HD 63433

Last updated
HD 63433
Observation data
Epoch J2000       Equinox J2000
Constellation Gemini [note 1]
Right ascension 07h 49m 55.05s [1]
Declination 27° 21′ 47.45″ [1]
Apparent magnitude  (V)6.92 [2]
Characteristics
Evolutionary stage Main sequence [3]
Spectral type G5V [3]
Variable type BY Draconis [4] [5]
Astrometry
Radial velocity (Rv)−16.07±0.13 [2]  km/s
Proper motion (μ)RA: −10.0268±0.0846  mas/yr [2]
Dec.: −11.3143±0.0487  mas/yr [2]
Parallax (π)44.6848  mas [6]
Distance 73.035±0.073  ly
(22.4035±0.0225  pc) [2]
Absolute magnitude  (MV)5.19 [7]
Details [8]
Mass 0.99±0.03  M☉
Radius 0.912±0.034  R☉
Luminosity 0.753±0.026  L☉
Surface gravity (log g)4.52±0.05 [3]   cgs
Temperature 5640±74  K
Metallicity [Fe/H]0.03±0.05 [3]   dex
Rotation 6.45±0.05  d
Rotational velocity (v sin i)7.3±0.3 km/s
Age 414±23  Myr
Other designations
V377 Gem, BD+27°1490, HD  63433, HIP  38228, SAO  79729, PPM  98012, TOI-1726, TYC  1933-747-1, GSC  01933-00747, 2MASS J07495506+2721473 [9]
Database references
SIMBAD data

HD 63433 (TOI-1726, V377 Geminorum) is a G-type main sequence star located 73 light-years from Earth in the zodiacal constellation Gemini, [8] [note 1] visually close to the star Pollux. [6] It is classified as a Sun-like star, having a mass 99% similar and a size 91% similar to that of the Sun. [8] However, it is a much younger star, less than one tenth as old with an age of about 400 million years. [8] [lower-alpha 1] With an apparent magnitude of 6.9, it is not visible to the naked eye, but can be seen with a small telescope. [11] Based on its kinematic, rotational and lithium abundance properties, it is part of the Ursa Major Moving Group. [8] There are three exoplanets orbiting it, one is classified as an Earth-sized planet, while the two others are mini-Neptunes. [3]

Contents

Characteristics

HD 63433 is a Sun-like star, having a radius of 0.912  R☉ , a mass of 0.99  M☉ , an effective temperature of 5640  K and a spectral type G5V. [8] Its properties are quite similar to those of the Sun, which has a spectral type G2V and a temperature of 5772 K. [12] HD 63433, however, is much younger than the Sun, having an age of 414 million years, [8] just 9% of the solar age of 4.6 billion years. [10]

It is also a variable star, belonging to the class of BY Draconis variables, [4] [5] stars which have variations in their luminosity due to their rotation together with sunspots and other chromospheric activities. The brightness of the star varies by 0.05 magnitudes over a period of 6.46 days. [5] It has the variable-star designation V377 Geminorum. [6] [5]

With an apparent magnitude of 6.92m, [2] it is below the limit for naked-eye visibility, generally defined as 6.5m, [13] which would mean that this star is not visible to the naked eye, but easily visible using a small telescope [11] or binoculars. [14] Despite being faint, HD 63433 is actually the third-brightest star with transiting exoplanets confirmed by the Transiting Exoplanet Survey Satellite, with only Pi Mensae (5.65m) [15] and HR 858 (6.38m) [16] being brighter. [8] [17]

According to stellar kinematics, lithium abundance and stellar rotation, HD 63433 is part of the Ursa Major moving group. [8] It was initially identified as a possible member of this group by Gaidos (1998) [18] and included as a possible member in later analyses, until HD 63433's membership in this moving group was finally confirmed by Mann et al. in 2020. [8] As it is part of this moving group, its age is estimated at 414 ± 23 million years, the same as the group. [8]

It is located in the northern hemisphere, about 73 light-years from the Earth, in the constellation of Gemini. [11] It is visually close to Pollux, the brightest star in the constellation. [6] HD 63433 is predicted to approach within 7.33 light-years of the Sun in 1.33 million years. [19] That will make it one of the nearest stars to the Sun. Its closest neighbor is the orange dwarf HD 63991, located at a distance of 2.7 light years. [11]

Nearest stars to HD 63433 [11]
NameDistance

(light-years)

HD 639912.7
LSPM J0801+23426.1
HD 680179
BD+31 17819.1
G 90-529.2

Planetary system

The star HD 63433 is orbited by 3 exoplanets, all discovered by the transit method.

