File:SPHERE observations of the planet HD 131399Ab.tif SPHERE image of HD 131399 A (top left), B and C (bottom right), and the background object (center) Credit: ESO/K. Wagner et al. | |
Observation data Equinox J2000.0]] (ICRS) | |
---|---|
Constellation | Centaurus |
Right ascension | 14h 54m 25.30919s[1] |
Declination | −34° 08′ 34.0412″[1] |
Apparent magnitude (V) | 7.07[2] |
Characteristics | |
Spectral type | A1V + G + K[3] |
Astrometry | |
Radial velocity (Rv) | 0.30 ± 1.3[4] km/s |
Distance | 351+15 −12 ly (107.9+4.5 −3.7[5] pc) |
A | |
Proper motion (μ) | RA: −30.702[6] mas/yr Dec.: −30.774[6] mas/yr |
Parallax (π) | 9.7480 ± 0.0357[6] mas |
Distance | 335 ± 1 ly (102.6 ± 0.4 pc) |
Absolute magnitude (MV) | 1.89[7] |
BC | |
Proper motion (μ) | RA: −31.523[8] mas/yr Dec.: −31.047[8] mas/yr |
Parallax (π) | 9.3021 ± 0.0633[8] mas |
Distance | 351 ± 2 ly (107.5 ± 0.7 pc) |
Orbit[3] | |
Primary | A |
Companion | BC |
Period (P) | 3556 ± 36 yr |
Semi-major axis (a) | 3.56 ± 0.03″ (349 ± 28 au) |
Eccentricity (e) | 0.13 ± 0.05 |
Inclination (i) | 45 to 65° |
Longitude of the node (Ω) | 265 ± 20[note 1]° |
Periastron epoch (T) | B 502 ± 33 |
Argument of periastron (ω) (secondary) | 145.3 ± 15[note 2]° |
Details | |
Age | 21.9+4.1 −3.8[5] Myr |
HD 131399 A | |
Mass | 1.95+0.08 −0.06[7] M☉ |
Radius | 1.51+0.13 −0.10[7] R☉ |
Luminosity | 14.8+2.6 −2.2[7] L☉ |
Surface gravity (log g) | 4.37±0.10[7] cgs |
Temperature | 9,200±100[7] K |
Rotational velocity (v sin i) | 26±2[7] km/s |
HD 131399 B | |
Mass | 0.95±0.04[5] M☉ |
Surface gravity (log g) | 4.40±0.03[5] cgs |
Temperature | 4,890+190 −170[5] K |
HD 131399 C | |
Mass | 0.35±0.04[5] M☉ |
Surface gravity (log g) | 4.45±0.05[5] cgs |
Temperature | 3,460±60[5] K |
Other designations | |
Database references | |
SIMBAD | data |
HD 131399 is a star system in the constellation of Centaurus. Based on the system's electromagnetic spectrum, it is located around 350 light-years (107.9 parsecs) away.[5] The total apparent magnitude is 7.07,[5] but because of interstellar dust between it and the Earth, it appears 0.22 ± 0.09 magnitudes dimmer than it should be.[5]
The brightest star, is a young A-type main-sequence star, and further out are two lower-mass stars.[3] A Jupiter-mass planet or a low-mass brown dwarf was once thought to be orbiting the central star, but this has been ruled out.[5][9]
The brightest star in the HD 131399 system is designated HD 131399 A. Its spectral type is A1V,[3] and it is 2.08 times as massive as the Sun.[5] The two lower-mass stars are designated HD 131399 B and C, respectively. B is a G-type main-sequence star, while HD 131399 C is a K-type main-sequence star.[3] Both stars are less massive than the Sun.[5]
HD 131399 B and C are located very close to each other, and the two orbit each other at about 10 AU.[10] In turn, the B-C pair orbits the central star A at a distance of 349 astronomical units (au). This orbit takes about 3,600 years to complete, and it has an eccentricity of about 0.13[3] The entire system is about 21.9 million years old.[5]
One paper has reported that HD 131399 A has a companion in an inclined 10-day orbit with a semi-major axis of 0.1 astronomical unit|AU.[11] HD 131399 A has been described as a "nascent Am star"; although it has a very slow projected rotation rate and would be expected to show chemical peculiarities, its spectrum is relatively normal, possibly due to its young age.[7]
File:An artist’s impression of planet in the HD 131399 system.tif The claimed discovery of a massive planet, named HD 131399 Ab, was announced in a paper published in the journal Science.[3] The object was imaged using the SPHERE imager of the Very Large Telescope at the European Southern Observatory, located in the Atacama Desert of Chile , and announced in a July 2016 paper in the journal Science.[3][12] It was thought to be a T-type object with a mass of 4 ± 1 MJ,[3] but its orbit would have been unstable, causing it to be ejected between the primary's red giant phase and white dwarf phase.[13] This was the first exoplanet candidate to be discovered by SPHERE. The image was created from two separate SPHERE observations: one to image the three stars and one to detect the faint planet.[14] After its discovery, the team unofficially named the system "Scorpion-1" and the planet "Scorpion-1b", after the survey that prompted its discovery, the Scorpion Planet Survey (principal investigator: Daniel Apai).[15]
In May 2017, observations made by the Gemini Planet Imager and including a reanalysis of the SPHERE data suggest that this target is, in fact, a background star. This object's spectrum seems to be like that of a K-type or M-type dwarf, not a T-type object as first thought. It also initially appeared to be associated with HD 131399, but this was because of its unusually high proper motion (in the top 4% fastest-moving stars).[5] After subsequent data published in 2022 confirmed that the object is a background star, the paper announcing the putative discovery was retracted.[9][16]
The planet was thought to be about 16 million years old, with a mass of 4 (± 1) MJ (Jupiter masses), and a temperature of 850 K (577 °C; 1,070 °F) (± 50 K), which would make it one of the coldest and least massive directly imaged exoplanets.[10] Its atmosphere was shown to contain both water and methane through the use of near-infrared spectroscopy (1.4-1.6 μm).[3] Scientists believed it was unlikely that the planet harbored life due to it being gaseous. The planet was said to have "no liquid water, extremely powerful winds, and no surface; just below the uppermost layer of the atmosphere it rains liquid iron droplets."[17] One orbit of HD 131399 Ab was thought to take 550 years.[3][12]
Original source: https://en.wikipedia.org/wiki/HD 131399.
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