47 Ursae Majoris

47 Ursae Majoris (abbreviated 47 UMa), formally named Chalawan /ˈtʃɑːləwən/,[7][8] is a yellow dwarf star approximately 46 light-years[1] from Earth in the constellation of Ursa Major. As of 2011, three extrasolar planets (designated 47 Ursae Majoris b, c and d; the first two later named Taphao Thong and Taphao Kaew) are believed to orbit the star.

The star is located fairly close to the Solar System: according to astrometric measurements made by the Hipparcos astrometry satellite, it exhibits a parallax of 71.11 milliarcseconds, corresponding to a distance of 45.913 light-years.[1] With an apparent magnitude of +5.03, it is visible to the naked eye and its absolute magnitude of +4.29 implies a visual luminosity around 60% greater than the Sun. A solar analog, with a spectral type of G1V, it has a similar mass to that of the Sun but is slightly hotter at around 5,882 K.[3] and slightly more metal-rich with around 110% of the solar abundance of iron.

Like the Sun, 47 Ursae Majoris is on the main sequence, converting hydrogen to helium in its core by nuclear fusion. Based on its chromospheric activity, the star may be around 6,000 million years old, though evolutionary models suggest an older age of around 8,700 million years.[6] Other studies have yielded estimates of 4,400 and 7,000 million years for the star.[9]

47 Ursae Majoris
47 UMa-starmap

Location of 47 Ursae Majoris in Ursa Major.
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ursa Major
Right ascension  10h 59m 27.973s[1]
Declination +40° 25′ 48.92″[1]
Apparent magnitude (V) +5.03
Spectral type G1V
U−B color index 0.13
B−V color index 0.61
Radial velocity (Rv)+12.6 km/s
Proper motion (μ) RA: −317.01±0.22[1] mas/yr
Dec.: 54.64±0.20[1] mas/yr
Parallax (π)71.11 ± 0.25[1] mas
Distance45.9 ± 0.2 ly
(14.06 ± 0.05 pc)
Absolute magnitude (MV)4.41[2]
Mass1.08[3] M
Radius1.172 ± 0.111 [4] R
Luminosity1.48[note 1] L
Surface gravity (log g)4.377[3] cgs
Temperature5887 ± 3.8 [5] K
Metallicity110% solar[3]
Rotational velocity (v sin i)2.80[3] km/s
Age6.03[6] Gyr
Other designations
Chalawan, BD+41°2147, FK5 1282, GC 15087, GCTP 2556.00, Gliese 407, HD 95128, HIP 53721, HR 4277, LTT 12934, SAO 43557
Database references
SIMBADThe star
planet b
planet c
planet d
Exoplanet Archivedata
Extrasolar Planets


47 Ursae Majoris is the Flamsteed designation. On their discoveries the planets were successively designated 47 Ursae Majoris b, c and d.

In July 2014 the International Astronomical Union launched a process for giving proper names to certain exoplanets and their host stars.[10] The process involved public nomination and voting for the new names.[11] In December 2015, the IAU announced the winning names were Chalawan for this star and Taphao Thong and Taphao Kaew for two of the planets (b and c, respectively).[12] The winning names were submitted by the Thai Astronomical Society, Thailand. Chalawan (Thai: ชาละวัน  [t͡ɕʰāːlāwān]) is a mythological crocodile king from the Thai folktale Krai Thong and Taphaothong and Taphaokaeo are two sisters associated with the tale.[13] ('Chalawan' is also the name given to an extinct genus of crocodylian. It contains a single species, Chalawan thailandicus.[14])

In 2016, the IAU organized a Working Group on Star Names (WGSN)[15] to catalog and standardize proper names for stars. In its first bulletin of July 2016,[16] the WGSN explicitly recognized the names of exoplanets and their host stars approved by the Executive Committee Working Group Public Naming of Planets and Planetary Satellites, including the names of stars adopted during the 2015 NameExoWorlds campaign. This star is now so entered in the IAU Catalog of Star Names.[7]

Planetary system

In 1996 an exoplanet (47 UMa b) was announced in orbit around 47 Ursae Majoris by Geoffrey Marcy and R. Paul Butler. The discovery was made by observing the Doppler shift of the star's spectrum corresponding to changes in the star's radial velocity as the planet's gravity pulled it around.[17] The planet was the first long-period extrasolar planet discovered. Unlike the majority of known such planets, it has a low-eccentricity orbit. The planet is at least 2.53 times the mass of Jupiter and takes 1,078 days or 2.95 years to orbit its star. If it were to be located in the Solar System, it would lie between the orbits of Mars and Jupiter.[18]

Orbits of the planets in the 47 Ursae Majoris system. The orbit of 47 UMa d is currently quite uncertain; both it and that of 47 UMa c may be circular.