The first ones to be discovered, HD 63433 b and HD 63433 c, are mini-Neptunes [20] that were discovered in by Mann et al. in 2020 using the Transiting Exoplanet Survey Satellite. [21] In 2024, an additional planet was discovered, after an analysis of a transit signal detected by TESS. Named HD 63433 d, it is an Earth-sized planet. [22]

According to theoretical models, the compositions of the mini-Neptunes HD 63433 b and c are mostly silicate and water, with no iron dominance, surrounded by a gaseous envelope which, in the case of planet c, makes up around 2% of the planet. [20]

The planetary system of HD 63433 is quite young, at around 400 million years old, it is only 9.13% as old as the Solar System. [3] [22] [lower-alpha 2] HD 63433 d is also the smallest planet that is less than 500 million years old.

Temperature
comparisons		 HD 63433 b [20] HD 63433 c [20] HD 63433 d [3]
Global equilibrium temperature 769 – 967 K
496 – 694 °C
925 – 1281 °F		540 – 679 K
267 – 406 °C
513 – 763 °F		1040 K
767 °C
1413 °F
The HD 63433 planetary system [3] [20]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
d —0.0503±0.00274.210.16+0.36
−0.12		88.73±1 ° 1.073+0.046
−0.044  R🜨
b <21.76  M🜨 0.0719+0.0044
−0.0031		7.110.24+0.27
−0.18		—2.14+0.087
−0.069  R🜨
c 15.54±3.86  M🜨 0.1458±0.01520.550.161+0.014
−0.013		—2.692+0.108
−0.088  R🜨

HD 63433 b

The middle planet, HD 63433 b, is a mini-Neptune planet that was discovered together with HD 63433 c. [3] HD 63433 b is 2.14 times larger than Earth, [20] but is about 45% smaller than Neptune. [lower-alpha 3] The planet has an upper mass limit of 21.7  M🜨 , [20] which is 21% greater than the mass of Neptune (17.15  M🜨 [23] ). These values calculate an upper density limit of 13 g/cm3, [20] 2 times greater than that of Earth, [note 2] and similar to that of the chemical element Mercury. HD 63433 b orbits its parent star at a distance of 0.0719 astronomical units (10,760,000 km) – about 5 times closer than Mercury is to the Sun – and completes one revolution every 7 days and 3 hours. The relative proximity of its star makes it hot, with an equilibrium temperature between 769 and 967 Kelvin (496 and 694 °C). [20] [lower-alpha 4]

HD 63433 b was probably a mini-Neptune that later lost its atmosphere. [25] Some factors, such as the fact that no absorption of Ly-α was detected during its transit, and its mass-loss timescale being shorter than the age of the planetary system, indicate that it has already lost its primordial atmosphere, and could be a rocky planetary core. [25] However, if HD 63433 b were a rocky core, it would need to be unusually massive and, therefore, a water-rich composition in addition to an atmosphere with a high mean molecular weight could explain both the radius and the non-detection of the Lyα. [25]

HD 63433 c

The outermost planet, HD 63433 c, is a mini-Neptune planet discovered together with HD 63433 b. [8] It is 2.7 times larger than Earth, [20] but 30% smaller than the Solar System's ice giants, Neptune and Uranus. Being 15.5 times more massive than the Earth, [20] it is more massive than Uranus (14.54  M🜨 ), but still less massive than Neptune (17.15  M🜨 ). The density of HD 63433 c calculated at 4.6 g/cm3, slightly lower than that of Earth, [20] but greater than the densities of all gas giants in the Solar System.

