HIP 56948

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HIP 56948
Observation data
Epoch J2000       Equinox J2000
Constellation Draco
Right ascension 11h 40m 28.48381s [1]
Declination +69° 00′ 30.5995″ [1]
Apparent magnitude  (V)8.70
Characteristics
Spectral type G5V [2]
U−B color index 0.155
B−V color index 0.647 ± 0.014 [1]
Variable type none
Astrometry
Radial velocity (Rv)5.4 [3]  km/s
Proper motion (μ)RA: –126.96 [1]   mas/yr
Dec.: –2.13 [1]   mas/yr
Parallax (π)15.68 ± 0.67  mas [1]
Distance 208 ± 9  ly
(64 ± 3  pc)
Absolute magnitude  (MV)4.81
Details
Mass 1.02 ± 0.02 [4]   M☉
Radius 0.99  R☉
Luminosity 0.99 [5]   L☉
Surface gravity (log g)4.409 [5]   cgs
Temperature 5795 [5]   K
Metallicity [Fe/H]0.02 [5]   dex
Age ~7.1 [6]   Gyr
Other designations
HD 101364, BD+69 620, SAO 15590.
Database references
SIMBAD data
Exoplanet Archive data

HIP 56948 (also known as HD 101364) is a solar twin star of type G5V. [2] 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. [6] [7]

Contents

Cross-section of a solar-type star (NASA) Sun parts big.jpg
Cross-section of a solar-type star (NASA)

It is 208 light years away in the constellation of Draco, [8] lying about halfway between Polaris and Dubhe on the celestial sphere. [9] Astronomers have looked for planets in the system, so far without finding any. These observations suggest that the star does not have any hot Jupiters. [10]

Jorge Meléndez of the Australian National University and Iván Ramírez of the University of Texas analysed the star in 2007 using the 2.7 metre Harlan J. Smith telescope at McDonald Observatory. [11]

Most other solar analogs such as 18 Scorpii are unlike the Sun in that they have several times the lithium abundance. HIP 56948 is among the best candidates for a solar twin because of the known possible contenders, its lithium abundance most resembles that of the Sun. [5] [12] A 2009 high-dispersion spectroscopic study from the Astronomical Society of Japan confirms this. [5]

In the abstract to their paper, the star's discoverers say: [7]

For more than a decade, 18 Sco (HD 146233) has been considered the star that most closely resembles the Sun, even though significant differences such as its Li content, which is about 3 times solar, exist. Using high-resolution, high-S/N spectra obtained at McDonald Observatory, we show that the stars HIP 56948 and HIP 73815 are very similar to the Sun in both stellar parameters and chemical composition, including a low Li abundance, which was previously thought to be peculiar in the Sun. HIP 56948, in particular, has stellar parameters identical to solar within the observational uncertainties, being thus the best solar twin known to date. HIP 56948 is also similar to the Sun in its lack of hot Jupiters. Considering the age of this star (~1 ± 1 Gyr older than the Sun) [Notes 1] and its location and orbit around the Galaxy, if terrestrial planets exist around it, they may have had enough time to develop complex life, making it a prime target for SETI.

— Jorge Meléndez and Iván Ramírez, 8 October 2007

See also

Notes

  1. ↑ The star's age estimate has been revised several times in different studies, most recently (as of February 2020) to 7.1 Gyr. [6]

Related Research Articles

<span class="mw-page-title-main">16 Cygni</span> Multiple star in the constellation Cygnus

16 Cygni or 16 Cyg is a triple star system approximately 69 light-years away from Earth in the constellation of Cygnus. It consists of two Sun-like yellow dwarf stars, 16 Cygni A and 16 Cygni B, together with a red dwarf, 16 Cygni C. In 1996 an extrasolar planet was discovered in an eccentric orbit around 16 Cygni B.

<span class="mw-page-title-main">18 Scorpii</span> Star in the constellation Scorpius

18 Scorpii is a solitary star located at a distance of some 46.1 light-years from the Sun at the northern edge of the Scorpius constellation. It has an apparent visual magnitude of 5.5, which is bright enough to be seen with the naked eye outside of urban areas. The star is drifting further away with a radial velocity of +11.6.

