Teegarden's Star b
Artist’s impression of Teegarden’s Star b
Discovery
Discovered byZechmeister et al.
Discovery siteCalar Alto Observatory
Discovery dateJune 2019
Orbital characteristics
0.0252+0.0008
−0.0009[1] AU
Eccentricity0+0.16
−0[1]
4.91±0.0014[1] d
StarTeegarden's Star[1]
Physical characteristics
Mass≥ 1.05+0.13
−0.12[1] MEarth
Temperature301 K (28 °C)

    Teegarden's Star b (also known as Teegarden b) is an exoplanet found orbiting within the habitable zone of Teegarden's Star, an M-type red dwarf 12.5 light years away from the Solar System. It has the highest Earth Similarity Index of any exoplanet found to-date.[2]: 106  Along with Teegarden's Star c, it is among the closest known potentially habitable exoplanets.[3][4]

    Discovery

    In July 2019, a team of more than 150 scientists led by Mathias Zechmeister published a peer-reviewed article in Astronomy & Astrophysics as part of the CARMENES survey supporting the existence of two candidate exoplanets orbiting Teegarden's Star.[1]

    Because of the alignment and faintness of Teegarden's Star, Doppler spectroscopy (also known as the radial velocity method) was necessary to detect possible exoplanets. This method detects exoplanets indirectly by observing their effects on a host star's radial velocity, the speed at which it is moving towards or away from the Earth. These radial velocity anomalies in turn produce doppler shifts observable with a spectrograph-equipped telescope of sufficient power.

    To accomplish this, the team used the CARMENES instrument on the 3.5-meter telescope of Spain's Calar Alto Observatory.[1][5] After three years of observation,[6] two periodic radial velocity signals emerged: one at 4.91 days (Teegarden's Star b) and another at 11.41 days (Teegarden's Star c).[1][7]

    Physical characteristics

    Mass and orbit

    Teegarden's Star b is the innermost known planet orbiting Teegarden's Star, with an orbital period of just 4.91 days. The planet's minimum mass is 1.05 Earth masses (MEarth); this value would be the true mass if the planet's orbit is not inclined from the Earth's perspective.[1] Because of this, Teegarden's Star b is likely to be rocky.[8] Astronomers estimate that Teegarden's Star b has a 60 percent chance of having liquid water, but only a 3 percent chance of having an atmosphere.[2]: 105–107 

    Host star

    Teegarden’s Star is a low-mass red dwarf, with a mass of around 9 percent the mass of the Sun's, and with a temperature of around 2,900 Kelvin (2,623 °C or 4,760 F). Due to the very low temperature and luminosity of Teegarden's Star it was only discovered in 2003, since it has an apparent magnitude of only 15.1 (and an absolute magnitude of 17.22). Like most red and brown dwarfs it emits most of its energy in the infrared spectrum. It is also older than the Sun, with an age of 8 billion years.

    Habitability

    Ross 128, an example of a quiet red dwarf that can support a habitable planet, like Teegarden's Star.

    Teegarden's Star b orbits within the habitable zone of its host star, meaning it is possible that its atmospheric composition could allow for stable liquid water on its surface, which could have also allowed the development of life.[7]

    See also

    References

      1. 1 2 3 4 5 6 7 8 9 10 Caballero, J. A.; Reiners, Ansgar; Ribas, I.; Dreizler, S.; Zechmeister, M.; et al. (12 June 2019). "The CARMENES search for exoplanets around M dwarfs. Two temperate Earth-mass planet candidates around Teegarden's Star" (PDF). Astronomy & Astrophysics. 627: A49. arXiv:1906.07196. Bibcode:2019A&A...627A..49Z. doi:10.1051/0004-6361/201935460. ISSN 0004-6361. S2CID 189999121.
      2. 1 2 Carroll, Michael (2020). Envisioning Exoplanets: Searching for Life in the Galaxy. Smithsonian Books. ISBN 978-1-58834-691-9.
      3. ↑ "The Habitable Exoplanets Catalog". Planetary Habitability Laboratory. University of Puerto Rico at Arecibo. Retrieved 26 April 2023.
      4. ↑ Suárez Mascareño, A.; González-Alvarez, E.; et al. (December 2022). "Two temperate Earth-mass planets orbiting the nearby star GJ 1002". Astronomy & Astrophysics. 670: A5. arXiv:2212.07332. Bibcode:2023A&A...670A...5S. doi:10.1051/0004-6361/202244991. S2CID 254353639.
      5. ↑ "CARMENES • Instrument".
      6. ↑ "Moreover, we have shown that the 4.9 d signal is stable over the three years of observations in period and amplitude."[1]: 8 
      7. 1 2 Cassella, Carly (June 19, 2019). "We Just Found 2 of The Most Earth-Like Exoplanets Yet, Only 12.5 Light Years Away". Science Alert.
      8. ↑ Chen, Jingjing; Kipping, David (2017). "Probabilistic Forecasting of the Masses and Radii of Other Worlds". The Astrophysical Journal. 834 (1): 17. arXiv:1603.08614. Bibcode:2017ApJ...834...17C. doi:10.3847/1538-4357/834/1/17. S2CID 119114880.
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