In 2001, preliminary astrometric measurements made by the Hipparcos probe suggested the orbit of 47 UMa b is inclined at an angle of 63.1° to the plane of the sky, implying the planet's true mass is around 2.9 times that of Jupiter.[19] However, subsequent analysis suggested the Hipparcos measurements were not precise enough to accurately determine the orbits of substellar companions, and the inclination and true mass remain unknown.[20]

A second planet (47 UMa c) was announced in 2002 by Debra Fischer, Geoffrey Marcy, and R. Paul Butler. The discovery was made using the same radial velocity method. According to Fischer et al., the planet takes around 2,391 days or 6.55 years to complete an orbit. This configuration is similar to the configuration of Jupiter and Saturn in the Solar System, with the orbital ratio (close to 5:2), and mass ratio roughly similar.[21] Subsequent measurements failed to confirm the existence of the second planet, and it was noted that the dataset used to determine its existence left the planet's parameters "almost unconstrained".[22] Analysis of a longer dataset spanning over 6,900 days suggests that while a second planet in the system is likely, periods near 2,500 days have a high false alarm probability, and the best fit model gives an orbital period of 7,586 days at a distance of 7.73 AU from the star. Nevertheless, the parameters of the second planet are still highly uncertain.[23] On the other hand, the Catalog of Nearby Exoplanets gives a period of 2,190 days, which would put the planets close to a 2:1 ratio of orbital periods, though the reference for these parameters is uncertain: the original Fischer et al. paper is cited as a reference in spite of the fact that it gives different parameters,[21][24] though this solution has been adopted by the Extrasolar Planets Encyclopaedia.[25]

In 2010, the discovery of a third planet (47 UMa d) was made by using the Bayesian Kepler Periodogram. Using this model of this planetary system it was determined that it is 100,000 times more likely to have three planets than two planets. This discovery was announced by Debra Fischer and P.C. Gregory. This 1.64 MJ planet has an orbital period of 14,002 days or 38.33 years and a semi-major axis of 11.6 AU with a moderate eccentricity of 0.16.[18] It would be the longest-period planet discovered by the radial velocity method, although longer-period planets had previously been discovered by direct imaging and pulsar timing.

Simulations suggest that the inner part of the habitable zone of 47 Ursae Majoris could host a terrestrial planet in a stable orbit, though the outer regions of the habitable zone would be disrupted by the gravitational influence of the planet 47 UMa b.[26] However, the presence of a giant planet within 2.5 AU of the star may have disrupted planet formation in the inner system, and reduced the amount of water delivered to inner planets during accretion.[27] This may mean any terrestrial planets orbiting in the habitable zone of 47 Ursae Majoris are likely to be small and dry. As of 2008, there have been two METI messages sent to 47 Ursae Majoris. Both were transmitted from Eurasia's largest radar — 70-meter (230-foot) Eupatoria Planetary Radar. The first message, the Teen Age Message, was sent on September 3, 2001, and it will arrive at 47 Ursae Majoris in July 2047. The second message, Cosmic Call 2, was sent on July 6, 2003, and it will arrive at 47 Ursae Majoris in May 2049.[28]

The 47 Ursae Majoris planetary system[18]
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
b (Taphao Thong) >2.53+0.07
2.10 ± 0.02 1078 ± 2 0.032 ± 0.014
c (Taphao Kaew) >0.540+0.066
3.6 ± 0.1 2391+100
d >1.64+0.29

Because of its planetary system, 47 Ursae Majoris was listed as one of the top 100 target stars for NASA's former Terrestrial Planet Finder mission.[29]

See also


  1. ^ From , where is the luminosity, is the radius, is the effective surface temperature and is the Stefan–Boltzmann constant


