Ross 128

Ross 128

Artist's impression of the planet Ross 128 b, with the star Ross 128 visible in the background[1]
Credit: European Southern Observatory
Observation data
Epoch J2000      Equinox J2000
Constellation Virgo
Right ascension 11h 47m 44.39727s[2]
Declination +00° 48′ 16.4003″[2]
Apparent magnitude (V) 11.13[3]
Characteristics
Evolutionary stage Main sequence
Spectral type M4V[4]
U−B color index +2.685[5]
B−V color index +1.59[6]
Variable type Flare star[7]
Astrometry
Radial velocity (Rv)−31.0[8][9] km/s
Proper motion (μ) RA: 607.299(34) mas/yr[2]
Dec.: −1223.028(23) mas/yr[2]
Parallax (π)296.3053 ± 0.0302 mas[2]
Distance11.007 ± 0.001 ly
(3.3749 ± 0.0003 pc)
Absolute magnitude (MV)13.53[3]
Details
Mass0.176±0.004[10] M☉
Radius0.198±0.007[10] R☉
Luminosity (bolometric)0.00366 ± 0.00005[10] L☉
Surface gravity (log g)3.40[11] cgs
Temperature3,189+55
−53[10] K
Metallicity [Fe/H]−0.02±0.08[12] dex
Rotation101–223 days[13]
Rotational velocity (v sin i)2.1±1.0[14] km/s
Age5.0[15] Gyr
Other designations
FI Vir, GJ 447, HIP 57548, G 10-50, LFT 852, LHS 315, LSPM J1147+0048, LTT 13240, PLX 2730, Ross 128, Vyssotsky 286[16]
Database references
SIMBADdata
Ross 128 is located in the constellation Virgo.
Ross 128 is located in the constellation Virgo.
 Ross 128
Location of Ross 128 in the constellation Virgo

Ross 128 is a red dwarf star in the equatorial zodiac constellation of Virgo, near β Virginis. The apparent magnitude of Ross 128 is 11.13,[3] which is too faint to be seen with the unaided eye. Based upon parallax measurements, the distance of this star from Earth is 11.007 light-years (3.375 parsecs), making it the twelfth closest stellar system to the Solar System. It was first cataloged in 1926 by American astronomer Frank Elmore Ross.[17]

Properties

Distances of the nearest stars from 20,000 years ago until 80,000 years in the future

This low-mass star has a stellar classification of M4 V,[4] which places it among the category of stars known as red dwarfs. It has about 18%[10] of the mass of the Sun and 20%[10] of the Sun's radius, but generates energy so slowly that it has only 0.033% of the Sun's visible luminosity;[3] however, most of the energy being radiated by the star is in the infrared band, with the bolometric luminosity being equal to 0.37% of solar.[10] This energy is being radiated from the star's outer atmosphere at an effective temperature of 3,180 K.[4] This gives it the cool orange-red glow of an M-type star.

Ross 128 is an old disk star, which means it has a low abundance of elements other than hydrogen and helium, what astronomers term the star's metallicity, and it orbits near the plane of the Milky Way galaxy.[18] The star lacks a strong excess of infrared radiation. An infrared excess is usually an indicator of a dust ring in orbit around the star.[19][20]

Light curves for a flare on FI Virginis, seen in ultraviolet, blue and visual band light, adapted from Lee and Hoxie (1972),[21]

In 1972, a flare was detected from Ross 128. It was observed to increase in brightness by about half a magnitude in the ultraviolet U band, returning to normal brightness in less than an hour. At optical wavelengths, the brightness changes were almost undetectable.[21] It was classified as a flare star and given the variable star designation FI Virginis.[22] Because of the low rate of flare activity, it is thought to be a magnetically evolved star. That is, there is some evidence that the magnetic braking of the star's stellar wind has lowered the frequency of flares, but not the net yield.[23]

