GJ 3929
{{Short description|Red dwarf star in the constellation Corona Borealis}}
{{Starbox begin}}
{{Starbox image
|image=300px
|caption=Artist's impression and size comparison of the two planets in the GJ 3929 system with Earth
}}
{{Starbox observe
|epoch=J2000
|constell=Corona Borealis{{cite constellation|GJ 3929}}
|pronounce=
}}
{{Starbox character
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{{Starbox astrometry
|prop_mo_ra=−143.059
|prop_mo_dec=+318.120
|parallax=63.1727
|p_error=0.038
|parallax_footnote={{cite Gaia DR3|1372215976327300480}}
}}
{{Starbox detail
|mass={{Val|0.313|0.027|0.022}}
|metal_fe={{val|-0.02|0.12}}
|radius={{val|0.32|0.01}}
|rotational_velocity={{val|2|p=<}}
|luminosity={{val|0.0109|0.0005|0.0004}}
|temperature={{val|3384|88|fmt=commas}}
|gravity={{val|4.89|0.05}}
|age_gyr=2.2 – 11.2{{efn|The quoted value of {{val|7.1|4.1|4.9}} has very high margins of error.|name=Error}}
|rotation={{val|122|13|ul=day}}
}}
{{Starbox catalog
|names=TOI-2013, TIC 188589164, 2MASS J15581883+3524236, Gaia DR3 1372215976327300480, G 180-18
}}
{{Starbox reference
|Simbad=G+180-18
|ARICNS=
}}
{{Starbox end}}
GJ 3929, also known as Gliese 3929 and TOI-2013, is a red dwarf star located 51.6 light-years from Earth, in the constellation Corona Borealis.{{Cite web |title=★ Gliese 3929 |url=https://www.stellarcatalog.com/stars/gliese-3929 |access-date=2024-01-01 |website=Stellar Catalog |language=en}} With an apparent magnitude of 12, it is not visible to the naked eye. In 2022, two exoplanets were detected orbiting the star.{{Cite journal |last1=Kemmer |first1=J. |last2=Dreizler |first2=S. |last3=Kossakowski |first3=D. |last4=Stock |first4=S. |last5=Quirrenbach |first5=A. |last6=Caballero |first6=J. A. |last7=Amado |first7=P. J. |last8=Collins |first8=K. A. |last9=Espinoza |first9=N. |last10=Herrero |first10=E. |last11=Jenkins |first11=J. M. |last12=Latham |first12=D. W. |last13=Lillo-Box |first13=J. |last14=Narita |first14=N. |last15=Pallé |first15=E. |date=2022-03-01 |title=Discovery and mass measurement of the hot, transiting, Earth-sized planet, GJ 3929 b |url=https://www.aanda.org/articles/aa/abs/2022/03/aa42653-21/aa42653-21.html |journal=Astronomy & Astrophysics |language=en |volume=659 |pages=A17 |doi=10.1051/0004-6361/202142653 |arxiv=2202.00970 |bibcode=2022A&A...659A..17K |issn=0004-6361}}
Characteristics
GJ 3929 is a red dwarf of spectral type M3.5V, having a radius of {{val|0.32|0.01|ul=Solar radius}}, a mass of {{val|0.313 |0.027|0.022|ul=Solar mass}} and a temperature of {{Val|3384|88|ul=K}}. With an apparent magnitude of 12.7,{{Cite web |title=GJ 3929 {{!}} NASA Exoplanet Archive |url=https://exoplanetarchive.ipac.caltech.edu/overview/GJ%203929 |access-date=2024-01-03 |website=exoplanetarchive.ipac.caltech.edu}} it cannot be visible with the naked eye, neither with a small telescope. It has no companion stars. The age of GJ 3929 is estimated at 2.2 to 12.2 billion years.
The star is located in the northern hemisphere, approximately 50 light years from Earth, in the direction of the constellation Corona Borealis. Its closest neighbor is the red dwarf G 179–57, located at a distance of 3.9 light years.
