Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Cetus |
Right ascension | 02h 33m 49.026s [1] |
Declination | –19° 36′ 42.500″ [1] |
Apparent magnitude (V) | 8.58 [2] |
Characteristics | |
Evolutionary stage | Main sequence |
Spectral type | G5V [2] |
Astrometry | |
Radial velocity (Rv) | 14.45±0.14 [3] km/s |
Proper motion (μ) | RA: +223.559 mas/yr [3] Dec.: +35.513 mas/yr [3] |
Parallax (π) | 18.6292 ± 0.0224 mas [3] |
Distance | 175.1 ± 0.2 ly (53.68 ± 0.06 pc) |
Absolute magnitude (MV) | 4.83 [4] |
Details | |
Mass | 0.991±0.003 [5] M☉ |
Radius | 0.974±0.001 [3] R☉ |
Luminosity | 1.0+0.13 −0.12 [6] L☉ |
Surface gravity (log g) | 4.47±0.008 [5] cgs |
Temperature | 5773±2 [5] K |
Metallicity [Fe/H] | −0.057±0.003 [5] dex |
Rotational velocity (v sin i) | 0.99 ± 0.15 km/s |
Age | 3.87±0.39 [5] Gyr |
Other designations | |
Database references | |
SIMBAD | data |
HIP 11915 is a G-type main-sequence star located about 170 light-years from Earth in the constellation Cetus. It is best known for its characteristics, which are very similar to those of the Sun, including the mass, radius, temperature, metallicity and age, which means that it is almost a solar twin, being just 500 million years younger than the Sun and with a lower metallicity. [lower-alpha 1] It is also known for its planetary companion, HIP 11915 b, which has a mass and orbital distance very similar to that of Jupiter, but probably with a slightly higher orbital eccentricity.
This star is entry number 11915 in the Hipparcos Catalogue. The star is located at 02:33:49.02495 right ascension, −19° 36' 42.5032" dec. [1] [9] Too faint to be seen with the unaided eye, the star can be spotted with good binoculars. [9]
HIP 11915 is a G-type main sequence star that is just about the same mass of and likely 101% the radius of the Sun. It has a temperature of 5760 K and is 4.16 billion years old, [2] [10] nearly 500 million years younger than the Sun, which is about 4.6 billion years old [11] and has a temperature of 5778 K. [12]
The star is slightly poor in metals, with a metallicity ([Fe/H]) of about −0.059, or about 87% of the amount of iron and other heavier metals found in the Sun. [10] Given the similar properties of the Sun, HIP 11915's luminosity is likely close to the same as the Sun (give or take about 10% in uncertainty).
Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
b | 0.99 ± 0.06 MJ | 4.8 ± .01 | 3830.0 ± 150 | 0.1 ± 0.07 | — | ~1 RJ |
The system contains a gas giant, HIP 11915 b, with a mass and orbit very similar to that of Jupiter, located at approximately the same distance from its star. The discovery of HIP 11915 b is significant, because it is the first, and to date only, distant planetary system found that may be somewhat like the Solar System. [13] The radial velocity data also indicates that there is no large gas giant in this system with an orbital period of less than 1000 days. This means that there could be one or more terrestrial planets in the inner parts of the system, and the possibility of a habitable Earth-like planet.
This new discovery was made at the La Silla Observatory in Chile, using the High Accuracy Radial Velocity Planet Searcher instrument mounted on the European Southern Observatory's 3.6-meter telescope. [14] [15]
According to Jorge Meléndez, who led the University of São Paulo, Brazil team that discovered HIP 11915 b, "the quest for an Earth 2.0, and for a complete Solar System 2.0, is one of the most exciting endeavors in astronomy". [16]
This chart compares the properties of the Sun to HIP 11915.