Brightness variations thought to be due to rotation of the star and magnetic cycles similar to the sunspot cycle have also been detected. These cause changes of just a few thousandths of a magnitude. The rotation period is found to be 165.1 days, and the magnetic cycle length 4.1 years.[24]

Ross 128 is orbiting through the galaxy with an eccentricity of 0.122, causing its distance from the Galactic Center to range between 26.8–34.2 kly (8.2–10.5 kpc).[25] This orbit will bring the star closer to the Solar System in the future. The nearest approach will occur in approximately 71,000 years, when it will come within 6.233 ± 0.085 ly (1.911 ± 0.026 pc).[9]

Planetary system

Main article: Ross 128 b
The Ross 128 planetary system[13]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b ≥1.40±0.13 M🜨 0.049640±0.000004 9.8556+0.0012
−0.0011 		0.21+0.09
−0.10 		— ~1.6+1.1
−0.65[26] R🜨

Ross 128 b was discovered in July 2017 by the HARPS instrument at the La Silla Observatory in Chile, by measuring changes in radial velocity of the host star. Its existence was confirmed on 15 November 2017. It is the second-closest known Earth-size exoplanet, after Proxima b.[27] Ross 128 b has a minimum mass 1.4 times that of Earth; a 2019 study predicts a true mass about 1.8 times Earth and a radius about 1.6 times that of the Earth, with large margins of error.[26] It orbits 20 times closer to its star than Earth orbits the Sun, intercepting only about 1.38 times more solar radiation than Earth,[28][29] increasing the chance of retaining an atmosphere over a geological timescale. Ross 128 b is a closely orbiting planet, with a year (orbital period) lasting about 9.9 days.[30][31] At that close distance from its host star, the planet is most likely tidally locked, meaning that one side of the planet would have eternal daylight and the other would be in darkness.[32][33] Near-infrared high-resolution spectra from APOGEE have demonstrated that Ross 128 has near solar metallicity; Ross 128 b therefore most likely contains rock and iron. Furthermore, recent models generated with these data support the conclusion that Ross 128 b is a "temperate exoplanet in the inner edge of the habitable zone."[34]

A 2024 study of the radial velocity data found an eccentricity of about 0.21 for Ross 128 b, higher than previous estimates and similar to that of Mercury. Given the planet's orbit near the inner edge of the habitable zone, such a high eccentricity would significantly decrease its potential for habitability. This study also searched for additional planets in the system, and did not find any.[13]

Radio signals

In the spring of 2017, Arecibo astronomers detected strange radio signals thought to originate from Ross 128 that were unlike any they had seen before.[35] SETI's Allen Telescope Array was used for follow-up observations and was unable to detect the signal but did detect man made interference, making it seem clear that the Arecibo detections were due to transmissions from Earth satellites in geosynchronous orbit. Ross 128 has a declination (a coordinate which can be likened to latitude) of close to 0 degrees, which places it in the thick of a phalanx of these satellites. Therefore, it can be concluded that the signal was a result of man-made interference.[36]

