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SPECULOOS-3

SPECULOOS-3

SPECULOOS-3 (circled) as seen by 2MASS.
Observation data
Epoch J2000      Equinox J2000
Constellation Cygnus[1]
Right ascension 20h 49m 27.44052s[2]
Declination +33° 36′ 50.9686″[2]
Apparent magnitude (V) 17.8 (estimate)[3]
Characteristics
Evolutionary stage Red dwarf
Spectral type M6.5±0.5[4]
Apparent magnitude (B) 19[5]
Apparent magnitude (R) 16.4[5]
Apparent magnitude (G) 15.379[2]
Apparent magnitude (J) 11.5[6]
Apparent magnitude (H) 10.867±0.021[5]
Apparent magnitude (K) 10.54[6]
Astrometry
Proper motion (μ) RA: –207.809 mas/yr[2]
Dec.: –412.215 mas/yr[2]
Parallax (π)59.7005 ± 0.0434 mas[2]
Distance54.63 ± 0.04 ly
(16.75 ± 0.01 pc)[2]
Details[4]
Mass0.1009±0.0024 M☉
Radius0.123±0.0022 R☉
Luminosity0.000835±0.000019 L☉
Surface gravity (log g)5.265±0.014 cgs
Temperature2800±29 K
Metallicity [Fe/H]0.07±0.1 dex
Rotation1.34±0.14 d
Rotational velocity (v sin i)4.8±0.5 km/s
Age6.6+1.8
−2.4 Gyr
Other designations
Gaia DR2 1869054868256849920, Gaia DR3 1869054868256849920, LSPM J2049+3336, TIC 230741378, 2MASS J20492745+3336512, WISE J204927.26+333646.6
Database references
SIMBADdata

SPECULOOS-3, also known as LSPM J2049+3336, is a red dwarf star (spectral type M6.5) located 54.6 light-years from Earth[4] in the constellation Cygnus. It is one of the smallest known stars, and is much cooler, dimmer and smaller than the Sun, having 0.1 times the mass, 0.08% the Sun's luminosity, and an effective temperature of 2,800 K (2,530 °C), which is less than half of the Sun's temperature (5,772 K).[4] It is orbited by one known exoplanet, and is the second ultra-cool dwarf discovered to have a planetary system, after TRAPPIST-1.[7][8]

Stellar properties

The age of SPECULOOS-3 is constrained at 6.6 billion years, 44% older than the Solar System, with significant margins of error. A bayesian analysis of the star derived a mass of 0.101 M☉, an effective temperature of 2,800 K (2,530 °C; 4,580 °F) and a luminosity of 8.35×10−6 L☉. These characteristics classify SPECULOOS-3 as an ultracool dwarf, which are stars at the end of the main sequence, with low temperatures, low luminosites and sizes similar to Jupiter. It is spinning at a rotational velocity of 4.8 km/s and has a projected rotational period of 1.34 days.[4]

The stellar radius, computed using the Stefan–Boltzmann law, is 0.134 R☉ (93,000 kilometres).[4] This makes SPECULOOS-3 the second-smallest star known to host a transiting planet, just marginally larger than TRAPPIST-1,[4] and its size is similar to that of Jupiter.[9] Its apparent magnitude is estimated at 17.8,[3] which is too faint to be seen by the naked eye.

It was first discovered in 2005 as part of the LSPM-North catalog, whose objective was to map stars in the northern celestial hemisphere with proper motions larger than 0.15" per year and apparent magnitudes smaller than 21m.[3] Its trignometric parallax was first measured in 2014 at 67.5±1.7 mas, translating into a distance of 14.8 parsecs (48.27 ly).[6] Gaia Data Release 3 (2023) published a parallax of 59.7 milliarcseconds, translating into a distance of 16.75 parsecs (54.6 ly).[2] This make this star relatively close to Earth.[10]

Red dwarf stars such as SPECULOOS-3 are the most numerous type of stars, making up 70% of all stars in the Milky Way galaxy. They are expected to live 10 times more than the Sun, with lifespans longer than 100 billion years.[10]