Identifier | J2000 Coordinates | Distance (ly) | Stellar Class | Mass (M☉) | Radius (R☉) | Temperature (K) | Metallicity (dex) | Age (Gyr) | Notes | |
---|---|---|---|---|---|---|---|---|---|---|
Right ascension | Declination | |||||||||
Sun | — | — | 0.00 | G2V | 1 | 1 | 5,778 | +0.00 | 4.6 | [8] |
HIP 11915 [17] | 02h 33m 49.02s | −19° 36′ 42.5″ | 190 | G5V | 0.99 | 1.01 | 5,760 | −0.059 | 4.1 | [18] |
HD 169830 is a star in the southern constellation of Sagittarius. It has a yellow-white hue and is dimly visible to the naked eye with an apparent visual magnitude of +5.90. The star is located at a distance of 120 light years from the Sun based on parallax. It is drifting closer with a radial velocity of −17.3 km/s, and is predicted to come as close as 20.7 ly (6.4 pc) in 2.08 million years. HD 169830 is known to be orbited by two large Jupiter-like exoplanets.
HD 330075 is a star in the southern constellation of Norma. It has a yellow hue and an apparent visual magnitude of 9.36, which makes it too faint to be seen with the naked eye – it is visible only with telescope or powerful binoculars. Parallax measurements provide a distance estimate of 148 light years from the Sun, and it is drifting further away with a radial velocity of 62 km/s. The star is estimated to have come as close as 111.5 light-years some 409 million years ago.
Solar-type stars, solar analogs, and solar twins are stars that are particularly similar to the Sun. The stellar classification is a hierarchy with solar twin being most like the Sun followed by solar analog and then solar-type. Observations of these stars are important for understanding better the properties of the Sun in relation to other stars and the habitability of planets.
HD 1237 is a binary star system approximately 57 light-years away in the constellation of Hydrus.
HD 2039 is a yellow dwarf or yellow subgiant star in the constellation Phoenix. The star is not visible to the naked eye, and lies 280 light years away from the Sun. HD 2039 is a relatively stable star, and an exoplanet at least three times the mass of the planet Jupiter has been discovered in its orbit; this exoplanet, known as HD 2039 b, was the 100th exoplanet to be discovered.
HD 222582 is a multiple star system in the equatorial constellation of Aquarius. It is invisible to the naked eye with an apparent visual magnitude of 7.7, but can be viewed with binoculars or a small telescope. The system is located at a distance of 137 light years from the Sun based on parallax, and it is drifting further away with a radial velocity of +12 km/s. It is located close enough to the ecliptic that it is subject to lunar occultations.
HD 73256 is a variable star in the southern constellation of Pyxis. It has the variable star designation CS Pyxidis. With a baseline apparent visual magnitude of 8.08, it requires binoculars or a small telescope to view. The star is located at a distance of 120 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +30 km/s.
HD 141937 is a star in the southern zodiac constellation of Libra, positioned a couple of degrees to the north of Lambda Librae. It is a yellow-hued star with an apparent visual magnitude of 7.25, which means it is too faint to be seen with the naked eye. This object is located at a distance of 108.9 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −2.2 km/s. It has an absolute magnitude of 4.71.
HD 142415 is a single star in the southern constellation of Norma, positioned next to the southern constellation border with Triangulum Australe and less than a degree to the west of NGC 6025. With an apparent visual magnitude of 7.33, it is too faint to be visible to the naked eye. The distance to this star is 116 light years from the Sun based on parallax, but it is drifting closer with a radial velocity of −12 km/s. It is a candidate member of the NGC 1901 open cluster of stars.
HD 190228 is a star with an orbiting substellar companion in the northern constellation of Vulpecula. Its apparent magnitude is 7.30 – too faint to be seen with the naked eye – and the absolute magnitude is 3.34. Based on parallax measurements, it is located at a distance of 205 light-years from the Sun. The system is drifting closer with a radial velocity of −50 km/s.