<span class="mw-page-title-main">Solar analog</span> Star that is particularly similar to the Sun

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 98618 is a yellow-hued star in the northern circumpolar constellation of Ursa Major. It is invisible to the naked eye, having an apparent visual magnitude of just 7.65. Based on measurements, this star is located at a distance of 135 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +7.1 km/s. It is a likely member of the thin disk population and is orbiting the Milky Way at about the same distance from the Galactic Center as the Sun.

HR 1614 is a star in the constellation Eridanus. Based upon parallax measurements, it is about 28.8 light-years distant from the Earth. It is a main sequence star with a stellar classification of K3V. The chromosphere has an effective temperature of about 4,945 K, which gives this star the orange hue characteristic of K-type stars. It has about 84% of the Sun's mass and 78% of the Sun's radius.

HD 143436 also known as HIP 78399, is a G-type star in the constellation Serpens. The temperature, rotation, mass, and abundance of elements in this star are close to properties of the Sun, and for this reason it is a solar twin candidate. The only notable difference is an approximately six times higher abundance of lithium compared to the Sun and most likely a younger age of 3.8 Gyr. The space velocity components of this star are = km/s.

HD 44594 is a star in the southern constellation Puppis. It has an apparent visual magnitude of 6.64, so it can be seen with the naked eye from the southern hemisphere under good viewing conditions. Based upon parallax measurements, it is located at a distance of 85 light-years from the Earth, giving it an absolute magnitude of 4.56.

HD 27274, also known as Gliese 167, is a solitary, orange hued star located in the southern constellation Dorado. It has an apparent magnitude of 7.63, making it readily visible in binoculars, but not to the naked eye. Based on parallax measurements from the Gaia spacecraft, the star is known to be located 42.5 light-years away from the Solar System However, it is drifting closer with a heliocentric radial velocity of −23 km/s. At its current distance, HD 27274 is dimmed down by 0.05 magnitudes due to interstellar dust.

HD 129357 is a G-type star in the constellation Boötes that is located about 154 light years from the Sun. The measured properties of this star are very similar to those of the Sun, making it a candidate solar twin. However, it has a lower abundance of lithium than the Sun and appears over 3 billion years older, so it may instead be a solar analog. It was suggested by astronomer Olin Eggen that this star is a member of the Wolf 630 moving group of stars that share a common motion through space. The space velocity components of HD 129357 are (U, V, W) = (+21.3, −36.3, −32.0).

HD 79498 is a double star in the northern constellation of Cancer. The primary component of this pair has an orbiting exoplanet companion. This star is too faint to be viewed with the naked eye, having an apparent visual magnitude of 8.05. The system is located at a distance of 159 light years based on parallax measurements, and is drifting further away with a heliocentric radial velocity of 20 km/s. It has a relatively high proper motion, traversing the celestial sphere at an angular rate of 0.2″·yr−1.

HIP 100963 is a G-type star in the faint northern constellation of Vulpecula resembling the Sun. It has an apparent visual magnitude of approximately 7.1, making it generally too faint to be seen with the naked eye in most circumstances. The distance to this star, as determined using parallax measurements from the Gaia spacecraft, is around 92 light-years.

HD 133600, also known as HIP 73815, is a G-type star in the constellation of Virgo. It has an apparent visual magnitude of approximately 8.219m. It is similar to the Sun and has been called a near solar twin, as it is 1.5 billion years older than the Sun.

HD 162826 is a star in the constellation Hercules. It is about 110 light-years away from Earth. With an apparent magnitude of 6.55, the star can be found with binoculars or a low-power telescope by reference to nearby Vega in the constellation Lyra.

10 Canum Venaticorum is an ordinary star in the northern constellation of Canes Venatici. It has an apparent visual magnitude of 5.95, which, according to the Bortle scale, can be faintly seen with the naked eye from suburban locations. Based upon an annual parallax shift of 0.057 arcseconds, this system is 57.26 light-years from Sun. It is drifting further away with a radial velocity of +80 km/s.

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. 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.

HD 166066 is a solitary star located in the southern circumpolar constellation Octans. It has an apparent magnitude of 8.10, making it readily visible in binoculars, but not to the naked eye. The object is located 223 light years away from the Solar System, but is drifting away with a poorly constrained radial velocity of about 2.93 km/s.