  1. ^ a b c d e f g van Leeuwen, F. (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. Vizier catalog entry
  2. ^ Elgarøy, Øystein; Engvold, Oddbjørn; et al. (March 1999), "The Wilson-Bappu effect of the MgII K line - dependence on stellar temperature, activity and metallicity", Astronomy and Astrophysics, 343: 222–228, Bibcode:1999A&A...343..222E
  3. ^ a b c d e "Stars Table". Catalog of Nearby Exoplanets. Archived from the original on 17 October 2008. Retrieved 2008-10-04.
  4. ^ G. T. van Belle; K. von Braun (2009). "Directly Determined Linear Radii and Effective Temperatures of Exoplanet Host Stars". Astrophysical Journal. 694 (2): 1085–1098. arXiv:0901.1206. Bibcode:2009ApJ...694.1085V. doi:10.1088/0004-637X/694/2/1085.
  5. ^ V. V. Kovtyukh; Soubiran, C.; et al. (2003). "High precision effective temperatures for 181 F-K dwarfs from line-depth ratios". Astronomy and Astrophysics. 411 (3): 559–564. arXiv:astro-ph/0308429. Bibcode:2003A&A...411..559K. doi:10.1051/0004-6361:20031378.
  6. ^ a b C. Saffe; Gómez, M.; et al. (2005). "On the Ages of Exoplanet Host Stars". Astronomy and Astrophysics. 443 (2): 609–626. arXiv:astro-ph/0510092. Bibcode:2005A&A...443..609S. doi:10.1051/0004-6361:20053452.
  7. ^ a b "IAU Catalog of Star Names". Retrieved 28 July 2016.
  8. ^ Thai Astronomical Society, Chalawan, Taphao Thong, Taphao Kaew – First Thai Exoworld Names
  9. ^ E. E. Mamajek; L. A. Hillenbrand (2008). "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics". Astrophysical Journal. 687 (2): 1264–1293. arXiv:0807.1686. Bibcode:2008ApJ...687.1264M. doi:10.1086/591785.
  10. ^ NameExoWorlds: An IAU Worldwide Contest to Name Exoplanets and their Host Stars. IAU.org. 9 July 2014
  11. ^ NameExoWorlds The Process
  12. ^ Final Results of NameExoWorlds Public Vote Released, International Astronomical Union, 15 December 2015.
  13. ^ NameExoWorlds The Approved Names
  14. ^ Martin, J. E.; Lauprasert, K.; et al. (2013). Angielczyk, Kenneth (ed.). "A large pholidosaurid in the Phu Kradung Formation of north-eastern Thailand". Palaeontology. 57: 757–769. doi:10.1111/pala.12086.
  15. ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  16. ^ "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016.
  17. ^ R. P. Butler; Marcy, Geoffrey W. (1996). "A Planet Orbiting 47 Ursae Majoris". Astrophysical Journal Letters. 464 (2): L153–L156. Bibcode:1996ApJ...464L.153B. doi:10.1086/310102.
  18. ^ a b c P. C. Gregory; D. A. Fischer (2010). "A Bayesian periodogram finds evidence for three planets in 47 Ursae Majoris". Monthly Notices of the Royal Astronomical Society. 403 (2): 731–747. arXiv:1003.5549. Bibcode:2010MNRAS.403..731G. doi:10.1111/j.1365-2966.2009.16233.x.
  19. ^ I. Han; D. C. Black; et al. (2001). "Preliminary Astrometric Masses for Proposed Extrasolar Planetary Companions". Astrophysical Journal Letters. 548 (1): L57–L60. Bibcode:2001ApJ...548L..57H. doi:10.1086/318927.
  20. ^ D. Pourbaix; F. Arenou (2001). "Screening the Hipparcos-based astrometric orbits of sub-stellar objects". Astronomy and Astrophysics. 372 (3): 935–944. arXiv:astro-ph/0104412. Bibcode:2001A&A...372..935P. doi:10.1051/0004-6361:20010597.
  21. ^ a b D. A. Fischer; Marcy, Geoffrey W.; et al. (2002). "A Second Planet Orbiting 47 Ursae Majoris". Astrophysical Journal. 564 (2): 1028–1034. Bibcode:2002ApJ...564.1028F. CiteSeerX doi:10.1086/324336.
  22. ^ D. Naef; Mayor, M.; et al. (2004). "The ELODIE survey for northern extra-solar planets. III. Three planetary candidates detected with ELODIE". Astronomy and Astrophysics. 414: 351–359. arXiv:astro-ph/0310261. Bibcode:2004A&A...414..351N. doi:10.1051/0004-6361:20034091.
  23. ^ R. A. Wittenmyer; M. Endl; et al. (2007). "Long-Period Objects in the Extrasolar Planetary Systems 47 Ursae Majoris and 14 Herculis". Astrophysical Journal. 654 (1): 625–632. arXiv:astro-ph/0609117. Bibcode:2007ApJ...654..625W. doi:10.1086/509110.
  24. ^ "Planets Table". Catalog of Nearby Exoplanets. Archived from the original on 21 September 2008. Retrieved 2008-10-04.
  25. ^ Jean Schneider (2011). "Notes for Planet 47 Uma c". Extrasolar Planets Encyclopaedia. Retrieved 3 October 2011.
  26. ^ B. Jones; Underwood, David R.; et al. (2005). "Prospects for Habitable "Earths" in Known Exoplanetary Systems". Astrophysical Journal. 622 (2): 1091–1101. arXiv:astro-ph/0503178. Bibcode:2005ApJ...622.1091J. doi:10.1086/428108.
  27. ^ S. Raymond (2006). "The Search for other Earths: limits on the giant planet orbits that allow habitable terrestrial planets to form". Astrophysical Journal Letters. 643 (2): L131–134. arXiv:astro-ph/0605136. Bibcode:2006ApJ...643L.131R. doi:10.1086/505596.
  28. ^ А. Л. Зайцев (7 June 2004). Передача и поиски разумных сигналов во Вселенной. Пленарный доклад на Всероссийской астрономической конференции ВАК-2004 "Горизонты Вселенной", Москва, МГУ (in Russian).
  29. ^ "#72 HIP 53721". TPF-C Top 100. Retrieved 22 July 2006.

