GJ 3470

GJ 3470 is a red dwarf star located in the constellation of Cancer, 96 light-years (29 parsecs) away from Earth. With a faint apparent magnitude of 12.3, it is not visible to the naked eye. It hosts one known exoplanet.[3][7]

GJ 3470 / Kaewkosin
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Cancer[1]
Right ascension 07h 59m 05.83953s[2]
Declination +15° 23′ 29.2361″[2]
Apparent magnitude (V) 12.330[3]
Characteristics
Evolutionary stage Main sequence red dwarf
Spectral type M2.0Ve[4]
Apparent magnitude (B) 13.5[4]
Apparent magnitude (V) 12.330[3]
Apparent magnitude (R) 11.934[4]
Apparent magnitude (J) 8.794[4]
Apparent magnitude (H) 8.206[4]
Apparent magnitude (K) 7.989[4]
B−V color index 1.17
V−R color index 0.396
J−H color index 0.588
J−K color index 0.217
Astrometry
Radial velocity (Rv)25.95±0.25[2] km/s
Proper motion (μ) RA: -185.706 mas/yr[2]
Dec.: -56.994 mas/yr[2]
Parallax (π)34.0172 ± 0.0255 mas[2]
Distance95.88 ± 0.07 ly
(29.40 ± 0.02 pc)
Details
Mass0.539+0.047
−0.043[5] M☉
Radius0.547±0.018[5] R☉
Luminosity (bolometric)0.029±0.002[6] L☉
Surface gravity (log g)4.695±0.046[5] cgs
Temperature3652±50[6] K
Metallicity [Fe/H]0.20±0.10[5] dex
Rotation21.54±0.49 d[6]
Age0.3-3[6] Gyr
Other designations
Kaewkosin, GJ 3470, LP 424-4, NLTT 18739, PM J07590+1523, TIC 19028197, 2MASS J07590587+1523294[4]
Database references
SIMBADdata
Exoplanet Archivedata

Nomenclature

The designation GJ 3470 comes from the Gliese Catalogue of Nearby Stars. This star was first included in the Third Catalogue of Nearby Stars, published in 1991 by Gliese and Jahreiß, hence the GJ prefix usually used for this star.[8]

In August 2022, GJ 3470 and its planet were included among 20 planetary systems to be named by the third NameExoWorlds project.[9] The approved names, proposed by a team from Thailand, were announced in June 2023. GJ 3470 is named Kaewkosin and its planet is named Phailinsiam, after names of precious stones in the Thai language.[10]

Properties

The star has a mass of 0.539 solar masses, a radius of 0.547 solar radii, and a temperature of about 3,652 K (3,379 °C; 6,114 °F).[3] It is about 0.3-3 billion years old, with a metallicity of 0.2 Fe/H and a rotation period of 21.54 days.[6] The star exhibits strong stellar activity, with three ultraviolet flares detected by 2021.[11]

Planetary system

At least one exoplanet has been discovered orbiting GJ 3470 at a distance of 0.035 astronomical units. The exoplanet, which is called GJ 3470 b, is a hot Neptune with an orbital period of 3.3 days. It was discovered in 2012 using radial velocity observations from HARPS, and transit observations from TRAPPIST.[12][13] The planet's atmosphere has been studied in detail, finding it to be composed mainly of hydrogen and helium, with Rayleigh scattering having been observed.[14] GJ 3470 b is losing mass to its star at a rate of about 1010 g/s.[15]

The GJ 3470 planetary system[5][6]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b / Phailinsiam 12.58+1.31
−1.28 M🜨		 0.0355±0.0019 3.33665240(14)[16] 0.114+0.052
−0.051		 89.13+0.26
−0.34°		 4.57±0.18 R🜨

Claims of additional planets

In July 2020, a group of amateur astronomers reported a new exoplanet candidate in an arXiv preprint, which they hypothesize to be the size of Saturn and inside the system's habitable zone, along with twelve tentative transits from not yet characterized exoplanets in the same star system.[17][18] If confirmed, GJ 3470 c would become the second exoplanet discovered by amateur astronomers, after KPS-1b, an exoplanet discovered by Ural State Technical University using amateur data.[19] The new GJ 3470 candidate was discovered with amateur data and through a project led by amateur astronomers.[17][20][21][22][23][24][25] However, it is important to note that the study in question has not been published in any scientific journal, nor has it been peer reviewed.

