Astronomy:Gliese 625

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Short description: Red dwarf in constellation of Draco
Gliese 625
Observation data
Equinox J2000.0]] (ICRS)
Constellation Draco[1]
Right ascension  16h 25m 24.62304s[2]
Declination +54° 18′ 14.7655″[2]
Apparent magnitude (V) 10.13[3]
Characteristics
Spectral type M1.5V[4]
B−V color index 1.591±0.027[3]
Astrometry
Radial velocity (Rv)−13.37±0.14[2] km/s
Proper motion (μ) RA: 432.230(19)[2] mas/yr
Dec.: −171.652(22)[2] mas/yr
Parallax (π)154.3503 ± 0.0161[2] mas
Distance21.131 ± 0.002 ly
(6.4788 ± 0.0007 pc)
Absolute magnitude (MV)11.06[3]
Details
Mass0.240±0.013[5] M☉
Radius0.255±0.034[5] R☉
Luminosity0.01482±0.00022[6] L☉
Surface gravity (log g)4.94±0.06[7] cgs
Temperature3,557±9[8] K
Metallicity [Fe/H]−0.401±0.005[8] dex
Rotation77.8±5.5 d[7]
Rotational velocity (v sin i)2.2±0.7[8] km/s
Other designations
GJ 625, HIP 80459, AC +54 1646, G 202-48, G 226-7, G 225-62, LSPM J1625+5418, NLTT 42804, PLX 3740.03, TYC 3878-1193-1, 2MASS J16252459+5418148[9]
Database references
SIMBADdata
Exoplanet Archivedata

GJ 625 (AC 54 1646-56) is a small red dwarf star with an exoplanetary companion in the northern constellation of Draco. The system is located at a distance of 21.1 light-years (6.4 parsecs) from the Sun based on parallax,[2] but is drifting closer with a radial velocity of −13 km/s.[8] It is too faint to be visible to the naked eye, having an apparent visual magnitude of 10.13[3] and an absolute magnitude of 11.06.[3]

This is an M-type main-sequence star with a stellar classification of M1.5V.[4] It is spinning slowly with a rotation period of roughly 78 days, and has a low magnetic activity level.[7] The star has about a quarter of the mass and size of the Sun,[5] and the metal content is 40% the abundances in the Sun's atmosphere. It is radiating just 1.5% of the luminosity of the Sun from its photosphere at an effective temperature of 3,557 K.[8]

Planetary system

On May 18, 2017, a planet was detected orbiting GJ 625 by the HARPS-N telescope. The planet, GJ 625 b, orbits near the inner edge of the optimistic circumstellar habitable zone of its star. Since M dwarf stars are cooler than the Sun, the planet may have potential for water despite its close proximity to its host star.[10] The discoverers speculate it may support liquid water, depending on atmospheric conditions.[7][11] Based on the habitable zone model of Kopparapu et al. 2013, the planet is not considered to be in the habitable zone as it would likely experience a runaway greenhouse effect, similar to Venus.[12][13][14][15]

Since the star is considered quiescent (having a low X-ray emission and flare rate), the radio emission from the system may be auroral in nature and coming from a short-period planet. Further observations will be needed to confirm this.[16]

The planet is roughly 3 times more massive than Earth and takes around two weeks to orbit its star, making its orbit around its star closer than the orbit of Mercury around the Sun.

The exoplanet was discovered using the HARPS-N Spectrograph.[10]

The orbital period of GJ 625 b is 14.63 days, with a semi-major axis of approximately 0.078 AU. It has a minimum mass of 2.82 times the mass of Earth and is classified as a super-Earth. The exoplanet was discovered by Suárez Mascareño in 2017 using the radial velocity method.[17][18]

The Gliese 625 planetary system[7]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b ≥2.82±0.51 M⊕ 0.078361+0.000044
−0.000046 		14.628+0.012
−0.013 		0.13+0.12
−0.09 		— —