External links

Coordinates: Sky map 10h 59m 28.0s, +40° 25′ 49″

14 Herculis

14 Herculis or 14 Her is the Flamsteed designation of a K-type main-sequence star approximately 58.5 light-years away in the constellation Hercules. Because of its apparent magnitude, the star cannot be seen with the naked eye. As of 2006, it is thought that 14 Herculis has two extrasolar planets in orbit around the star.

14 Herculis c

14 Herculis c or 14 Her c is an extrasolar planet approximately 58.5 light-years away in the constellation of Hercules. The planet was found orbiting the star 14 Herculis, with a mass that would likely make the planet a gas giant roughly the same size as Jupiter but much more massive. This planet was discovered on November 17, 2005 and confirmed on November 2, 2006. According to a recent analysis, the existence of a second planet in the 14 Herculis system is "clearly" supported by the evidence, but the planet's parameters are not precisely known. It may be in a 4:1 resonance with the inner planet 14 Herculis b.


2069 (MMLXIX)

will be a common year starting on Tuesday of the Gregorian calendar, the 2069th year of the Common Era (CE) and Anno Domini (AD) designations, the 69th year of the 3rd millennium, the 69th year of the 21st century, and the 10th and last year of the 2060s decade.

47 Ursae Majoris b

47 Ursae Majoris b (abbreviated 47 UMa b), formally named Taphao Thong , is an extrasolar planet approximately 46 light-years from Earth in the constellation of Ursa Major. The planet was discovered located in a long-period orbit around the star 47 Ursae Majoris in January 1996 and as of 2011 it is the innermost of three known planets in its planetary system. It has a mass at least 2.53 times that of Jupiter.

47 Ursae Majoris c

47 Ursae Majoris c (abbreviated 47 UMa c), formally named Taphao Kaew , is an extrasolar planet approximately 46 light-years from Earth in the constellation of Ursa Major. The planet was discovered located in a long-period around the star 47 Ursae Majoris. Its orbit lasts 6.55 years and the planet has a mass at least 0.540 times that of Jupiter.

47 Ursae Majoris d

47 Ursae Majoris d (sometimes abbreviated 47 Uma d) is an extrasolar planet approximately 46 light-years away in the constellation of Ursa Major. The planet was discovered located in a long-period orbit (38 years) around the star 47 Ursae Majoris. As of 2011, it is the outermost of three known planets in its planetary system. It has a mass of at least 1.64 times that of Jupiter. It is the longest-period planet detected by Doppler spectroscopy. The evidence of this planet was found by Bayesian Kepler periodogram in March 2010.

70 Virginis b

70 Virginis b (abbreviated 70 Vir b) is an extrasolar planet approximately 60 light-years away in the constellation of Virgo. Announced in 1996 by Geoffrey Marcy and R. Paul Butler, 70 Virginis was one of the first stars confirmed to have planets orbiting it. When first announced, 70 Virginis b was considered to be within its star's habitable zone (preferably in the "Goldilocks zone"), but it was later confirmed that the planet has an eccentric orbit, closer to its parent.

Chalawan (disambiguation)

Chalawan is a character from the Thai folktale Krai Thong. The name may also refer to:

Chalawan (genus), an extinct genus of pholidosaurid mesoeucrocodylian

Chalawan, an alternative name for 47 Ursae Majoris, a star in the constellation of Ursa Major

Coyote (novel)

Coyote (2002) a science fiction novel by American writer Allen Steele. The book is a compilation of some of Steele’s short stories into one novel. Perspective is taken from many of the major characters of the book.