See also

References

  1. ^ "Closest Temperate World Orbiting Quiet Star Discovered – ESO's HARPS instrument finds Earth-mass exoplanet around Ross 128". www.eso.org. Retrieved 15 November 2017.
  2. ^ a b c d 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.
  3. ^ a b c d The One Hundred Nearest Star Systems, Research Consortium on Nearby Stars, 2012-01-01, retrieved 2017-11-15
  4. ^ a b c Gautier, Thomas N. III; et al. (2004), "Far Infrared Properties of M Dwarfs", Bulletin of the American Astronomical Society, 36: 1431, Bibcode:2004AAS...205.5503G
  5. ^ Rufener, F. (October 1976), "Second catalogue of stars measured in the Geneva Observatory photometric system", Astronomy & Astrophysics Supplement Series, 26: 275–351, Bibcode:1976A&AS...26..275R
  6. ^ Warren, W. H. Jr. (1978), "Photoelectric Photometric Catalogue of Homogeneous Means in the UBV System", Observatory, Geneva
  7. ^ Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007–2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  8. ^ Gontcharov, G. A. (2006), Pulkovo Compilation of Radial Velocities for 35493 Hipparcos Stars, retrieved 2010-04-18
  9. ^ a b García-Sánchez, J.; et al. (2001), "Stellar encounters with the solar system", Astronomy and Astrophysics, 379 (2): 634–659, Bibcode:2001A&A...379..634G, doi:10.1051/0004-6361:20011330
  10. ^ a b c d e f g Pineda, J. Sebastian; Youngblood, Allison; France, Kevin (September 2021). "The M-dwarf Ultraviolet Spectroscopic Sample. I. Determining Stellar Parameters for Field Stars". The Astrophysical Journal. 918 (1): 23. arXiv:2106.07656. Bibcode:2021ApJ...918...40P. doi:10.3847/1538-4357/ac0aea. S2CID 235435757. 40.
  11. ^ Rodonò, Marcello, "The Atmospheres of M Dwarfs: Observations", The M-Type Stars, Washington: NASA, pp. 409–453
  12. ^ Mann, Andrew W.; et al. (May 2015). "How to Constrain Your M Dwarf: Measuring Effective Temperature, Bolometric Luminosity, Mass, and Radius". The Astrophysical Journal. 804 (1): 38. arXiv:1501.01635. Bibcode:2015ApJ...804...64M. doi:10.1088/0004-637X/804/1/64. S2CID 19269312. Vizier catalogue entry
  13. ^ a b c Liebing, F.; Jeffers, S. V.; et al. (September 2024). "RedDots: Limits on habitable and undetected planets orbiting nearby stars GJ 832, GJ 674, and Ross 128". Astronomy & Astrophysics. 690: A234. arXiv:2409.01173. doi:10.1051/0004-6361/202347902.
  14. ^ 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. arXiv:1712.04490. Bibcode:2018MNRAS.475.1960F. doi:10.1093/mnras/stx3246.
  15. ^ McIntyre, S. R. N. (2022). "Tidally driven tectonic activity as a parameter in exoplanet habitability". Astronomy and Astrophysics. 662: A15. arXiv:2204.03501. Bibcode:2022A&A...662A..15M. doi:10.1051/0004-6361/202141112. S2CID 248005961.
  16. ^ "Ross 128". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 6 September 2024.
  17. ^ Ross, Frank E. (1926), "New proper-motion stars, (second list)", Astronomical Journal, 36 (856): 124–128, Bibcode:1926AJ.....36..124R, doi:10.1086/104699
  18. ^ Sánchez, F. (1990), Vazquez, M. (ed.), New windows to the universe, vol. 2, Cambridge University Press, p. 313, ISBN 0-521-38429-X
  19. ^ Jura, M.; et al. (September 2004), "Mid-Infrared Spectra of Dust Debris around Main-Sequence Stars", The Astrophysical Journal Supplement Series, 154 (1): 453–457, arXiv:astro-ph/0405632, Bibcode:2004ApJS..154..453J, doi:10.1086/422975, S2CID 396660
  20. ^ Gautier, Thomas N. III; et al. (September 2007), "Far-Infrared Properties of M Dwarfs", The Astrophysical Journal, 667 (1): 527–536, arXiv:0707.0464, Bibcode:2007ApJ...667..527G, doi:10.1086/520667, S2CID 15732144
