HD 131399

Short description: Star in the constellation Centaurus

HD 131399

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)

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]

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]

## Contents

* 1 Stellar system
* 2 Planetary system
* 2.1 Characteristics
* 3 References
* 4 Notes

## Stellar system

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]

## Planetary system

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]

### Characteristics

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]

## References

1. ↑ 1.0 1.1 van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. doi:10.1051/0004-6361:20078357. Bibcode: 2007A&A...474..653V. http://www.aanda.org/index.php?option=com_article&access=bibcode&Itemid=129&bibcode=2007A%26A...474..653VFUL.
2. ↑ Høg, E. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355: L27–L30. Bibcode: 2000A&A...355L..27H.
3. ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 Wagner, K.; Apai, D.; Kasper, M.; Kratter, K.; McClure, M.; Robberto, M.; Beuzit, J.-L. (2016). "Direct imaging discovery of a Jovian exoplanet within a triple-star system". Science 353 (6300): 673–8. doi:10.1126/science.aaf9671. PMID 27386921. Bibcode: 2016Sci...353..673W. (Retracted, see doi:10.1126/science.abq1709)
4. ↑ Kharchenko, N. V. (2007). "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ~55000 stars and mean radial velocities of 516 Galactic open clusters and associations". Astronomische Nachrichten 328 (9): 889. doi:10.1002/asna.200710776. Bibcode: 2007AN....328..889K.
5. ↑ 5.00 5.01 5.02 5.03 5.04 5.05 5.06 5.07 5.08 5.09 5.10 5.11 5.12 5.13 5.14 5.15 Nielsen, Eric L. (2017). "Evidence that the Directly-Imaged Planet HD 131399 Ab is a Background Star". The Astronomical Journal 154 (6): 218. doi:10.3847/1538-3881/aa8a69. Bibcode: 2017AJ....154..218N.
6. ↑ 6.0 6.1 6.2 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G. Gaia EDR3 record for this source at VizieR.
7. ↑ 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 Przybilla, N.; Aschenbrenner, P.; Buder, S. (2017). "Candidate exoplanet host HD 131399A: A nascent Am star". Astronomy & Astrophysics 604: L9. doi:10.1051/0004-6361/201731384. Bibcode: 2017A&A...604L...9P.
8. ↑ 8.0 8.1 8.2 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G. Gaia EDR3 record for this source at VizieR.
9. ↑ 9.0 9.1 Wagner, Kevin; Apai, Dániel; Kasper, Markus; Kratter, Kaitlin; McClure, Melissa; Robberto, Massimo; Beuzit, Jean-Luc (2022-04-15). "Retraction" (in en). Science 376 (6590): 255. doi:10.1126/science.abq1709. ISSN 0036-8075. PMID 35420970. Bibcode: 2022Sci...376..255W. https://www.science.org/doi/10.1126/science.abq1709.
10. ↑ 10.0 10.1 "HD 131399Ab: Astronomers Find Super-Jupiter in Triple-Star System | Astronomy | Sci-News.com" (in en-US). http://www.sci-news.com/astronomy/hd-131399ab-super-jupiter-triple-star-system-04008.html.
11. ↑ Lagrange, A.-M.; Keppler, M.; Beust, H.; Rodet, L.; Meunier, N.; Lillo-Box, J.; Bonnefoy, M.; Galland, F. (2017). "Discovery of a stellar companion to HD 131399A". Astronomy & Astrophysics 608: L9. doi:10.1051/0004-6361/201730978. Bibcode: 2017A&A...608L...9L.
12. ↑ 12.0 12.1 "This strange new planet has three suns". CBS News. 7 July 2016. https://www.cbsnews.com/news/planet-with-three-suns-triple-sunrises-sunsets/.
13. ↑ Veras, Dimitri; Mustill, Alexander J.; Gänsicke, Boris T. (2017). "The unstable fate of the planet orbiting the a star in the HD 131399 triple stellar system". Monthly Notices of the Royal Astronomical Society 465 (2): 1499. doi:10.1093/mnras/stw2821. Bibcode: 2017MNRAS.465.1499V.
14. ↑ "A Surprising Planet with Three Suns". ESO. https://www.eso.org/public/news/eso1624/.
15. ↑ Miller, Michael (12 April 2017). "UC mountaineer, galactic explorer". University of Cincinnati. http://magazine.uc.edu/editors_picks/recent_features/scorpion.html.
16. ↑ Oransky, Ivan (14 April 2022). "Triple sunrise, triple sunset: Science paper retracted when it turns out a planet is a star". https://retractionwatch.com/2022/04/14/triple-sunrise-triple-sunset-science-paper-retracted-when-it-turns-out-a-planet-is-a-star/#more-124683.
17. ↑ "16-million-year-old planet with three suns discovered". MSN. 8 July 2016. https://www.msn.com/en-gb/news/techandscience/16-million-year-old-planet-with-three-suns-discovered/ar-BBu52Bi?li=BBoPOOl.