Orbiting its star at a distance of 0.145 astronomical units (21,700,000 km) in a orbital period of 20 days, [20] it is the outermost planet in its planetary system, but still close to its star, making it a warm planet, with a planetary equilibrium temperature estimated between 267 and 406 °C. [20] [lower-alpha 5]

Due to the high radiation received from its star, the atmosphere of HD 63433 c, made up of hydrogen, is slowly being stripped away and escaping from the planet, like a hot air balloon. [26] The hot gas escapes into the space at a velocity of 50 km/s, forming a gas cocoon 12 times larger than the planet itself. [26] As its atmosphere evaporates, HD 63433 c will slowly become a super-Earth planet. [26]

HD 63433 d

HD 63433 d was the last planet to be discovered in the system, 4 years after planets b and c. [3] With a diameter of ~13,690 km, it is very similar to Earth in size, being only 7% larger, but its mass is currently unknown. [3] It is the innermost planet orbiting HD 63433, having a semi-major axis (mean distance from its star) of 0.0503 astronomical units (7,520,000 km) and an orbital period of just 4 days. [3] The extreme proximity to its star makes it extremely hot, having a daytime temperature estimated at 1,260 °C (2,300 °F), [3] [lower-alpha 6] hot enough to melt all the minerals present on its surface, [27] as well as being tidally locked, meaning that one half of the planet is always facing towards its star, while the other is always facing away from it. [28] [22] The planet also possibly lacks a substantial atmosphere. [3] [22] [27]

It is believed that the dayside of the planet, always facing its star due to tidal locking, is fully composed of lava due to the high surface temperature, [29] [22] in addition to possibly having volcanic activity. [30] [31] Meanwhile, the nightside of the planet, which never faces its star, may be the opposite, resembling Pluto with glaciers of frozen nitrogen. [32]

HD 63433 d was discovered in 2024, through an analysis of a transit observation made by the Transiting Exoplanet Survey Satellite (TESS). [22] As two other planets had already been discovered in the system, the transit signals of these objects were removed, thus revealing an additional transit signal that reappeared every 4.2 days. [22] [33] [3] Further investigation allowed researchers to confirm that this signal was from another orbiting exoplanet, now called HD 63433 d. [22] The discovery was announced on January 10, 2024, in The Astronomical Journal. [28] [32]

Scientific importance

The HD 63433 planetary system plays an important role in understanding the evolution of planetary systems in the first billion years after formation. [8] [3] As HD 63433 is relatively bright (6.9 m ) and close (73 ly away), its planets b and c can have their atmospheres characterized by the Hubble Space Telescope and James Webb Space Telescope. [25] This star is also a favorable target for studies of atmospheric mass loss in exoplanets, as it is a young and active star with close-in mini-Neptune planets, in addition to having a negative radial velocity (−16.07  km/s ). [25]