36 Ursae Majoris is a double star in the northern constellation of Ursa Major. With an apparent visual magnitude of 4.8, it can be seen with the naked eye in suitable dark skies. Based upon parallax measurements, this binary lies at a distance of 42 light-years from Earth.
HD 131664 is an 8th magnitude star in the southern constellation of Apus with an orbiting brown dwarf or stellar companion. Parallax measurements by the Gaia space observatory provide an estimated distance of 172.5 light years from the Earth. The system is moving further away with a baseline heliocentric radial velocity of +35 km/s.
HIP 56948 is a solar twin star of type G5V. It is one of the most Sun-like stars yet known in terms of size, mass, temperature, and chemical makeup. The Sun is about 4.6 billion years old, and HIP 56948 is believed to be about 7.1 billion years old. Both stars are between a third and a halfway through their life on the main sequence.
HD 6718 is a solar twin star in the equatorial constellation of Cetus. It has a yellow hue but is too faint to be viewed with the naked eye, having an apparent visual magnitude of 8.45. The distance to this object, as determined from parallax measurements, is 168 light years. It is drifting away from the Sun with a radial velocity of +35 km/s.
HIP 12961 is a star with an exoplanetary companion in the equatorial constellation of Eridanus. It is too faint to be visible to the naked eye, with an apparent visual magnitude of 10.24. The distance to this system can be estimated from its parallax measurements, which yield a separation of 76.4 light-years from the Sun. It is receding with a radial velocity of +33 km/s and has a high proper motion, traversing the celestial sphere at an angular rate of 0.300″ yr−1.
HIP 70849 is a star with two non-stellar companions in the southern constellation Lupus. It is a 10th magnitude star, making it too faint to be visible to the naked eye. The system is located at a distance of 78.7 light-years from the Sun based on parallax measurements.
YBP 1194 is a G-type main-sequence star, class G5V, in the open cluster Messier 67, about 2,890 light-years from the Sun in the constellation Cancer. It is a solar twin, having the near exact same temperature and mass as the Sun. YBP 1194 has a slightly higher metallicity than the Sun, and may be slightly younger at an age of 3.5-4.8 billion years. In January 2014, this star was announced to have an exoplanet. It is packed in a small cluster, Messier 67, with a radius of 10 light-years, with over 500 other stars. For comparison, the Sun has 9 star systems within 10 light-years and 94 star systems within 20 light-years.
HIP 11915 b is an exoplanet orbiting the solar twin star HIP 11915 about 190 light-years (57 parsecs, or nearly 1.798×1015 km) from Earth in the constellation Cetus. It is notable as the first exoplanet to be discovered with an orbit and mass similar to that of Jupiter (essentially, a "Jupiter analog"), suggesting that its system may be similar to that of the Solar System. It orbits its star at a distance of approximately 4.8 AU. The exoplanet was found by using the radial velocity method, where periodic Doppler shifts of spectral lines of the host star suggest an orbiting object.
HD 164595 is a wide binary star system in the northern constellation of Hercules. The primary component of this pair hosts an orbiting exoplanet. The system is located at a distance of 92 light years from the Sun based on parallax measurements, and is drifting further away with a radial velocity of 2.0 km/s. Although it has an absolute magnitude of +4.81, at that distance it is too faint to be viewed with the naked eye, having an apparent visual magnitude of 7.07. The brighter star can be found with binoculars or a small telescope less than a degree to the east-northeast of Xi Herculis. HD 164595 has a relatively large proper motion, traversing the celestial sphere at an angular rate of 0.222″ yr−1.
HD 168009 is a star in the northern constellation of Lyra. It has an apparent visual magnitude of 6.3, placing it just above to below the normal limit of stars visible to the naked eye under good viewing conditions of 6-6.5. An annual parallax shift of 42.93 mas provides a distance estimate of 76 light years. It is moving closer to the Sun with a heliocentric radial velocity of −65 km/s. In about 328,000 years from now, the star will make its closest approach at a distance of around 17 ly (5.1 pc).