TOI-700 d

TOI-700 d

Artistic simulation of TOI-700 d, depicted here as a possible ocean planet. The actual appearance of the planet is not currently known.
Discovery[1]
Discovered by	Emily Gilbert et al.
Discovery date	3 January 2020
Detection method	Transit
Orbital characteristics[2][3]
Semi-major axis	0.1610±0.0097 AU
Eccentricity	0.047+0.054 −0.030
Orbital period (sidereal)	37.42343+0.00021 −0.00013 d
Inclination	89.82°+0.12° −0.13°
Argument of perihelion	10°+120° −140°
Semi-amplitude	0.83+0.16 −0.18 m/s
Star	TOI-700
Physical characteristics
Mean radius	1.156+0.064 −0.063 R🜨[3]
Mass	2.40+0.49 −0.52 M🜨[3]
Mean density	8.47+2.45 −2.12 g/cm^3
Temperature	268.8+7.7 −7.6 K 268.8 K (−4.3 °C; 24.2 °F) (equilibrium)[4]

TOI-700 d is a dense, rocky, near-Earth-sized exoplanet orbiting within the habitable zone of the red dwarf TOI-700. It is located roughly 101.4 light-years (31.1 pc) away from Earth in the constellation of Dorado and is the outermost of 4 confirmed exoplanets around its star. The exoplanet is the first Earth-sized exoplanet in the habitable zone discovered by the Transiting Exoplanet Survey Satellite (TESS).^[5][6][7]

TOI-700 d orbits its star at a distance of 0.161 AU (24,100,000 km; 15,000,000 mi) from its host star with an orbital period of roughly 37.4 days and has a radius of around 1.19 times that of Earth. It has been estimated that the planet receives about 88% the energy that the Earth receives from the Sun.^[8]

It was discovered in early January 2020 by the Transiting Exoplanet Survey Satellite (TESS).

Physical characteristics

Mass, radius and temperature

TOI-700 d is slightly larger than Earth with a radius of about 1.16 R_🜨. However, it is significantly more massive at about 2.40 M_E with a density around 8.5 g/cm³. The planet's high density indicates a rocky composition with a higher fraction of iron than Earth and may be explained by high-energy giant impact events during its formation.^[3]

The planet has an equilibrium temperature would be about 268.8 K (−4.3 °C; 24.2 °F)^[4] and receives 88% as much sunlight as Earth does from the Sun.^[3] The surface temperature of TOI-700d is likely higher if it has an atmosphere. A small chance of a runaway greenhouse effect exists.^[9]

Host star

Main article: TOI-700

TOI-700 is a red dwarf of spectral class M that is about 40% the mass and radius, and very roughly 50% of the temperature of the Sun.^[7] The star is bright with low levels of stellar activity. Over the 11 sectors observed with TESS, the star does not show a single white-light flare. The low rotation rate is also an indicator of low stellar activity.^[1]

Orbit

TOI-700 d orbits its host star with an orbital period of 37.42 days. It has an orbital radius of about 0.161 AU (24.1 million km; 15.0 million mi), less than half of that of Mercury to the Sun in the Solar System. It receives about 88% of Earth's sunlight from its host star.

Habitability

Simulation of the planetary system of TOI-700 (center) and its habitable zone, with planet d orbiting within the inner edge.

TOI-700 d orbits in the habitable zone of its host star. The solar wind ram pressure and intensity of the interplanetary magnetic field are expected to be similar to the Earth's, therefore retention of the planetary atmosphere is likely.^[10][11] The presence of an extended hydrogen/helium envelope on TOI-700c indicates the star's high energy emission was insufficient to strip its atmosphere. Therefore TOI-700d, which receives less than half the insolation as c, may have been able to maintain a secondary high mean molecular weight atmosphere that's even less susceptible to photoevaporation.^[3]

History and discovery

TOI-700 d was discovered by a team of astronomers led by Emily Gilbert using the Transiting Exoplanet Survey Satellite (TESS) in early January 2020. This was the first Earth-sized exoplanet in the habitable zone discovered by TESS.^[12]

TOI-700 multiplanetary system (video; 3:16)

See also

• Kepler-62f
• Kepler-186f
• Kepler-442b
• LHS 1140 b
• List of potentially habitable exoplanets
• Proxima Centauri b
• TRAPPIST-1 e