Similarly, on 21 April 2023, the same group of amateur astronomers reported two new exoplanet candidates co-orbiting, in a horseshoe exchange orbit, close to the star.[26] If confirmed, this would be the first ever discovery of co-orbiting exoplanets. However, again, the study in question is only in preprint form on arXiv, and it has not been peer reviewed and published in a respected scientific journal.[27][28]

As reported in a follow-up arXiv paper also by amateur astronomers, data from TESS rules out the existence of all three of these claimed planets. Thus, the "transits" observed by the amateur group were likely caused by visual artifacts. Radial velocity data can also rule out planets of the expected mass at the claimed periods, suggesting that if the claimed planets did exist, they would have very low densities.[29]

See also

References
  1. Staff (2 August 2008). "Finding the constellation which contains given sky coordinates". DJM.cc. Retrieved 16 July 2020.
  2. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  3. "GJ 3470". NASA Exoplanet Archive. Retrieved 16 July 2020.
  4. "GJ 3470". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 16 July 2020.
  5. Awiphan, S.; Kerins, E.; et al. (December 2016). "Transit timing variation and transmission spectroscopy analyses of the hot Neptune GJ3470b". Monthly Notices of the Royal Astronomical Society. 463 (3): 2574–2582. arXiv:1606.02962. Bibcode:2016MNRAS.463.2574A. doi:10.1093/mnras/stw2148.
  6. Kosiarek, Molly R.; Crossfield, Ian J. M.; et al. (March 2019). "Bright Opportunities for Atmospheric Characterization of Small Planets: Masses and Radii of K2-3 b, c, and d and GJ3470 b from Radial Velocity Measurements and Spitzer Transits". The Astronomical Journal. 157 (3): 97. arXiv:1812.08241. Bibcode:2019AJ....157...97K. doi:10.3847/1538-3881/aaf79c. S2CID 119440420.
  7. "GJ 3470". www.exoplanetkyoto.org. Retrieved 2020-07-16.
  8. "Dictionary of Nomenclature of Celestial Objects". Centre de données astronomiques de Strasbourg. Retrieved 4 May 2023.
  9. "List of ExoWorlds 2022". nameexoworlds.iau.org. IAU. 8 August 2022. Retrieved 27 August 2022.
  10. "2022 Approved Names". nameexoworlds.iau.org. IAU. Retrieved 7 June 2023.
  11. Bourrier, V.; Dos Santos, L. A.; Sanz-Forcada, J.; García Muñoz, A.; Henry, G. W.; Lavvas, P.; Lecavelier, A.; López-Morales, M.; Mikal-Evans, T.; Sing, D. K.; Wakeford, H. R.; Ehrenreich, D. (2021), "The Hubble PanCET program: Long-term chromospheric evolution and flaring activity of the M dwarf host GJ 3470", Astronomy & Astrophysics, 650: A73, arXiv:2103.09864, Bibcode:2021A&A...650A..73B, doi:10.1051/0004-6361/202140487, S2CID 232269667
  12. Bonfils, Xavier; et al. (28 September 2012). "A hot Uranus transiting the nearby M dwarf GJ3470. Detected with HARPS velocimetry. Captured in transit with TRAPPIST photometry". Astronomy & Astrophysics. 546: 8. arXiv:1206.5307. Bibcode:2012A&A...546A..27B. doi:10.1051/0004-6361/201219623. S2CID 12963626.
  13. "The Extrasolar Planet Encyclopaedia — GJ 3470 b". exoplanet.eu. Retrieved 2020-07-16.
  14. Benneke, Björn; Knutson, Heather A.; Lothringer, Joshua; Crossfield, Ian J.M.; Moses, Julianne I.; Morley, Caroline; Kreidberg, Laura; Fulton, Benjamin J.; Dragomir, Diana; Howard, Andrew W.; Wong, Ian; Désert, Jean-Michel; McCullough, Peter R.; Kempton, Eliza M.-R.; Fortney, Jonathan; Gilliland, Ronald; Deming, Drake; Kammer, Joshua (2019). "A sub-Neptune exoplanet with a low-metallicity methane-depleted atmosphere and Mie-scattering clouds". Nature Astronomy. 3 (9): 813–821. arXiv:1907.00449. Bibcode:2019NatAs...3..813B. doi:10.1038/s41550-019-0800-5. S2CID 256707037.