Coyote is part of a trilogy, that also includes the sequels Coyote Rising and Coyote Frontier. There are three spinoff novels, Spindrift, Galaxy Blues, and Hex, which are set in the same universe, although not directly tied to the events in Coyote. The series is continued by the Coyote Chronicles, a two book duology, including Coyote Horizon, released in March 2009 and Coyote Destiny, which was released on March 2, 2010.

Dmitri Novgorodsky

Dmitri Novgorodsky is a classical pianist. He is the first Moscow Tchaikovsky Conservatory graduate in piano performance and the first Russian-Soviet musician who has earned the Doctor of Musical Arts in Piano Performance degree from Yale University.

Lemarean Calendar

The Lemarean Calendar is used by the colonists on the moon Coyote as described in the science fiction trilogy of the same name by author Allen Steele. The trilogy, including Coyote (2002), Coyote Rising (2004), and Coyote Frontier (2005), describes the exploration and settlement of a habitable moon orbiting a ringed jovian in the 47 Ursae Majoris system.

List of exoplanets detected by radial velocity

The following is a list of 456 extrasolar planets that were only detected by radial velocity method –– 31 confirmed and 323 candidates, sorted by orbital periods. Since none of these planets are transiting or directly observed, they do not have measured radii and generally their masses are only minimum. The true masses can be determined when astrometry calculates the inclination of the orbit.

There are 160 members of the multi-planet systems –– 21 confirmed and 139 candidates.

List of exoplanets discovered before 2000

This is a List of exoplanets discovered before 2000.

For exoplanets detected only by radial velocity, the mass value is actually a lower limit. (See Minimum mass for more information)


OGLE-2006-BLG-109Lb is an extrasolar planet approximately 4,920 light-years away in the constellation of Sagittarius. The planet was detected orbiting the star OGLE-2006-BLG-109L in 2008 by a research team using Microlensing.


OGLE-2006-BLG-109Lc is an extrasolar planet approximately 4,920 light-years away in the constellation of Sagittarius. The planet was detected orbiting the star OGLE-2006-BLG-109L in 2008 by a research team using Microlensing. The host star is about 50% the mass of the Sun and the planet is about 90% the mass of Saturn.


OGLE-2007-BLG-349(AB)b is a circumbinary extrasolar planet about 8,000 light-years away in the constellation of Sagittarius. It is the first circumbinary exoplanet to be discovered using the microlensing method of detecting exoplanets.

Sudarsky's gas giant classification

Sudarsky's classification of gas giants for the purpose of predicting their appearance based on their temperature was outlined by David Sudarsky and colleagues in the paper Albedo and Reflection Spectra of Extrasolar Giant Planets and expanded on in Theoretical Spectra and Atmospheres of Extrasolar Giant Planets, published before any successful direct or indirect observation of an extrasolar planet atmosphere was made. It is a broad classification system with the goal of bringing some order to the likely rich variety of extrasolar gas-giant atmospheres.

Gas giants are split into five classes (numbered using Roman numerals) according to their modeled physical atmospheric properties. In the Solar System, only Jupiter and Saturn are within the Sudarsky classification, and both are Class I.

The appearance of planets that are not gas giants cannot be predicted by the Sudarsky system, for example terrestrial planets such as Earth and Venus, HD 85512 b (3.6 Earth masses) and OGLE-2005-BLG-390Lb (5.5 Earth masses), or ice giants such as Uranus (14 Earth masses) and Neptune (17 Earth masses).

Ursa Major

Ursa Major (; also known as the Great Bear) is a constellation in the northern sky, whose associated mythology likely dates back into prehistory. Its Latin name means "greater (or larger) she-bear," referring to and contrasting it with nearby Ursa Minor, the lesser bear. In antiquity, it was one of the original 48 constellations listed by Ptolemy in the 2nd century AD. Today it is the third largest of the 88 modern constellations.

Ursa Major is primarily known from the asterism of its main seven stars, which has been called the "Big Dipper," "the Wagon," "Charles's Wain," or "the Plough," among other names. In particular, the Big Dipper's stellar configuration mimics the shape of the "Little Dipper." Its two brightest stars, named Dubhe and Merak (α Ursae Majoris and β Ursae Majoris), can be used as the navigational pointer towards the place of the current northern pole star, Polaris in Ursa Minor.

Ursa Major, along with asterisms that incorporate or comprise it, is significant to numerous world cultures, often as a symbol of the north. Its depiction on the flag of Alaska is a modern example of such symbolism.

Ursa Major is visible throughout the year from most of the northern hemisphere, and appears circumpolar above the mid-northern latitudes. From southern temperate latitudes, the main asterism is invisible, but the southern parts of the constellation can still be viewed.

47 Ursae Majoris system
Stars of Ursa Major


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