SPECULOOS-3 b
| File:Artist's impression of SPECULOOS-3 b and its host star.jpg Artist's impression of SPECULOOS-3 b and its host star, a red dwarf much cooler, dimmer than the Sun. | |
| Discovery[2] | |
|---|---|
| Discovered by | Michael Gillon et al. |
| Discovery site | SPECULOOS |
| Discovery date | May 15, 2024 |
| Transit method[1] | |
| Designations | |
Named after | SPECULOOS |
| Orbital characteristics[2] | |
| 0.00733 AU | |
| 0.719 days (17 hours and 15 min.) | |
| Inclination | 89.44°±0.39° |
| Star | LSPM J2049+3336 (SPECULOOS-3) |
| Physical characteristics[2] | |
Mean radius | 0.977±0.02 R⊕ 0.07273 RJ |
| Mass | 0.894 M⊕ (estimate) |
| Temperature | 553±8 K (280±8 °C) |
SPECULOOS-3b is an Earth-sized exoplanet, orbiting the ultracool red dwarf star SPECULOOS-3. It is located relatively close to Earth, at a distance of 55 light-years.[3] SPECULOOS-3b 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.[4] Its discovery was made using the SPECULOOS project, and announced in May 2024 in the academic journal Nature Astronomy.[5]
The host star of SPECULOOS-3b is SPECULOOS-3 (LSPM J2049+3336, TIC 230741378), an ultracool red dwarf star in the constellation Cygnus, with just one tenth of the Sun's mass and 0.09% of its luminosity.
Characteristics
The planet's radius, as deduced from its transit depth, is 0.98 R⊕, making it similar to Earth in size.[2] The mass of SPECULOOS-3b has not been measured,[2] but the NASA Exoplanet Catalog estimated it at 0.894 M⊕.[6]
Discovery
Host star
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus[lower-alpha 1] |
| Right ascension | 20h 49m 27.44s[7] |
| Declination | +33° 36′ 50.985″[7] |
| Apparent magnitude (V) | 17.8 (estimate)[8] |
| Characteristics | |
| Evolutionary stage | Red dwarf |
| Spectral type | M6.5±0.5[2] |
| Apparent magnitude (B) | 19[7] |
| Apparent magnitude (R) | 16.4[7] |
| Apparent magnitude (G) | 15.379[9] |
| Apparent magnitude (J) | 11.5[10] |
| Apparent magnitude (H) | 10.867±0.021[7] |
| Apparent magnitude (K) | 10.54[10] |
| Astrometry | |
| Proper motion (μ) | RA: –207.809[9] mas/yr Dec.: –412.215[9] mas/yr |
| Parallax (π) | 59.7 ± 0.04[9] mas |
| Distance | 54.63 ± 0.04 ly (16.75 ± 0.01 pc) |
| Details[2] | |
| Mass | 0.1009±0.0024 M☉ |
| Radius | 0.123±0.0022 R☉ |
| Luminosity | 0.000835±0.000019 L☉ |
| Surface gravity (log g) | 5.265±0.014 cgs |
| Temperature | 2800±29 K |
| Metallicity [Fe/H] | 0.07±0.1 dex |
| Rotation | 1.34±0.14 d |
| Rotational velocity (v sin i) | 4.8±0.5 km/s |
| Age | 6.6+1.8 −2.4 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
LSPM J2049+3336, also known as SPECULOOS-3, is a red dwarf star (spectral type M6.5)[2] located in the constellation Cygnus.[lower-alpha 2] 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).[2]
The stellar radius, computed using the Stefan–Boltzmann law, is 0.134 R☉ (93,000 kilometres).[2] This makes SPECULOOS-3 the second-smallest star known to host a transiting planet, just marginally larger than TRAPPIST-1,[2] and is similar to that of Jupiter.[4] Its apparent magnitude is estimated at 17.8,[8] which is too faint to be seen with the naked eye. The star is estimated to be 6.6 billion years old (with large margins of error), and has a projected rotational period larger than 1.34 days, spinning at a velocity of 4.8 km/s.[2]
LSPM J2049+3336 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.[8] Its trigonometric parallax was first measured in 2014 at 67.5±1.7 mas, translating into a distance of 14.8 parsecs (48.27 ly).[10] Gaia Data Release 3 (2023) published a parallax of 59.7 milliarcseconds, translating into a distance of 16.75 parsecs (54.6 ly).[9]
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 longer than the Sun, with lifespans longer than 100 billion years.[3]
Notes
References
- ↑ Template:Cite EPE
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 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: 1–14. doi:10.1038/s41550-024-02271-2. ISSN 2397-3366.
- ↑ 3.0 3.1 "Discovery Alert: An Earth-sized World and Its Ultra-cool Star - NASA Science". science.nasa.gov. Retrieved 2024-05-26.
- ↑ 4.0 4.1 Hill, Samantha (2024-05-16). "Found: An Earth-sized exoplanet named SPECULOOS-3 b". Astronomy Magazine. Retrieved 2024-05-26.
- ↑ "Astronomers discover new Earth-sized world orbiting an ultra-cool star". phys.org. May 15, 2024. Retrieved 2024-05-26.
- ↑ "SPECULOOS-3 b - NASA Science". science.nasa.gov. Retrieved 2024-05-26.
- ↑ 7.0 7.1 7.2 7.3 7.4 "LSPM J2049+3336". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved May 26, 2024.
- ↑ 8.0 8.1 8.2 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: 1483–1522. doi:10.1086/427854. ISSN 0004-6256. SPECULOOS-3's database entry at VizieR.
- ↑ 9.0 9.1 9.2 9.3 Vallenari, A.; et al. (Gaia Collaboration) (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. arXiv:2208.00211. doi:10.1051/0004-6361/202243940. Gaia DR3 record for this source at VizieR.
- ↑ 10.0 10.1 10.2 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: 156. doi:10.1088/0004-637X/784/2/156. ISSN 0004-637X. SPECULOOS-3's database entry at VizieR.
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