angular distance | 130.2 ± 0.2 ″ [8] |
Position angle | 104.2 ± 0.2° [8] |
Projected separation | 2500 AU [8] |
Other designations | |
Database references | |
SIMBAD | data |
WD 0806−661 (L 97-3, GJ 3483), formally named Maru, [9] is a DQ white dwarf with an extremely cold Y-type substellar companion (designated "B"), located in the constellation Volans at 62.7 light-years (19.2 parsecs) from Earth. The companion was discovered in 2011, and is the only known Y-type companion to a star or stellar remnant. At the time of its discovery WD 0806-661 B had the largest actual (2500 AU) and apparent separation (more than 2 arcminutes) of any known planetary-mass object, as well as being the coldest directly imaged substellar object then known.
Component WD 0806-661 B was discovered in 2011 with the Spitzer Space Telescope. Its discovery paper is Luhman et al., 2011. The secondary has a mass between 7 and 9 MJ and a temperature between 325 and 350 kelvins (52 and 77 °C; 125 and 170 °F). [7] At the time of its discovery, WD 0806−661 B was the coldest " brown dwarf" that has ever been found. [8] The object is too faint to acquire a spectrum even with the Hubble Space Telescope, however the spectral type of this object was estimated to be Y1 based on its detection in Hubble images at near-infrared wavelengths. [5] The photometric colors of this object suggest that it is metal-poor. The metal-poor composition of the companion could explain the DQ spectral type of the primary white dwarf. [7] Hydrogen-deficient AGB stars might evolve into DB white dwarfs and then into DQ white dwarfs as they cool down. [10]
In August 2022, WD 0806-661 and its planetary-mass companion were included among 20 systems to be named by the third NameExoWorlds project. [11] The approved names, proposed by a team from South Korea, were announced in June 2023. WD 0806-661 is named Maru and its companion is named Ahra, after Korean words meaning "sky" and "ocean". [9]
The right side shows an image taken by ESO's VLT HAWK-I in near-infrared. The white dwarf is marked with an arrow. The left side shows an image taken by the NASA/ESA HST WFC3 also in near-infrared wavelengths. The sub-brown dwarf appears as green pixels (2014) and purple pixels (2015) in an insert. | |
Observation data Epoch J2000 [1] Equinox J2000 [1] | |
---|---|
Constellation | Volans |
Right ascension | 08h 06m 53.75366s [2] |
Declination | −66° 18′ 16.7011″ [2] |
Characteristics | |
Spectral type | DQ4.2 [3] [4] + Y1 [5] |
Apparent magnitude (B) | 13.74 [6] / - |
Apparent magnitude (V) | 13.71 [6] / - |
Apparent magnitude (R) | 13.64 [6] / - |
Apparent magnitude (I) | 13.60 [6] / - |
Apparent magnitude (J) | 13.704 ± 0.023 [1] / ~25.42 [7] |
Apparent magnitude (H) | 13.739 ± 0.025 [1] / ~25.29 [7] |
Apparent magnitude (K) | 13.781 ± 0.043 [1] / - |
Astrometry | |
Proper motion (μ) |
RA: 335.519(16)
mas/
yr
[2] Dec.: −288.994(17) mas/ yr [2] |
Parallax (π) | 51.9970 ± 0.0141 mas [2] |
Distance | 62.73 ± 0.02
ly (19.232 ± 0.005 pc) |
Absolute magnitude (MV) | 12.30 [6] / - |
Details | |
Component A | |
Mass | 0.58 ± 0.03 [6] M☉ |
Surface gravity (log g) | 8.00 ± 0.05 [6] cgs |
Temperature | 10205 ± 390 [6] K |
Age | 1.5–2.7 [7] Gyr |
Component B | |
Mass | 7–9 [7] MJup |
Surface gravity (log g) | 4.2–4.3 [7] cgs |
Temperature | 325–350 [7] K |
Metallicity | <0 [7] |
Position (relative to A) | |
Component | B |
Angular distance | 130.2 ± 0.2 ″ [8] |
Position angle | 104.2 ± 0.2° [8] |
Projected separation | 2500 AU [8] |
Other designations | |
Database references | |
SIMBAD | data |
WD 0806−661 (L 97-3, GJ 3483), formally named Maru, [9] is a DQ white dwarf with an extremely cold Y-type substellar companion (designated "B"), located in the constellation Volans at 62.7 light-years (19.2 parsecs) from Earth. The companion was discovered in 2011, and is the only known Y-type companion to a star or stellar remnant. At the time of its discovery WD 0806-661 B had the largest actual (2500 AU) and apparent separation (more than 2 arcminutes) of any known planetary-mass object, as well as being the coldest directly imaged substellar object then known.
Component WD 0806-661 B was discovered in 2011 with the Spitzer Space Telescope. Its discovery paper is Luhman et al., 2011. The secondary has a mass between 7 and 9 MJ and a temperature between 325 and 350 kelvins (52 and 77 °C; 125 and 170 °F). [7] At the time of its discovery, WD 0806−661 B was the coldest " brown dwarf" that has ever been found. [8] The object is too faint to acquire a spectrum even with the Hubble Space Telescope, however the spectral type of this object was estimated to be Y1 based on its detection in Hubble images at near-infrared wavelengths. [5] The photometric colors of this object suggest that it is metal-poor. The metal-poor composition of the companion could explain the DQ spectral type of the primary white dwarf. [7] Hydrogen-deficient AGB stars might evolve into DB white dwarfs and then into DQ white dwarfs as they cool down. [10]
In August 2022, WD 0806-661 and its planetary-mass companion were included among 20 systems to be named by the third NameExoWorlds project. [11] The approved names, proposed by a team from South Korea, were announced in June 2023. WD 0806-661 is named Maru and its companion is named Ahra, after Korean words meaning "sky" and "ocean". [9]