Ross 128 is a red dwarf star located around 11.03 light years away from Earth in the constellation of Virgo, making it the 12th closest star system to the Solar System. The apparent magnitude of Ross 128 is 11.13, which is too faint to be seen with the naked eye. It was first cataloged in 1926 by American astronomer Frank Elmore Ross.
Characteristics[]
Ross 128 has a stellar classification of M4 V, which places it among the category of stars known as "red dwarfs". It has 15% of the Sun's mass and 21% of the Sun's radius, but generates energy so slowly that it has only 0.036% of the Sun's visible luminosity; however, most of the energy being radiated by the star is in the infrared band, with the bolometric luminosity being equal to 0.35% of solar. The star has an effect temperature of 3,192 K, which 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.
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
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. It was classified as a flare star and given the variable star designation FI Virginis. 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.
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.
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 kilolightyears (8.2-10.5 kiloparsecs). 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).
Radio signal[]
On May 12, 2017, researchers observing Ross 128 picked up a mysterious radio signals using the Arecibo Observatory. Abel Méndez, an astrobiologist at the University of Puerto Rico at Arecibo, said the star was observed for ten minutes, during which time the wide-band radio signal was "almost periodic", and decreased in frequency. On July 16, 2017, the strange signal, at a low frequency never heretofore observed from a red dwarf, was reported on Twitter by Méndez to have been "confirmed". However, no such signals were detected in further follow-up studies by Arecibo, nor by the Green Bank Telescope in West Virginia and the Allen Telescope Array (ATA) in northern California, as well, suggesting the likelihood that the signals detected earlier were radio frequency interference from an artificial satellite orbiting the Earth.
Planetary system[]
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 November 15, 2017. It is the second-closest known Earth-size exoplanet, after Proxima Centauri b. It is calculated that Ross 128 b has a minimum mass of 1.35 times the Earth, and orbits 20 times closer to its star than Earth orbits the Sun, intercepting only about 1.38 times more solar radiation than Earth, increasing the chance of retaining an atmosphere over a geological timescale. Ross 128 b is a closely orbiting planet, with a year (rotation period) lasting about 9.9 days. At that close distance from its host star, the planet is most likely tidally locked, meaning that one side of the planet would be in permanent daylight, while the other side would be in permanent darkness. As of 2017, Ross 128 b is the best candidate for a potentially habitable exoplanet, if it has an atmosphere and if it has the right chemical balance for life to thrive.
| Planet | Mass | Semimajor axis | Orbital period (days) | Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | >1.35 Earth mass | 0.0493 AU | 9.8596 days | 0.036 | N/A | N/A |