Astronomy:TOI 700

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Short description: Red dwarf in the constellation Dorado
TOI 700
PIA23407-TOI700-PlanetarySystem.jpg
TOI planetary system
Credit: NASA's Goddard Space Flight Center
Observation data
Equinox J2000.0]] (ICRS)
Constellation Dorado[1][2]
Right ascension  06h 28m 22.97s[3]
Declination −65° 34′ 43.01″[3]
Apparent magnitude (V) 13.10±0.01[4]
Characteristics
Evolutionary stage Main sequence
Spectral type M2V[4]
Astrometry
Radial velocity (Rv)-4.4±0.1[4] km/s
Proper motion (μ) RA: -102.750±0.051[5] mas/yr
Dec.: 161.805±0.060[5] mas/yr
Parallax (π)32.0980 ± 0.0211[5] mas
Distance101.61 ± 0.07 ly
(31.15 ± 0.02 pc)
Details
Mass0.416 ± 0.010[4] M☉
Radius0.420 ± 0.031[4] R☉
Luminosity0.0233 ± 0.0011[4] L☉
Surface gravity (log g)4.81 ± 0.06[4] cgs
Temperature3480 ± 135[4] K
Metallicity [Fe/H]-0.07 ± 0.11[4] dex
Rotation54.0 ± 0.8[4] d
Age>1.5[4] Gyr
Other designations
TIC 150428135, UCAC3 49-21611, 2MASS J06282325-6534456, WISE J062823.05-653443.7, APASS 31812705, Gaia DR2 5284517766615492736
Database references
SIMBADdata
Extrasolar Planets
Encyclopaedia		data

TOI 700 is a red dwarf 101.4 light-years away from Earth[3][5] located in the Dorado constellation that hosts TOI 700 d, the first Earth-sized exoplanet in the habitable zone discovered by the Transiting Exoplanet Survey Satellite (TESS).[1][2][6]

Nomenclature and history

The acronym "TOI" refers to stars and exoplanets studied by TESS, and is short for: "Transiting Exoplanet Survey Satellite Object of Interest".

Stellar characteristics

TOI 700 is a red dwarf of spectral class M that is 40% the mass, 40% the radius and 55% of the temperature of the Sun.[6] 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.[4]

Planetary system

Artwork of exoplanet TOI 700 d

Three exoplanets have been detected by TESS to be orbiting the host star TOI 700. All three exoplanets may be tidally locked to TOI 700.[6]

Three papers describe the validation of the planetary system, the follow-up observations of TOI 700 d with the Spitzer Space Telescope and the characterization of TOI 700 d.[4][7][8]

The composition of planets b and d is more likely rocky and the composition of planet c is more likely similar to that of Neptune.[4]

The two inner planets might have grown faster and accreted significant gaseous envelopes, but the outer planet formed more slowly and accreted less gas. The innermost planet may later have lost its envelope due to photoevaporation. Another scenario that could explain the arrangement of densities in this system is long-term planetary migration. Planet c might have migrated inwards, but this scenario is more plausible if future studies show that planet c is significantly more massive than planet b or d.[4]

TOI 700 d lies in the habitable zone. It receives 35 times more EUV photons than Earth, but also 50 times less than TRAPPIST-1 e. The host star has low stellar activity. The atmosphere of a planet with an Earth-like pressure would survive for longer than 1 Gyr.[4] Simulations of the planet have shown that TOI 700 d is a robust candidate for a habitable world. The simulated spectral feature depths from transmission spectra and the peak flux and variations from synthesized phase curves do not exceed 10 ppm. This will likely prohibit JWST from characterizing the atmosphere of TOI 700 d.[8]

In November 2021, a fourth possible planet, Earth-sized and receiving approximately 49% more flux than TOI-700 d from TOI-700, was found at the inner edge of the habitable zone of TOI-700.[9]

The system is near (but not in) orbital resonance: from planets b to d, period ratios are approximately 5:8, 4:7, 3:4.

Hypothetical other, outer (beyond orbit of TOI-700d), cold celestial bodies in this system almost certainly don't transit from humans' path of view. However, they may be detectable by precise HARPS or ESPRESSO RV measurements: for example, mini-neptune with 60.114-day (5:8 resonance with d) "year" and mass of 8 Earth will be clearly seen in ESPRESSO data, having semi-amplitude of emission line shift about 2.37 m/s - comparable to excepted 2.9 m/s for planet c. Ever lower-mass (4.4 x Earth) and longer-period (89.563 days, 1.5 times of previous case) one could still produce distinguishable sinusoid (1.14 m/s) in more rich and longer-time dataset.