  21. ^ a b Lee, T. A; Hoxie, D. T (1972). "The Observation of a Stellar Flare in the dM5 Star Ross 128". Information Bulletin on Variable Stars. 707: 1. Bibcode:1972IBVS..707....1L.
  22. ^ Kukarkin, B. V; Kholopov, P. N; Kukarkina, N. P; Perova, N. B (1975). "60th Name-List of Variable Stars". Information Bulletin on Variable Stars. 961: 1. Bibcode:1975IBVS..961....1K.
  23. ^ Skumanich, Andrew (1986-10-15), "Some evidence on the evolution of the flare mechanism in dwarf stars", Astrophysical Journal, Part 1, 309: 858–863, Bibcode:1986ApJ...309..858S, doi:10.1086/164654
  24. ^ Stelzer, B; Damasso, M; Scholz, A; Matt, S. P (2016). "A path towards understanding the rotation-activity relation of M dwarfs with K2 mission, X-ray and UV data". Monthly Notices of the Royal Astronomical Society. 463 (2): 1844. arXiv:1607.03049. Bibcode:2016MNRAS.463.1844S. doi:10.1093/mnras/stw1936. S2CID 55906368.
  25. ^ Allen, C.; Herrera, M. A. (1998), "The galactic orbits of nearby UV Ceti stars", Revista Mexicana de Astronomía y Astrofísica, 34: 37–46, Bibcode:1998RMxAA..34...37A
  26. ^ a b Tasker, Elizabeth J.; Laneuville, Matthieu; Guttenberg, Nicholas (7 January 2020). "Estimating Planetary Mass with Deep Learning". The Astronomical Journal. 159 (2): 41. arXiv:1911.11035. Bibcode:2020AJ....159...41T. doi:10.3847/1538-3881/ab5b9e. ISSN 1538-3881. S2CID 208267900.
  27. ^ Koren, Marina (15 November 2017). "An Earth-Sized Exoplanet in Our Cosmic Neighborhood". The Atlantic. The Atlantic Monthly Group. Retrieved 15 November 2017.
  28. ^ Bonfils, Xavier (2017). "A temperate exo-Earth around a quiet M dwarf at 3.4 parsecs". Astronomy and Astrophysics. 613: A25. arXiv:1711.06177. Bibcode:2018A&A...613A..25B. doi:10.1051/0004-6361/201731973. S2CID 37148632.
  29. ^ Nearby planet is 'excellent' target in search for life. Paul Rincon, BBC News. 15 November 2017.
  30. ^ Bonfils, Xavier (2017). "A temperate exo-Earth around a quiet M dwarf at 3.4 parsecs". Astronomy and Astrophysics. 613: A25. arXiv:1711.06177. Bibcode:2018A&A...613A..25B. doi:10.1051/0004-6361/201731973. S2CID 37148632.
  31. ^ A potentially habitable planet has been discovered just 11 light-years away. John Wenz, Astronomy Magazine. 15 November 2017.
  32. ^ Nearby Earth-sized Alien World Orbits 'Quiet' Star, Boosting Habitable Potential. Ian O'Neill, How Stuff Works. 15 November 2017. Quote: "Tidal lock[ing] is expected for Ross 128 b," says Nicola Astudillo-Defru, who works at the Geneva Observatory, University of Geneva in Switzerland, and is co-author of the study.
  33. ^ Ross 128. Sol Station. November 2017.
  34. ^ Souto, Diogo; Unterborn, Cayman T.; Smith, Verne V.; Cunha, Katia; Teske, Johanna; Covey, Kevin; Bárbara Rojas-Ayala; García-Hernández, D. A.; Stassun, Keivan (2018). "Stellar and Planetary Characterization of the Ross 128 Exoplanetary System from APOGEE Spectra". The Astrophysical Journal Letters. 860 (1): L15. arXiv:1805.11633. Bibcode:2018ApJ...860L..15S. doi:10.3847/2041-8213/aac896. hdl:10150/628573. ISSN 2041-8205. S2CID 89612773.
  35. ^ Koren, Marina (July 17, 2017). "The Strange Radio Signals Coming From a Nearby Star – Astronomers have detected a mystery transmission at a frequency they haven't observed before". The Atlantic. Retrieved July 17, 2017.
  36. ^ Shostak, Seth. "Signals from A Nearby Star System?". seti.org. Retrieved 17 September 2017.
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