See also

Notes and references

  1. 1 2 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
  2. 1 2 3 4 5 6 "HD 63433 | NASA Exoplanet Archive". exoplanetarchive.ipac.caltech.edu. Retrieved 2024-01-13.
  3. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Capistrant, Benjamin K.; Soares-Furtado, Melinda; Vanderburg, Andrew; Jankowski, Alyssa; Mann, Andrew W.; Ross, Gabrielle; Srdoc, Gregor; Hinkel, Natalie R.; Becker, Juliette (2024-01-09), "TESS Hunt for Young and Maturing Exoplanets (THYME) XI: An Earth-sized Planet Orbiting a Nearby, Solar-like Host in the 400Myr Ursa Major Moving Group", The Astronomical Journal, 167 (2): 54, arXiv: 2401.04785 , Bibcode:2024AJ....167...54C, doi: 10.3847/1538-3881/ad1039
  4. 1 2 Notsu, Yuta; Honda, Satoshi; Maehara, Hiroyuki; Notsu, Shota; Namekata, Kosuke; Nogami, Daisaku; Shibata, Kazunari (2017-02-01). "Spectroscopic observations of active solar-analog stars having high X-ray luminosity, as a proxy of superflare stars". Publications of the Astronomical Society of Japan. 69 (1): 12. arXiv: 1611.03659 . doi:10.1093/pasj/psw116. ISSN   0004-6264.
  5. 1 2 3 4 "VSX : Detail for V0377 Gem". www.aavso.org. Retrieved 2024-01-21.
  6. 1 2 3 4 5 "HD 63433". simbad.cds.unistra.fr. Retrieved 2024-01-11.
  7. ↑ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv: 1108.4971 , Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID   119257644.
  8. 1 2 3 4 5 6 7 8 9 10 11 12 13 Mann, Andrew W.; Johnson, Marshall C.; Vanderburg, Andrew; Kraus, Adam L.; Rizzuto, Aaron C.; Wood, Mackenna L.; Bush, Jonathan L.; Rockcliffe, Keighley; Newton, Elisabeth R.; Latham, David W.; Mamajek, Eric E.; Zhou, George; Quinn, Samuel N.; Thao, Pa Chia; Benatti, Serena (2020-09-24). "TESS Hunt for Young and Maturing Exoplanets (THYME). III. A Two-planet System in the 400 Myr Ursa Major Group". The Astronomical Journal. 160 (4): 179. arXiv: 2005.00047 . Bibcode:2020AJ....160..179M. doi: 10.3847/1538-3881/abae64 . ISSN   0004-6256.
  9. ↑ "HD 63433". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2024-01-23.
  10. 1 2 Bonanno, A.; Schlattl, H.; Paterno`, L. (August 2002). "The age of the Sun and the relativistic corrections in the EOS". Astronomy & Astrophysics. 390 (3): 1115–1118. arXiv: astro-ph/0204331 . Bibcode:2002A&A...390.1115B. doi:10.1051/0004-6361:20020749. ISSN   0004-6361.
  11. 1 2 3 4 5 "★ HD 63433". Stellar Catalog. Retrieved 2024-01-11.
  12. ↑ "Sun Fact Sheet". nssdc.gsfc.nasa.gov. Retrieved 2024-01-11.
  13. ↑ Curtis, Heber Doust (1903-01-01). "On the limits of unaided vision". Lick Observatory Bulletin. 38: 67–69. Bibcode:1903LicOB...2...67C. doi:10.5479/ADS/bib/1903LicOB.2.67C. ISSN   0075-9317. S2CID   124815809.
  14. ↑ Siegel-Itzkovich, Judy (January 14, 2024). "Earth-sized exoplanet discovered in 'our solar backyard' by international team". The Jerusalem Post. Archived from the original on January 20, 2024. Retrieved January 20, 2024.
  15. ↑ Johnson, H. L.; Mitchell, R. I.; Iriarte, B.; Wisniewski, W. Z. (1966-01-01). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99–110. Bibcode:1966CoLPL...4...99J.
  16. ↑ Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000-03-01). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H. ISSN   0004-6361.
  17. ↑ "NASA Exoplanet Space Institute". exoplanetarchive.ipac.caltech.edu. Retrieved January 15, 2024.
  18. ↑ Gaidos, Eric J. (November 1998). "Nearby Young Solar Analogs. I. Catalog and Stellar Characteristics". Publications of the Astronomical Society of the Pacific. 110 (753): 1259–1276. Bibcode:1998PASP..110.1259G. doi:10.1086/316251. ISSN   0004-6280.
  19. ↑ Bailer-Jones, C.A.L.; et al. (2018), "New stellar encounters discovered in the second Gaia data release", Astronomy & Astrophysics, 616: A37, arXiv: 1805.07581 , Bibcode:2018A&A...616A..37B, doi:10.1051/0004-6361/201833456, S2CID   56269929.
  20. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Mallorquín, M.; Béjar, V. J. S.; Lodieu, N.; Osorio, M. R. Zapatero; Tabernero, H.; Mascareño, A. Suárez; Zechmeister, M.; Luque, R.; Pallé, E.; Montes, D. (2023-03-01). "Dynamical masses of two young transiting sub-Neptunes orbiting HD 63433". Astronomy & Astrophysics. 671: A163. arXiv: 2303.15411 . Bibcode:2023A&A...671A.163M. doi:10.1051/0004-6361/202245397. ISSN   0004-6361.
  21. ↑ "HD 63433". Open Exoplanet Catalogue. Archived from the original on January 14, 2024. Retrieved January 14, 2024.
  22. 1 2 3 4 5 6 7 8 Gohd, Chelsea (January 11, 2024). "Discovery Alert: Earth-sized Planet Has a 'Lava Hemisphere'". science.nasa.gov. Retrieved January 10, 2024.
  23. 1 2 "Neptune Fact Sheet". nssdc.gsfc.nasa.gov. Retrieved January 24, 2024.
  24. ↑ "Facts About Earth - NASA Science". science.nasa.gov. Retrieved 2023-12-04.
  25. 1 2 3 4 5 Zhang, Michael; Knutson, Heather A.; Wang, Lile; Dai, Fei; Santos, Leonardo A. dos; Fossati, Luca; Henry, Gregory W.; Ehrenreich, David; Alibert, Yann; Hoyer, Sergio; Wilson, Thomas G.; Bonfanti, Andrea (January 2022). "Detection of Ongoing Mass Loss from HD 63433c, a Young Mini-Neptune". The Astronomical Journal. 163 (2): 68. arXiv: 2106.05273 . Bibcode:2022AJ....163...68Z. doi: 10.3847/1538-3881/ac3f3b . ISSN   1538-3881.
  26. 1 2 3 "Puffy Planets Lose Atmospheres, Become Super-Earths". hubblesite.org. February 3, 2022. Retrieved January 19, 2024.
  27. 1 2 Thomson, Jess (January 12, 2024). "Hellish World With 2,294 F 'Lava Hemisphere' Discovered by NASA". Newsweek. Retrieved January 23, 2024.
  28. 1 2 Robert, Lea (January 12, 2024). "Newfound Earth-size exoplanet has a scorching-hot lava side". Space. Archived from the original on January 12, 2024. Retrieved January 12, 2024.
  29. ↑ Gough, Evan (January 12, 2024). "Half of this Exoplanet is Covered in Lava". Universe Today.
  30. ↑ Staff, Buzz (16 January 2024). "NASA Telescope Discovers Half-Lava Exoplanet Of Same Size As Earth". News18. Retrieved January 16, 2024.
  31. ↑ Whitwam, Ryan (January 15, 2024). "Astronomers Discover Earth-Sized Planet That's Half Lava". ExtremeTech. Retrieved January 17, 2024.
  32. 1 2 Szondy, David (January 11, 2024). "Tidally locked exo-Earth has a lava ocean hemisphere". New Atlas. Archived from the original on January 16, 2024. Retrieved January 14, 2024.
  33. ↑ "'Extra hot and young' Earth-sized exoplanet with a 'lava hemisphere' discovered". wionews.com. January 17, 2024.
  1. ↑ The age of the Sun is around 4.6 billion years. [10]
  2. ↑ The age of the Solar System is 4.532 billion years.
  3. ↑ Neptune is 3.883 times larger than Earth. [23]
  4. ↑ Assuming albedos of 0.6 and 0 respectively.
  5. ↑ Assuming albedos of 0.6 and 0 respectively.
  6. ↑ Assuming an albedo of 0, similar to the measured albedo of TRAPPIST-1b.
  1. 1 2 Obtained with a right ascension of 07h 49m 55.06s and a declination of 27° 21′ 47.5″ [6] on this website.
  2. ↑ The density of Earth is 5.513 g/cm3. [24]

