HD 4628
Encyclopedia
HD 4628 is a main sequence
dwarf star
star
in the constellation
Pisces
. It has a spectral classification of K2, giving it an orange-red hue and a slightly smaller mass and girth than our Sun
. It lies at a distance of approximately 24 light years from us and has a relatively high proper motion
. The apparent magnitude
is just sufficient for this star to be viewed with the unaided eye. The star appears to be slightly older than our Sun—approximately 5.4 billion years old.
No definitive companion has yet been found in orbit around this star. In 1958 it was thought to have stellar companion that was also a flare star
, but this was subsequently disproved. A Jupiter-like planetary companion has been inferred but not confirmed so far.
-mass (and Jupiter-sized) planetary companion in Jovian orbital zone could explain a periodicity of roughly 10 years detected in radial velocity observations. The planetary candidate has not been confirmed so far.
Main sequence
The main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell...
dwarf star
Dwarf star
The term dwarf star refers to a variety of distinct classes of stars.* Dwarf star alone generally refers to any main sequence star, a star of luminosity class V.** Red dwarfs are low-mass main sequence stars....
star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on 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....
Pisces
Pisces (constellation)
Pisces is a constellation of the zodiac. Its name is the Latin plural for fish, and its symbol is . It lies between Aquarius to the west and Aries to the east...
. It has a spectral classification of K2, giving it an orange-red hue and a slightly smaller mass and girth than our Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
. It lies at a distance of approximately 24 light years from us and has a relatively high proper motion
Proper motion
The proper motion of a star is its angular change in position over time as seen from the center of mass of the solar system. It is measured in seconds of arc per year, arcsec/yr, where 3600 arcseconds equal one degree. This contrasts with radial velocity, which is the time rate of change in...
. The 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...
is just sufficient for this star to be viewed with the unaided eye. The star appears to be slightly older than our Sun—approximately 5.4 billion years old.
No definitive companion has yet been found in orbit around this star. In 1958 it was thought to have stellar companion that was also 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...
, but this was subsequently disproved. A Jupiter-like planetary companion has been inferred but not confirmed so far.
A planetary system?
According to Cumming et al. (1999) the presence of a JupiterJupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
-mass (and Jupiter-sized) planetary companion in Jovian orbital zone could explain a periodicity of roughly 10 years detected in radial velocity observations. The planetary candidate has not been confirmed so far.