GJ 3929 b

GJ 3929 b
Discovery[1]
Discovered byKemmer et al.[2]
Discovery date2022
Transit
Designations
Gliese 3929 b, TOI 2013 b, G 180-18 b[3]
Orbital characteristics[4]
0.0252±0.0005 AU
Eccentricity0 (fixed)
2.616 d
Inclination88.442°±0.008°
StarGJ 3929
Physical characteristics[4]
1.09±0.04 R🜨
Mass1.75+0.44
−0.45 M🜨
Mean density
7.3±2.0 g/cm3
Temperature568±6 K (295 °C)

GJ 3929 b (Gliese 3929 b, TOI-2013 b) is a confirmed exoplanet located 52 light-years away orbiting the red dwarf star GJ 3929.[3] It is an Earth-sized planet, having a radius only 9% larger than that of Earth.[4] It orbits its star at a distance of 0.0252 astronomical units (3,770,000 km), being located in the Venus zone of its star, and completes one orbit around it every 2 days and 15 hours.[4] Because of the proximity of its star, and its low mass, GJ 3929 b is classified as a Venus-like planet, having an equilibrium temperature of around 300 °C and receiving planetary insolation 17 times more intense than Earth receives from the Sun.[4]

Characteristics

Size, mass and density

Initially, the radius of GJ 3929 b was calculated at 1.15±0.04 R🜨, and its mass at 1.21±0.42 M🜨, giving a density of 4.4±1.6 g/cm3.[5] Later, observations using the NEID spectrometer on the WIYN 3.5 m Telescope measured the planet's mass to be 1.75±0.45 M🜨; and observations using the ARCTIC imager, plus photometry from TESS and LCOGT, constrained the planet's radius to 1.09±0.04 R🜨, this time giving a higher density of 7.3±2 g/cm3 (about 33% larger than Earth's[a]).[4] The characteristics of this planet make it similar to Earth in terms of mass and radius.

Orbit

GJ 3929 b orbits its star at a distance of 0.0252 astronomical units (3,770,000 km), which makes it located in its host star's Venus zone, a region where rocky planets would have runaway greenhouse conditions like Venus.[4] GJ 3929 b completes an orbit around its star every 2 days, 14 hours and 47 minutes (2.616 days).[4]

As a terrestrial planet that orbits in the Venus zone of its star, GJ 3929 b classifies as a Venus-like planet, having a planetary equilibrium temperature of 295 °C and receiving planetary insolation 17 times greater than that of Earth receives from the Sun.[4]

Atmosphere

The high density of GJ 3929 b does not suggest a dense atmosphere.[4] Atmospheric scenarios such as a thin atmosphere of volatiles, a thin atmosphere of silicate enriched in refractory elements, or even no atmosphere at all are plausible.[4] Due to its proximity to its star, GJ 3929 b has probably already lost much of its atmosphere since its formation.[4]

GJ 3929 b is an excellent planet for atmospheric study with the James Webb Space Telescope.[4][5] The study of this planet's atmosphere can help reveal the evolutionary history of its planetary system, and provide more information about planetary formation models.[4]

Artist's impression and size comparison of the two planets in the GJ 3929 system with Earth

Discovery

GJ 3929 b was discovered by a team of astronomers led by Jonas Kermer, from the Heidelberg University in Germany.[2] They reported a transit signal identified in the host star (GJ 3929)'s light curve detected by NASA's Transiting Exoplanet Survey Satellite (TESS).[2] Afterwards, the planetary nature of this transit signal was confirmed using radial velocity observations with the CARMENES spectrograph, in addition to transit observations made with SAINT-EX and LCOGT.[5][2] The discovery was announced in 2022.[1]

The radial velocity observation with CARMENES also helped discover another planet in the planetary system, GJ 3929 c, a sub-Neptune detected by radial velocity.[5]

Host star

Main article: GJ 3929

GJ 3929 is a red dwarf of spectral type M3.5V[7] that is located 51.6 light years from Earth, in the constellation Corona Borealis.[3][note 1] This star is smaller, cooler and less luminous than the Sun, having a radius of 0.32 R☉, an effective temperature of 3,384 K (3,111 °C) and a luminosity equivalent to 1% of solar luminosity.[4] Its age is estimated between 2.2 and 11 billion years.[4]

The star also hosts another planet, called GJ 3929 c, a sub-Neptune orbits 3 times further than the innermost planet, at a distance of 0.081 astronomical units (12,100,000 km),[5] but still below the habitable zone.[8]

See also

Notes and references

  1. ^ a b "GJ 3929 b". NASA Exoplanet Exploration. Retrieved January 4, 2023.
  2. ^ a b c d "Hot Earth-sized exoplanet detected with TESS". phys.org. Retrieved 2024-01-04.
  3. ^ a b c "★ Gliese 3929". Stellar Catalog. Retrieved 2024-01-01.
  4. ^ a b c d e f g h i j k l m n o p Beard, Corey; Robertson, Paul; Kanodia, Shubham; Lubin, Jack; Cañas, Caleb I.; Gupta, Arvind F.; Holcomb, Rae; Jones, Sinclaire; Libby-Roberts, Jessica E.; Lin, Andrea S. J.; Mahadevan, Suvrath; Stefánsson, Guðmundur; Bender, Chad F.; Blake, Cullen H.; Cochran, William D. (2022-09-01). "GJ 3929: High Precision Photometric and Doppler Characterization of an Exo-Venus and its Hot, Mini-Neptune-mass Companion". The Astrophysical Journal. 936 (1): 55. arXiv:2207.10672. Bibcode:2022ApJ...936...55B. doi:10.3847/1538-4357/ac8480. ISSN 0004-637X.
  5. ^ a b c d e Kemmer, J.; Dreizler, S.; Kossakowski, D.; Stock, S.; Quirrenbach, A.; Caballero, J. A.; Amado, P. J.; Collins, K. A.; Espinoza, N.; Herrero, E.; Jenkins, J. M.; Latham, D. W.; Lillo-Box, J.; Narita, N.; Pallé, E. (2022-03-01). "Discovery and mass measurement of the hot, transiting, Earth-sized planet, GJ 3929 b". Astronomy & Astrophysics. 659: A17. arXiv:2202.00970. Bibcode:2022A&A...659A..17K. doi:10.1051/0004-6361/202142653. ISSN 0004-6361.
  6. ^ "Facts About Earth - NASA Science". science.nasa.gov. Retrieved 2023-12-04.
  7. ^ a b "G 180-18". SIMBAD. Retrieved January 4, 2023.
  8. ^ "Open Exoplanet Catalogue - GJ 3929 b". www.openexoplanetcatalogue.com. Retrieved 2024-01-03.
  1. ^ Obtained with a right ascension of 15h 58m 18.8s and a declination of +35° 24′ 24.3″[7] on this website.
  1. ^ The density of Earth is 5.513 g/cm³.[6]