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GJ 3929 b is a confirmed exoplanet located 52 light-years away orbiting the red dwarf star GJ 3929. It is an Earth-sized planet, having a radius only 9% larger than that of Earth. 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. 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.

HD 63433 d is a confirmed exoplanet orbiting HD 63433, a Sun-like star located 73 light-years away in the constellation Gemini. It was the third exoplanet to be discovered in orbit around this star; the other two were HD 63433 b and c, discovered in 2020. Its radius is measured at around 1.1 R🜨, which makes it similar to the Earth in size. Orbiting its star at a distance of 0.0503 astronomical units (7,520,000 km), it is the innermost planet orbiting HD 63433, and completes an orbit around it just every 4 days. Due to the proximity of its star, the planet is scorching hot, having a temperature estimated at 1260 °C at daytime. The proximity of its star also causes it to be tidally locked.

HD 63433 c is a mini-Neptune exoplanet orbiting the Sun-like star HD 63433. It is the outermost planet in its planetary system, being located 0.1448 astronomical units (21,660,000 km) from its star, and completing one orbit every 21 days. Despite being the outermost planet in the system, it is still located close to its star, meaning that its temperature is hot, being estimated between 267 and 406 °C. HD 63433 c is about 2.7 times larger than Earth and 15.5 times more massive, but still smaller and less massive than Neptune. In 2022, a study showed that its atmosphere, made up of hydrogen, is being evaporated by the strong radiation from its star, causing it to slowly turn into a super-Earth planet.

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