References

  1. ↑ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific 99 (617): 695. doi:10.1086/132034. Bibcode: 1987PASP...99..695R  Constellation record for this object at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A. 
  4. ↑ 4.0 4.1 Alonso-Floriano, F. J. et al. (May 2015). "CARMENES input catalogue of M dwarfs. I. Low-resolution spectroscopy with CAFOS". Astronomy & Astrophysics 577: 19. doi:10.1051/0004-6361/201525803. A128. Bibcode: 2015A&A...577A.128A. 
  5. ↑ 5.0 5.1 5.2 Khata, Dhrimadri et al. (April 2020). "Understanding the physical properties of young M dwarfs: NIR spectroscopic studies". Monthly Notices of the Royal Astronomical Society 493 (3): 4533–4550. doi:10.1093/mnras/staa427. Bibcode: 2020MNRAS.493.4533K. 
  6. ↑ Schweitzer, A. et al. (May 2019). "The CARMENES search for exoplanets around M dwarfs. Different roads to radii and masses of the target stars". Astronomy & Astrophysics 625: 16. doi:10.1051/0004-6361/201834965. A68. Bibcode: 2019A&A...625A..68S.  VizieR entry
  7. ↑ 7.0 7.1 7.2 7.3 7.4 Suárez Mascareño, A. et al. (2017). "HADES RV Programme with HARPS-N at TNG. V. A super-Earth on the inner edge of the habitable zone of the nearby M dwarf GJ 625". Astronomy and Astrophysics 605: A92. doi:10.1051/0004-6361/201730957. Bibcode: 2017A&A...605A..92S. https://www.aanda.org/articles/aa/full_html/2017/09/aa30957-17/aa30957-17.html. Retrieved 2018-10-06. 
  8. ↑ 8.0 8.1 8.2 8.3 8.4 Fouqué, Pascal et al. (April 2018). "SPIRou Input Catalogue: global properties of 440 M dwarfs observed with ESPaDOnS at CFHT". Monthly Notices of the Royal Astronomical Society 475 (2): 1960–1986. doi:10.1093/mnras/stx3246. Bibcode: 2018MNRAS.475.1960F. 
  9. ↑ "G 202-48". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=G+202-48. 
  10. ↑ 10.0 10.1 "Discovery alert! A nearby super Earth - NASA Science" (in en-US). 2017-09-28. https://science.nasa.gov/universe/exoplanets/discovery-alert-a-nearby-super-earth/. 
  11. ↑ "GJ 625 b - NASA Science" (in en-US). 2019-04-22. https://science.nasa.gov/exoplanet-catalog/gj-625-b/. 
  12. ↑ Kopparapu, Ravi Kumar et al. (2013). "Habitable Zones Around Main-Sequence Stars: New Estimates". The Astrophysical Journal 765 (2): 131. doi:10.1088/0004-637X/765/2/131. Bibcode: 2013ApJ...765..131K. 
  13. ↑ Kopparapu, Ravi Kumar. "Calculation of Habitable Zones". https://personal.ems.psu.edu/~ruk15/planets/. 
  14. ↑ "GJ 625". http://hzgallery.org/3417_2.png. 
  15. ↑ LePage, Andrew (22 May 2017). "Habitable Planet Reality Check: Is GJ 625b a Super-Earth or a Super-Venus?". https://www.drewexmachina.com/2017/05/22/habitable-planet-reality-check-is-gj-625b-a-super-earth-or-a-super-venus/. 
  16. ↑ Pope, Benjamin J. S. et al. (September 2021). "The TESS View of LOFAR Radio-emitting Stars". The Astrophysical Journal Letters 919 (1): 8. doi:10.3847/2041-8213/ac230c. L10. Bibcode: 2021ApJ...919L..10P. 
  17. ↑ "GJ 625 | NASA Exoplanet Archive". https://exoplanetarchive.ipac.caltech.edu/overview/GJ%20625%20b#planet_GJ-625-b_collapsible. 
  18. ↑ Cowing, Keith (2017-05-18). "A Super-Earth on the Inner Edge of the Habitable Zone of the Nearby M-dwarf GJ 625" (in en-US). https://astrobiology.com/2017/05/a-super-earth-on-the-inner-edge-of-the-habitable-zone-of-the-nearby-m-dwarf-gj-625.html. 




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