  15. Bourrier, V.; Lecavelier Des Etangs, A.; Ehrenreich, D.; Sanz-Forcada, J.; Allart, R.; Ballester, G. E.; Buchhave, L. A.; Cohen, O.; Deming, D.; Evans, T. M.; García Muñoz, A.; Henry, G. W.; Kataria, T.; Lavvas, P.; Lewis, N.; López-Morales, M.; Marley, M.; Sing, D. K.; Wakeford, H. R. (2018). "Hubble PanCET: An extended upper atmosphere of neutral hydrogen around the warm Neptune GJ 3470b". Astronomy & Astrophysics. 620: A147. arXiv:1812.05119. Bibcode:2018A&A...620A.147B. doi:10.1051/0004-6361/201833675. S2CID 239583863.
  16. Kokori, A.; et al. (14 February 2023). "ExoClock Project. III. 450 New Exoplanet Ephemerides from Ground and Space Observations". The Astrophysical Journal Supplement Series. 265 (1) 4. arXiv:2209.09673. Bibcode:2023ApJS..265....4K. doi:10.3847/1538-4365/ac9da4. Vizier catalog entry
  17. Scott, Phillip; Walter, Bradley; Ye, Quanzhi; Mitchell, David; Heiland, Leo; Gao, Xing; Palado, Alejandro; Otabek, Burkhonov; Casal, Jesus Delgado; Hill, Colin; Garcia, Alberto (2020-07-14). "GJ 3470 c: A Saturn-like Exoplanet Candidate in the Habitable Zone of GJ 3470". arXiv:2007.07373 [astro-ph.EP].
  18. "The Extrasolar Planet Encyclopaedia — GJ 3470 c". exoplanet.eu. Retrieved 2020-07-16.
  19. Burdanov, Artem; et al. (July 2018). "KPS-1b: The First Transiting Exoplanet Discovered Using an Amateur Astronomer's Wide-field CCD Data". Publications of the Astronomical Society of the Pacific. 130 (989): 074401. arXiv:1804.05551. Bibcode:2018PASP..130g4401B. doi:10.1088/1538-3873/aabde2. S2CID 55382183.
  20. Carter, Jamie. "Inside The 24/7 Search For Another Habitable Planet Within 100 Light Years Of Earth". Forbes. Retrieved 2020-07-19.
  21. Maloney, Dan (2020-07-19). "Hackaday Links: July 19, 2020". Hackaday. Retrieved 2020-07-20.
  22. "Saturn-Like Exoplanet Found in Habitable Zone of Gliese 3470 | Astronomy | Sci-News.com". Breaking Science News | Sci-News.com. Retrieved 2020-07-21.
  23. Beaty, James. "Local astronomer says he's detected new planet". McAlester News-Capital. Retrieved 2020-07-22.
  24. "Amateur-team spoort (mogelijke) nieuwe exoplaneet op - Astronomie.nl". www.astronomie.nl. Archived from the original on 2020-07-24. Retrieved 2020-07-24.
  25. Andy Tomaswick (2020-07-28). "Saturn-sized Planet Found in the Habitable Zone of Another Star. The First Planet Completely Discovered by Amateur Astronomers". Universe Today. Retrieved 2020-07-29.
  26. Scott, Phillip; Taylor, Jaxon; Beatty, Larry; Edlin, Jim; Keubler, Phil; Dennis, Mike; Higgins, David; Caballero, Albero; Garcia, Alberto (2023-04-23). "GJ3470-d and GJ3470-e: Discovery of Co-Orbiting Exoplanets in a Horseshoe Exchange Orbit". arXiv:2304.11769 [astro-ph.EP].
  27. "The Extrasolar Planet Encyclopaedia — GJ 3470 d". exoplanet.eu. Retrieved 2023-04-28.
  28. "The Extrasolar Planet Encyclopaedia — GJ 3470 e". exoplanet.eu. Retrieved 2023-04-28.
  29. Tarrants, Thomas; Li, Andrew (May 2023). "No Evidence for Additional Planets at GJ 3470 from TESS and Archival Radial Velocities". arXiv:2305.02551 [astro-ph.EP].
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