The TOI 700 planetary system[4][9]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b 1.07+0.80
−0.43 M⊕ 		0.0637+0.0064
−0.0060 		9.97701+0.00024
−0.00028 		— 89.67+0.23
−0.32° 		1.010+0.094
−0.087 R⊕
c 7.48+5.89
−3.30 M⊕ 		0.0925+0.0088
−0.0083 		16.051098+0.000089
−0.000092 		— 88.90+0.08
−0.11° 		2.63+0.24
−0.23 R⊕
e (unconfirmed) — 0.135 27.809371+0.000026
−0.000026 		— ≈89° 0.95 R⊕
d 1.72+1.29
−0.63 M⊕ 		0.163±0.015 37.4260+0.0007
−0.0010 		— 89.73+0.15
−0.12° 		1.19±0.11 R⊕

File:NASA-TESS-FirstEarthSizeExoplanetInHabitableZone-TOI700d-20200106.webm

See also


References

  1. ↑ 1.0 1.1 Andreolo, Claire; Cofield, Calla; Kazmierczak, Jeanette (6 January 2020). "NASA Planet Hunter Finds Earth-Size Habitable-Zone World". NASA. https://www.jpl.nasa.gov/news/news.php?feature=7569. 
  2. ↑ 2.0 2.1 Garner, Rob (6 January 2020). "NASA Planet Hunter Finds Earth-Size Habitable-Zone World". NASA. https://www.nasa.gov/feature/goddard/2020/nasa-planet-hunter-finds-its-1st-earth-size-habitable-zone-world. 
  3. ↑ 3.0 3.1 3.2 "ExoFOP TIC 150428135". https://exofop.ipac.caltech.edu/tess/target.php?id=150428135. 
  4. ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 4.15 4.16 Gilbert, Emily A.; Barclay, Thomas; Schlieder, Joshua E.; Quintana, Elisa V.; Hord, Benjamin J.; Kostov, Veselin B.; Lopez, Eric D.; Rowe, Jason F. et al. (2020-01-03). "The First Habitable Zone Earth-sized Planet from TESS. I: Validation of the TOI-700 System". The Astronomical Journal 160 (3): 116. doi:10.3847/1538-3881/aba4b2. Bibcode: 2020AJ....160..116G. 
  5. ↑ 5.0 5.1 5.2 5.3 Gaia Collaboration (2018-08-01). "Gaia Data Release 2 - Summary of the contents and survey properties" (in en). Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. ISSN 0004-6361. Bibcode: 2018A&A...616A...1G. 
  6. ↑ 6.0 6.1 6.2 Wall, Mike (6 January 2020). "NASA's TESS Planet Hunter Finds Its 1st Earth-Size World in 'Habitable Zone'". Space.com. https://www.space.com/nasa-tess-first-earth-size-habitable-exoplanet-toi-700d.html. 
  7. ↑ Rodriguez, Joseph E.; Vanderburg, Andrew; Zieba, Sebastian; Kreidberg, Laura; Morley, Caroline V.; Kane, Stephen R.; Spencer, Alton; Quinn, Samuel N. et al. (2020-01-03). "The First Habitable Zone Earth-Sized Planet From TESS II: Spitzer Confirms TOI-700 d". The Astronomical Journal 160 (3): 117. doi:10.3847/1538-3881/aba4b3. Bibcode: 2020AJ....160..117R. 
  8. ↑ 8.0 8.1 Suissa, Gabrielle; Wolf, Eric T.; Kopparapu, Ravi kumar; Villanueva, Geronimo L.; Fauchez, Thomas; Mandell, Avi M.; Arney, Giada; Gilbert, Emily A. et al. (2020-01-03). "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. doi:10.3847/1538-3881/aba4b4. Bibcode: 2020AJ....160..118S. 
  9. ↑ 9.0 9.1 "ExoFOP TIC 150428135". https://exofop.ipac.caltech.edu/tess/target.php?id=150428135. 

External links

Coordinates: Sky map 06h 28m 22.97s, −65° 34′ 43.01″




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