Template:Short description Template:Starbox begin Template:Starbox image Template:Starbox observe Template:Starbox character Template:Starbox astrometry Template:Starbox detail Template:Starbox catalog Template:Starbox reference Template:Starbox end 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,<ref name="RECONS"/> which is too faint to be seen with the unaided eye. Based upon parallax measurements, the distance of this star from Earth is Template:Convert, making it the twelfth closest stellar system to the Solar System. It was first cataloged in 1926 by American astronomer Frank Elmore Ross.<ref name=aj36_856_124/>
PropertiesEdit
This low-mass star has a stellar classification of M4 V,<ref name="baas36"/> which places it among the category of stars known as red dwarfs. It has about 18%<ref name="Pineda2021"/> of the mass of the Sun and 20%<ref name="Pineda2021"/> of the Sun's radius, but generates energy so slowly that it has only 0.033% of the Sun's visible luminosity;<ref name="RECONS"/> 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.<ref name="Pineda2021"/> This energy is being radiated from the star's outer atmosphere at an effective temperature of 3,180 K.<ref name="baas36"/> 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.<ref name=sanchez1990/> 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.<ref name=apjss154_1_453/><ref name=apj667_1_527/>
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.<ref name=lee/> It was classified as a flare star and given the variable star designation FI Virginis.<ref name=ibvs/> 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.<ref name=apj1_309_858/>
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.<ref name=sm/>
Ross 128 is orbiting through the galaxy with an eccentricity of 0.122, causing its distance from the Galactic Center to range between Template:Convert.<ref name=rmaa34_37/> 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 Template:Convert.<ref name=aaa379 />
Planetary systemEdit
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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.<ref name="Atlantic">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> 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.<ref name="TaskerLaneuville2020"/> It orbits 20 times closer to its star than Earth orbits the Sun, intercepting only about 1.38 times more solar radiation than Earth,<ref name="4-planet"/><ref>Nearby planet is 'excellent' target in search for life. Paul Rincon, BBC News. 15 November 2017.</ref> 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.<ref name="1-planet">Template:Cite journal</ref><ref name='AstronomyMag'>A potentially habitable planet has been discovered just 11 light-years away Template:Webarchive. John Wenz, Astronomy Magazine. 15 November 2017.</ref> 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.<ref name=Locked>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.</ref><ref>Ross 128. Sol Station. November 2017.</ref> 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."<ref>Template:Cite journal</ref>
Template:OrbitboxPlanet begin Template:OrbitboxPlanet Template:Orbitbox end
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.<ref name="Liebing2024"/>
Radio signalsEdit
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.<ref name="TA-20170717"/> 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.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
See alsoEdit
- List of nearest stars and brown dwarfs
- PSR B1919+21 – pulsar mistaken for an alien radio signal (LGM-1)