HD 71334 is a Sun-like star 126.7 light years from the Sun. HD 150248 is a G-type star and an older solar analog. It is older than the sun at 8.1 billion years, compared to the sun at 4.6 billion years old. At 8.1 billion years old, HD 71334 has passed its stable burning stage. HD 71334 has a lower metallicity that the Sun. HD 71334 is found in the constellations of Puppis. Puppis is one of the 88 modern constellations recognized by the International Astronomical Union. HD 71334 has a brightness of 7.8.

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).

<span class="mw-page-title-main">HD 189567</span> Star in the constellation Pavo

HD 189567 is a star with a pair of orbiting exoplanets, located in the southern constellation of Pavo. It is also known as Gliese 776, CD-67 2385, and HR 7644. The star has an apparent visual magnitude of 6.07, which is bright enough for it to be dimly visible to the naked eye. It lies at a distance of 58 light years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of −10.5 km/s.

HD 30669 is a yellowish-orange hued star located in the southern constellation Caelum, the chisel. It has an apparent magnitude of 9.11, making it readily visible in small telescopes but not to the naked eye. The object is relatively close at a distance of 188 light years, based on parallax measurements from Gaia DR3. Its distance from the Solar System is rapidly increasing, having a heliocentric radial velocity of 66 km/s.

References

  1. 1 2 3 4 5 6 van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv: 0708.1752 . Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID   18759600. Vizier catalog entry
  2. 1 2 Vázquez, M.; Pallé, E.; Rodríguez, P. Montañés (2010). "Is Our Environment Special?". The Earth as a Distant Planet: A Rosetta Stone for the Search of Earth-Like Worlds . Astronomy and Astrophysics Library. Springer New York. pp.  391–418. doi:10.1007/978-1-4419-1684-6. ISBN   978-1-4419-1683-9. See table 9.1.
  3. ↑ Nordström, B.; et al. (May 2004). "The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ˜14 000 F and G dwarfs". Astronomy and Astrophysics. 418 (3): 989–1019. arXiv: astro-ph/0405198 . Bibcode:2004A&A...418..989N. doi:10.1051/0004-6361:20035959. S2CID   11027621.
  4. ↑ Do Nascimento, J. D. Jr.; Castro, M.; Meléndez, J.; Bazot, M.; Théado, S.; Porto de Mello, G. F.; de Medeiros, J. R. (July 2009). "Age and mass of solar twins constrained by lithium abundance". Astronomy and Astrophysics. 501 (2): 687–694. arXiv: 0904.3580 . Bibcode:2009A&A...501..687D. doi:10.1051/0004-6361/200911935. S2CID   9565600.
  5. 1 2 3 4 5 6 Takeda, Yoichi; Tajitsu, Akito (June 2009). "High-Dispersion Spectroscopic Study of Solar Twins: HIP 56948, HIP 79672, and HIP 100963". Publications of the Astronomical Society of Japan. 61 (3): 471–480. arXiv: 0901.2509 . Bibcode:2009PASJ...61..471T. doi:10.1093/pasj/61.3.471.
  6. 1 2 3 M. Mittag; K.-P. Schröder; A. Hempelmann; J.N. González-Pérez & J.H.M.M. Schmitt (3 September 2018). "Chromospheric activity and evolutionary age of the Sun and foursolar twins". Astronomy & Astrophysics . 591: A89. arXiv: 1607.01279v1 . doi:10.1051/0004-6361/201527542. S2CID   54765864.
  7. 1 2 Meléndez, Jorge; Iván Ramírez (2007). "HIP 56948: A Solar Twin with a Low Lithium Abundance (abstract)". Astrophysical Journal Letters . 669 (2): L89. arXiv: 0709.4290 . Bibcode:2007ApJ...669L..89M. doi:10.1086/523942. S2CID   15952981.
  8. ↑ Shiga, David (2007-10-03). "Sun's 'twin' an ideal hunting ground for alien life". New Scientist . Retrieved 2009-05-28.
  9. ↑ The Telegraph, retrieved 5 November 2010.
  10. ↑ New Scientist, retrieved 5 October 2009.
  11. ↑ "Light of the Dragon: Astronomers Discover Sun's Twin at McDonald Observatory". Astrobiology Magazine . 2007-11-13. Retrieved 2009-05-28.
  12. ↑ Mosher, Dave (2007-11-09). "Astronomers find the sun's long-lost twin: Happy reunion unlikely, as the star is about 200 light-years away". NBC News . Retrieved 2009-05-28.[ dead link ]
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