References

1. Gilbert, Emily A.; Barclay, Thomas; Schlieder, Joshua E.; Quintana, Elisa V.; Hord, Benjamin J.; Kostov, Veselin B.; Lopez, Eric D.; Rowe, Jason F.; Hoffman, Kelsey; Walkowicz, Lucianne M.; Silverstein, Michele L. (3 January 2020). "The First Habitable Zone Earth-sized Planet from TESS. I: Validation of the TOI-700 System". The Astronomical Journal. 160 (3): 116. arXiv:2001.00952. Bibcode:2020AJ....160..116G. doi:10.3847/1538-3881/aba4b2. S2CID 209862554.
2. Gilbert, Emily A.; Vanderburg, Andrew; et al. (January 2023). "A Second Earth-Sized Planet in the Habitable Zone of the M Dwarf, TOI-700". The Astrophysical Journal Letters. 944 (2): L35. arXiv:2301.03617. Bibcode:2023ApJ...944L..35G. doi:10.3847/2041-8213/acb599. S2CID 255570018.
3. Gilbert, Emily; Burt, Jennifer; Barragán, Oscar; Siegel, Jared; Mascareño, Alejandro Suárez; Silva, André; Luque, Rafael; Rogers, James; Lee, Eve (31 October 2024), "Precise Masses Reveal that TOI-700 c is Low Density and TOI-700 d is Rocky", Research Square
4. Rodriguez, Joseph E.; Vanderburg, Andrew; Zieba, Sebastian; Kreidberg, Laura; Morley, Caroline V.; Kane, Stephen R.; Spencer, Alton; Quinn, Samuel N.; Eastman, Jason D.; Cloutier, Ryan; Huang, Chelsea X. (3 January 2020). "The First Habitable Zone Earth-Sized Planet from TESS. II: Spitzer Confirms TOI-700 d". The Astronomical Journal. 160 (3): 117. arXiv:2001.00954. Bibcode:2020AJ....160..117R. doi:10.3847/1538-3881/aba4b3. S2CID 209862553.
5. Andreolo, Claire; Cofield, Calla; Kazmierczak, Jeanette (6 January 2020). "NASA Planet Hunter Finds Earth-Size Habitable-Zone World". NASA. Retrieved 6 January 2020.
6. Garner, Rob (6 January 2020). "NASA Planet Hunter Finds Earth-Size Habitable-Zone World". NASA. Retrieved 6 January 2020.
7. Wall, Mike (6 January 2020). "NASA's TESS Planet Hunter Finds Its 1st Earth-Size World in 'Habitable Zone'". Space.com. Retrieved 6 January 2020.
8. "[VIDEO] TOI 700d : une planète de la taille de la Terre découverte dans une "zone habitable"". midilibre.fr (in French). Retrieved 17 April 2020.
9. Suissa, Gabrielle; Wolf, Eric T.; Kopparapu, Ravi Kumar; Villanueva, Geronimo L.; Fauchez, Thomas; Mandell, Avi M.; Arney, Giada; Gilbert, Emily A.; Schlieder, Joshua E.; Barclay, Thomas; Quintana, Elisa V.; Lopez, Eric; Rodriguez, Joseph E.; Vandenburg, Andrew (1 July 2020). "The First Habitable Zone Earth-sized Planet from TESS. III: Climate States and Characterization Prospects for TOI-700 d". The Astronomical Journal. 160 (3): 118. arXiv:2001.00955. Bibcode:2020AJ....160..118S. doi:10.3847/1538-3881/aba4b4. S2CID 209862275.
10. Cohen, O.; Garraffo, C.; Moschou, S.; Drake, J.; Alvarado-Gomez, J.; Glocer, A.; Fraschetti, F. (2020). "The Space Environment and Atmospheric Joule Heating of the Habitable Zone Exoplanet TOI 700 D". The Astrophysical Journal. 897 (1): 101. arXiv:2005.11587. Bibcode:2020ApJ...897..101C. doi:10.3847/1538-4357/ab9637. S2CID 218869952.
11. Dong, Chuanfei; Jin, Meng; Lingam, Manasvi (2020). "Atmospheric Escape from TOI-700 d: Venus versus Earth Analogs". The Astrophysical Journal. 896 (2): L24. arXiv:2005.13190. Bibcode:2020ApJ...896L..24D. doi:10.3847/2041-8213/ab982f. S2CID 219558481.
12. "NASA's TESS Planet Hunter Finds Its 1st Earth-Size World in 'Habitable Zone'". Space.com. 7 January 2020.

External links

• TESS – Official WebSite
• NASA Exoplanet Archive System Overview page for TOI-700 d
• ExoFOP TIC 150428135 TOI-700 in the Exoplanet Follow-up Observing Program website