## Notes

1. ↑ There are two solutions; the other one is 75 ± 10°.
2. ↑ There are two solutions; the other one is 310 ± 10°.

* v
* t
* e

Centaurus constellation

Stars (list)|

| Bayer|

* α (Rigil Kentaurus for A, Toliman for B, Proxima Centauri for C)
* β (Hadar)
* γ
* δ
* ε
* ζ
* η
* θ (Menkent)
* ι
* κ
* λ
* μ
* ν
* ξ1
* ξ2
* ο1
* ο2
* π
* ρ
* σ
* τ
* υ1
* υ2
* φ
* χ
* ψ

|

Flamsteed|

* 1 (i)
* 2 (g)
* 3 (k)
* 4 (h)

Variable|

* R
* T
* V
* Y
* RR
* SV
* SX
* BV
* DY
* V744
* V761 (a)
* V763 (C1)
* V766
* V803
* V810
* V816 (Przybylski's Star)
* V831
* V842
* V863
* V945 (H)
* V1032

HR|

* 4460 (A)
* 4466 (C2)
* 4476 (C3)
* 4499
* 4522
* 4523
* 4537 (j)
* 4546 (B)
* 4620 (E)
* 4652 (D)
* 4682 (F)
* 4712 (x1)
* 4721
* 4724 (x2)
* 4732 (G)
* 4748 (u)
* 4796
* 4817 (l)
* 4831 (w)
* 4874 (p)
* 4888 (e)
* 4889 (n)
* 4940 (f)
* 4979
* 4989
* 5006 (r)
* 5035 (J)
* 5041 (m)
* 5071 (K)
* 5089 (d)
* 5141 (Q)
* 5172 (M)
* 5174 (z)
* 5207 (N)
* 5222 (y)
* 5241
* 5297
* 5358 (v)
* 5371
* 5471 (b)
* 5485 (c1)
* 5489 (c2)

HD|

* 96660
* 97413
* 98176
* 101930
* 102117 (Uklun)
* 103197
* 107914
* 109749
* 113538
* 113766
* 114386
* 114729
* 117207
* 117618 (Dofida)
* 121228
* 121504
* 125072
* 125595
* 131399

Other|

* WASP-15 (Nyamien)
* 2M1207
* BPM 37093
* Centaurus X-3 (Krzeminski's Star)
* Nova Centauri 2013
* Proxima Centauri

Star clusters|

| Open|

* IC 2944
* NGC 3766
* NGC 4230
* NGC 5281
* NGC 5316
* NGC 5460
* NGC 5617
* NGC 5662
* Stock 16

|

Globular|

* NGC 5286
* Omega Centauri

Nebulae|

| H II|

* IC 2944

|

Planetary|

* Boomerang Nebula
* Fleming 1
* NGC 3918
* NGC 5307
* Southern Crab Nebula

SNR|

* G292.0+1.8
* SN 185 (RCW 86)

Galaxies|

| NGC|

* 3783
* 4444
* 4603
* 4622
* 4650A
* 4683
* 4696
* 4706
* 4709
* 4729
* 4730
* 4743
* 4744
* 4945
* 4976
* 5011
* 5011A
* 5026
* 5090
* 5091
* 5102
* 5114
* 5161
* 5253
* 5291
* 5398
* 5408

|

Other|

* ESO 325-G004
* ESO 444-46

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