Ross 248
Encyclopedia
Ross 248 is a red dwarf
star located approximately 10.3 light years (3.2 pc
) from Earth in the constellation
Andromeda
. This star was first catalogued by Frank Elmore Ross
in 1926 with his second list of proper motion stars.
This star has about 12% of the Sun's mass
and 16% of the Sun's radius, but only 0.2% of the Sun's luminosity. Despite its proximity to the Earth, it is too dim to be seen with the naked eye. This is a flare star
that occasionally increases in luminosity. With high probability there also appears to be a long-term variability with a period of 4.2 years. This variability ranged in visual magnitude from 12.23 to 12.34. In 1950, this became the first star to have a small variation in magnitude attributed to spots on the photosphere
.
Long term observations of this star by the Sproul Observatory
show no astrometric perturbations by an unseen companion. The proper motion of this star was examined for a brown dwarf
or stellar companion orbiting at a wide separation (between 100–1400 AU
) but none was found. A search for a faint companion using the Hubble Space Telescope
Wide Field Planetary Camera revealed nothing, nor did a search with near infrared speckle interferometry. However, none of these searches rule out a companion that is smaller than the detection minima.
The space velocity components of this star are U = –32.9 ± 0.7, V = –74.3 ± 1.3 and W = 0.0 ± 1.4 km/s. The trajectory of Ross 248 will bring it closer to the Solar System in the future. In 1993 Matthews suggested that in about 33,000 years Ross 248 would be the closest star to the Sun, approaching within a minimum distance of 3.024 ly in 36,000 years. However, it will recede thereafter and will again be further from the Sun than Proxima Centauri
42,000 years from now.
The spacecraft
Voyager 2
is traveling on a path headed roughly in the direction of Ross 248, and is expected to come within 1.76 ly of the star in 40,176 years. A spacecraft that escaped the Solar System with a velocity of 25.4 km/s would reach this star 37,000 years from now when the star is just past its nearest approach. By comparison, the Voyager 1
has an escape velocity of 16.6 km/s.
Red dwarf
According to the Hertzsprung-Russell diagram, a red dwarf star is a small and relatively cool star, of the main sequence, either late K or M spectral type....
star located approximately 10.3 light years (3.2 pc
Parsec
The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres ....
) from Earth in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Andromeda
Andromeda (constellation)
Andromeda is a constellation in the northern sky. It is named after Andromeda, the princess in the Greek legend of Perseus who was chained to a rock to be eaten by the sea monster Cetus...
. This star was first catalogued by Frank Elmore Ross
Frank Elmore Ross
Frank Elmore Ross was an American astronomer and physicist. He was born in San Francisco, California and died in Altadena, California. In 1901 he received his doctorate from the University of California. In 1905 he became director of the International Latitude Observatory station at Gaithersburg,...
in 1926 with his second list of proper motion stars.
This star has about 12% of the Sun's mass
Solar mass
The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...
and 16% of the Sun's radius, but only 0.2% of the Sun's luminosity. Despite its proximity to the Earth, it is too dim to be seen with the naked eye. This is a flare star
Flare star
A flare star is a variable star that can undergo unpredictable dramatic increases in brightness for a few minutes. It is believed that the flares on flare stars are analogous to solar flares in that they are due to magnetic reconnection in the atmospheres of the stars. The brightness increase is...
that occasionally increases in luminosity. With high probability there also appears to be a long-term variability with a period of 4.2 years. This variability ranged in visual magnitude from 12.23 to 12.34. In 1950, this became the first star to have a small variation in magnitude attributed to spots on the photosphere
Photosphere
The photosphere of an astronomical object is the region from which externally received light originates. The term itself is derived from Ancient Greek roots, φῶς, φωτός/phos, photos meaning "light" and σφαῖρα/sphaira meaning "sphere", in reference to the fact that it is a spheric surface perceived...
.
Long term observations of this star by the Sproul Observatory
Sproul Observatory
Sproul Observatory is an astronomical observatory owned and operated by Swarthmore College. It is located in Swarthmore, Pennsylvania, United States, and is named after William Cameron Sproul, the 27th Governor of Pennsylvania, who graduated from Swarthmore in 1891.-Tours:An open house is offered...
show no astrometric perturbations by an unseen companion. The proper motion of this star was examined for a brown dwarf
Brown dwarf
Brown dwarfs are sub-stellar objects which are too low in mass to sustain hydrogen-1 fusion reactions in their cores, which is characteristic of stars on the main sequence. Brown dwarfs have fully convective surfaces and interiors, with no chemical differentiation by depth...
or stellar companion orbiting at a wide separation (between 100–1400 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
) but none was found. A search for a faint companion using the Hubble Space Telescope
Hubble Space Telescope
The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...
Wide Field Planetary Camera revealed nothing, nor did a search with near infrared speckle interferometry. However, none of these searches rule out a companion that is smaller than the detection minima.
The space velocity components of this star are U = –32.9 ± 0.7, V = –74.3 ± 1.3 and W = 0.0 ± 1.4 km/s. The trajectory of Ross 248 will bring it closer to the Solar System in the future. In 1993 Matthews suggested that in about 33,000 years Ross 248 would be the closest star to the Sun, approaching within a minimum distance of 3.024 ly in 36,000 years. However, it will recede thereafter and will again be further from the Sun than Proxima Centauri
Proxima Centauri
Proxima Centauri is a red dwarf star about 4.2 light-years distant in the constellation of Centaurus. It was discovered in 1915 by Robert Innes, the Director of the Union Observatory in South Africa, and is the nearest known star to the Sun, although it is too faint to be seen with the naked eye...
42,000 years from now.
The spacecraft
Spacecraft
A spacecraft or spaceship is a craft or machine designed for spaceflight. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, planetary exploration and transportation of humans and cargo....
Voyager 2
Voyager 2
The Voyager 2 spacecraft is a 722-kilogram space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space...
is traveling on a path headed roughly in the direction of Ross 248, and is expected to come within 1.76 ly of the star in 40,176 years. A spacecraft that escaped the Solar System with a velocity of 25.4 km/s would reach this star 37,000 years from now when the star is just past its nearest approach. By comparison, the Voyager 1
Voyager 1
The Voyager 1 spacecraft is a 722-kilogram space probe launched by NASA in 1977, to study the outer Solar System and eventually interstellar space. Operating for as of today , the spacecraft receives routine commands and transmits data back to the Deep Space Network. At a distance of as of...
has an escape velocity of 16.6 km/s.
Field star
| NAME | Right ascension Right ascension Right ascension is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. The other coordinate is the declination.-Explanation:... |
Declination Declination In astronomy, declination is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. Declination in astronomy is comparable to geographic latitude, but projected onto the celestial sphere. Declination is measured in degrees north and... |
Apparent magnitude Apparent magnitude The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere... (V) |
Spectral type | Database references |
|---|---|---|---|---|---|
| PLX 5735 | 23h 41m 54s | +44° 14' 00 | 12.6 | A5 | Simbad |