| class="wikitable unsortable"
!Name !Distance {{nowrap|(light-years)}} |
| G 179-57
|3.9 |
| LP 224-38
|5.2 |
| Ross 640
|5.6 |
| Rho Coronae Borealis
|5.9 |
| Gliese 611
|5.9 |
Planetary system
In 2022, two exoplanets were detected orbiting around GJ 3929. The innermost, GJ 3929 b, is a rocky planet just 9% larger than Earth, while the outermost, GJ 3929 c, is a sub-Neptune with 5.7 times the mass of Earth.{{Cite journal |last1=Beard |first1=Corey |last2=Robertson |first2=Paul |last3=Kanodia |first3=Shubham |last4=Lubin |first4=Jack |last5=Cañas |first5=Caleb I. |last6=Gupta |first6=Arvind F. |last7=Holcomb |first7=Rae |last8=Jones |first8=Sinclaire |last9=Libby-Roberts |first9=Jessica E. |last10=Lin |first10=Andrea S. J. |last11=Mahadevan |first11=Suvrath |last12=Stefánsson |first12=Guðmundur |last13=Bender |first13=Chad F. |last14=Blake |first14=Cullen H. |last15=Cochran |first15=William D. |date=2022-09-01 |title=GJ 3929: High Precision Photometric and Doppler Characterization of an Exo-Venus and its Hot, Mini-Neptune-mass Companion |journal=The Astrophysical Journal |volume=936 |issue=1 |pages=55 |doi=10.3847/1538-4357/ac8480 |doi-access=free |arxiv=2207.10672 |bibcode=2022ApJ...936...55B |issn=0004-637X}} Both planets orbit below the star's habitable zone.{{Cite web |title=Open Exoplanet Catalogue - GJ 3929 b |url=https://www.openexoplanetcatalogue.com/planet/GJ%203929%20b/ |access-date=2024-01-02 |website=www.openexoplanetcatalogue.com}}
{{OrbitboxPlanet begin|table_ref=|name=GJ 3929}}
{{OrbitboxPlanet|exoplanet=b|mass_earth={{val|1.75|0.45}}|radius_earth={{val|1.09|0.04}}|period={{val|2.616}}|semimajor={{val|0.0252|0.0005}}|inclination={{Nowrap|88.442°{{±|0.008}}}}|eccentricity=0 (fixed)}}
{{OrbitboxPlanet|exoplanet=c|mass_earth=>{{val|5.71|0.94}}|radius_earth=|period={{val|15.04|0.03}}|semimajor={{val|0.081|0.002}}|inclination=|eccentricity=0 (fixed)}}
{{Orbitbox end}}
= GJ 3929 b =
{{Main article|GJ 3929 b}}
The innermost planet, GJ 3929 b (TOI-2013 b), is an Earth-sized planet discovered by the transit method. Orbiting its star at a distance of {{Convert|0.0252|AU|km}}, the planet is located in its star's Venus zone, and completes a revolution every 2 days and 15 hours. The planet's equilibrium temperature is calculated at {{Convert|568|K|C}}, and it receives a planetary insolation 17 times greater than what the Earth receives from the Sun.
The planet's mass is calculated at {{val|1.75|0.45|ul=Earth mass}} according to photometric observations using the NEID spectrometer. Observations using the ARCTIC imager, plus photometry from TESS and LCOGT, constrained the planet's radius to {{val|1.09|0.04|ul=Earth radius}}. This radius makes GJ 3929 b very similar to Earth in terms of size.
Due to the apparent brightness of the host star, and its small size, GJ 3929 b is an excellent planet for atmospheric study with the James Webb Space Telescope.
It was discovered by a team of astronomers led by Jonas Kemmer.{{Cite web |title=Hot Earth-sized exoplanet detected with TESS |url=https://phys.org/news/2022-02-hot-earth-sized-exoplanet-tess.html |access-date=2024-01-04 |website=phys.org |language=en}} They reported an planetary transit signal in the host star's light curve. Subsequent observations, mainly with the CARMENES spectrograph, revealed that this transit signal is an orbiting exoplanet.
= {{vanchor|GJ 3929 c}} =
The outermost planet, GJ 3929 c (TOI-2013 c) is a Sub-Neptune discovered using the radial velocity method. It orbits its star at a distance of {{Convert|0.081|AU|km}}, 3 times further away than {{Nowrap|GJ 3929 b}}, but still below GJ 3929's habitable zone, completing an orbit every 15 days.
Its minimum mass is {{val|5.71|0.94|ul=Earth mass}}, while its radius is unknown. Estimates using mass-radius relationship derive a radius of 2.26 {{Earth radius|link=Y}}. Its equilibrium temperature is calculated at {{Convert|317|K|C}}, and it receives a planetary insolation 68% greater than what the Earth receives from the Sun.
GJ 3929 c was first identified in radial velocity data, which indicated the existence of another planet besides GJ 3929 b.{{Cite web |last=Cassese |first=Ben |date=2022-12-09 |title=Dotting the i's, Crossing the t's: Follow-Up of an Exo-Venus |url=https://aasnova.org/2022/12/09/dotting-the-is-crossing-the-ts-follow-up-of-an-exo-venus/ |access-date=2024-01-04 |website=AAS Nova |language=en-US}} Initially, it was just an exoplanet candidate, but it was later confirmed by a team led by Corey Beard. Because its orbital period (15 days) is far from its star's rotation period (122 days), it is unlikely that the radial velocity signal is actually an artifact of its parent star's activity and rotation.
See also
Notes
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References
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{{2022 in space}}
{{Corona Borealis}}
Category:M-type main-sequence stars