Planetary system

See also: SPECULOOS-3 b

In 2024, an exoplanet was found around the star using the transit method.[11] Named SPECULOOS-3 b, it is an Earth-sized exoplanet that has a radius similar to that of Earth, equivalent to 0.98 Earth radii.[4] It takes only about 17 hours to complete an orbit around SPECULOOS-3, and, because of that proximity, it receives very high levels of radiation and is likely tidally locked, meaning that one side of the planet always faces its host star.[9] Its discovery was made using the SPECULOOS project, and was announced on 15 May 2024 in the academic journal Nature Astronomy.[12]

The mass of SPECULOOS-3 b has been not measured,[4] but it has been estimated by NASA's Eyes on Exoplanets at 0.894 ME.[13] Its equilibrium temperature is about 553 K (280 °C; 536 °F), meaning that its dayside is likely formed by solid rock.[4] The planet is an optimal target for characterization with the James Webb Space Telescope, giving more information about the planet's mineralogy[12] and the possibility of hosting an atmosphere.[14]

The SPECULOOS-3 planetary system[4]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b — 0.007330(55) 0.71912603(57) — 89.44±0.39° 0.977±0.022 R🜨

References

  1. ^ "Finding the constellation which contains given sky coordinates". djm.cc. 2 August 2008.
  2. ^ a b c d e f g 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. ^ a b c Lépine, Sébastien; Shara, Michael M. (2005-03-01). "A Catalog of Northern Stars with Annual Proper Motions Larger than 0.15" (LSPM-NORTH Catalog)". The Astronomical Journal. 129 (3): 1483–1522. arXiv:astro-ph/0412070. Bibcode:2005AJ....129.1483L. doi:10.1086/427854. ISSN 0004-6256. SPECULOOS-3's database entry at VizieR.
  4. ^ a b c d e f g h i j k Gillon, Michaël; Pedersen, Peter P.; Rackham, Benjamin V.; Dransfield, Georgina; Ducrot, Elsa; Barkaoui, Khalid; Burdanov, Artem Y.; Schroffenegger, Urs; Gómez Maqueo Chew, Yilen; Lederer, Susan M.; Alonso, Roi; Burgasser, Adam J.; Howell, Steve B.; Narita, Norio; de Wit, Julien (2024-05-15). "Detection of an Earth-sized exoplanet orbiting the nearby ultracool dwarf star SPECULOOS-3". Nature Astronomy. 8 (7): 865–878. arXiv:2406.00794. Bibcode:2024NatAs...8..865G. doi:10.1038/s41550-024-02271-2. ISSN 2397-3366.
  5. ^ a b c "LSPM J2049+3336". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved May 26, 2024.
  6. ^ a b c Dittmann, Jason A.; Irwin, Jonathan M.; Charbonneau, David; Berta-Thompson, Zachory K. (2014-04-01). "Trigonometric Parallaxes for 1507 Nearby Mid-to-late M Dwarfs". The Astrophysical Journal. 784 (2): 156. arXiv:1312.3241. Bibcode:2014ApJ...784..156D. doi:10.1088/0004-637X/784/2/156. ISSN 0004-637X. SPECULOOS-3's database entry at VizieR.
  7. ^ Anderson, Natali (2024-05-15). "Earth-Sized Exoplanet Found Orbiting Nearby Ultracool Red Dwarf". Sci.News. Retrieved 2024-05-28.
  8. ^ "Detection of an Earth-sized exoplanet orbiting the ultracool dwarf star SPECULOOS-3". ScienceDaily. Retrieved 2024-05-28.
  9. ^ a b Hill, Samantha (2024-05-16). "Found: An Earth-sized exoplanet named SPECULOOS-3 b". Astronomy Magazine. Retrieved 2024-05-26.
  10. ^ a b "Discovery Alert: An Earth-sized World and Its Ultra-cool Star - NASA Science". science.nasa.gov. Retrieved 2024-05-26.
  11. ^ "The Extrasolar Planet Encyclopaedia — SPECULOOS-3 b". Extrasolar Planets Encyclopaedia. Paris Observatory. Retrieved May 26, 2024.
  12. ^ a b "Astronomers discover new Earth-sized world orbiting an ultra-cool star". phys.org. May 15, 2024. Retrieved 2024-05-26.
  13. ^ "SPECULOOS-3 b - NASA Science". science.nasa.gov. Retrieved 2024-05-26.
  14. ^ Lea, Robert (2024-05-15). "Earth-size planet discovered around cool red dwarf star shares its name with a biscuit". Space.com. Retrieved 2024-05-29.
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