Ross 154 (V1216 Sgr) is a red dwarf star approximately 3.0 pc or 9.68 light years from the Sun. It is the nearest star in the southern constellation Sagittarius, and one of the closest to the Sun. Its nearest neighbor is Barnard's star, located 1.66 pc (5.41 ly) away.
This star was first catalogued by Frank Elmore Ross in 1925, and formed part of his fourth list of new variable stars. It was found to be a UV Ceti-type flare star, with a mean time between major flares of about two days. Typically, the star will increase by 3–4 magnitudes during a flare. However, at 11th magnitude, this star is much too faint to be viewed with the unaided eye and requires at least a 65 mm telescope aperture to be seen under ideal conditions.
Ross 154 has an estimated 17% of the Sun's mass and is only 24% of the Sun's radius. Based on the relatively high projected rotation, this is probably a young star with an estimated age of less than a billion years. The abundance of elements heavier than helium is about half that of the Sun. The strength of the star's magnetic field is an estimated 2.6±0.3 kG. This star is an X-ray source and it has been detected by several X-ray observatories. X-ray flare emission from Ross 154 has been observed by Chandra observatory.
The space velocity components of this star are U = –12.2, V = -1.0 and W = -7.2 km/s. It has not been identified as a member of a specific stellar moving group. It is orbiting through the Milky Way galaxy at a distance from the core that varies from 8.478–9.400 kpc and an orbital eccentricity of 0.052. Based on its low velocity relative to the Sun, this is believed to be a young disk (Population I) star. It is predicted that this star will make its closest approach to the Sun in 150,000 years, when it comes within 1.88 ± 0.08 pc (6.13 ly).
No low-mass companions have been discovered in orbit around this star.
Ross 154 in Space Opera:
- Frontier: Elite II? and Frontier: First Encounters?, computer games. The moon Merlin orbits a gas giant planet of Ross 154. Merlin is an ice world similar to Europa. Its primary export is fish, harvested from the liquid ocean that exists below the icy crust. Importing luxury goods from Sol and illegally exporting animal skins to Barnard's Star is a profitable enterprise. Ross 154 is the primary starting point of Frontier: Elite II?.
- Night’s Dawn Trilogy?, by Peter F. Hamilton?: Nyvan, a “terracompatible planet” orbiting Ross 154, was the second Human colony of more than 600 as of 2611, the trilogy’s fictional present. An important part of the 2nd volume plays in Tonala, one of Nyvan’s many countries.20
- In C.J. Cherryh's Alliance-Union future history, Ross 154 is the site of Glory Station, one of the stations on the "Great Circle" chain of space stations that terminates at Pell Station in the Tau Ceti system.