HD 40307
 Location of HD 40307 in the night sky. The star is marked within the red diamond below the word "Pictor". |
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| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) |
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|---|---|
| Constellation | Pictor |
| Right ascension | 05h 54m 04.2409s[1] |
| Declination | −60° 01′ 24.498″[1] |
| Apparent magnitude (V) | 7.17[1] |
| Characteristics | |
| Spectral type | K2.5V[1] |
| B−V color index | 0.93[1] |
| Astrometry | |
| Radial velocity (Rv) | +30.4 ± 0.2[1] km/s |
| Proper motion (μ) | RA: −51.76 [1] mas/yr Dec.: −60.44 [1] mas/yr |
| Parallax (π) | 77.95 ± 0.53[1] mas |
| Distance | 41.8 ± 0.3 ly (12.83 ± 0.09 pc) |
| Absolute magnitude (MV) | 6.63[note 1] |
| Details | |
| Mass | 0.75+0.03 −0.04[2] M☉ |
| Radius | 0.716 ± 0.010[3] R☉ |
| Surface gravity (log g) | 4.47 ± 0.16[4] |
| Luminosity (bolometric) | 0.23[4] L☉ |
| Luminosity (visual, LV) | 0.19[note 2] L☉ |
| Temperature | 4977 ± 59[4] K |
| Metallicity | [Fe/H] = −0.31 ± 0.03[4] |
| Rotation | ~48 days[4] |
| Rotational velocity (v sin i) | 3[2] km/s |
| Age | 1.2 (≥ 0.2) × 109[2] years |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
| ARICNS | data |
| Extrasolar Planets Encyclopaedia |
data |
HD 40307 is an orange (K-type) main sequence star located approximately 42 light-years away in the constellation of Pictor (the Easel), taking its primary name from its Henry Draper Catalogue designation. It is calculated to be slightly less massive than the Sun. HD 40307 was observed during or before 1900 as part of the Cape Photographic Durchmusterung.[5] In 2008, three extrasolar planets were discovered in orbit around it.[1][6]
Contents |
[edit] History and nomenclature
The designation HD 40307 is from the Henry Draper Catalogue. This catalogue was based on spectral classifications made between 1911 and 1915 by Annie Jump Cannon and her co-workers, and was published between 1918 and 1924.[7][8] Unlike stars like Sirius, Rigel, and Betelguese, HD 40307 does not have a common, colloquial name.
[edit] Characteristics
HD 40307, being a K-type star, emits orange-tinted light.[1] Additionally, at approximately three-fourths the Sun's radius and mass, it is smaller and less massive than the Sun.[2] HD 40307's temperature has been observed to be slightly under 5000 K. This is relatively high for a K-type star and approaches the temperatures normally found in G-type stars such as the Sun.[9]
The astronomers who discovered the planets orbiting HD 40307 suggested that the metallicities of stars determine whether or not the planetary bodies that orbit them will be terrestrial, like Earth, or gaseous, like Jupiter and Saturn.[10]
[edit] Distance and visibility
Despite its relative proximity to the Sun at 42 light-years, HD 40307, at an apparent magnitude of 7.17, is not visible to the naked eye.[11] It came within 6.4 light-years of the Sun about 413 thousand years ago.[12]
[edit] Planetary system
After spending five years observing the star,[13] the European Organisation for Astronomical Research in the Southern Hemisphere (ESO) announced that they had discovered three "Super-Earths" in orbit around HD 40307 in June 2008. All three planets were detected by the radial velocity method, using the HARPS spectrograph system.[14] All three planets orbit extremely near the star,[4] with the farthest member of the system located three times closer to HD 40307 than the planet Mercury is to the Sun.[15][note 3] The planets are more massive than the Earth, but probably less massive than Uranus and Neptune.[4] Dynamical analysis suggests that all three planets are gas giants, not terrestrial planets.[16] The radial velocity measurements also exhibit a linear trend, which may indicate the presence of an additional companion orbiting the star in a long-period orbit.[4]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity |
|---|---|---|---|---|
| b | ≥4.2 M⊕ | 0.047 | 4.3115 ± 0.0006 | 0.0 |
| c | ≥6.8 M⊕ | 0.081 | 9.620 ± 0.002 | 0.0 |
| d | ≥9.2 M⊕ | 0.134 | 20.46 ± 0.01 | 0.0 |
[edit] See also
 |
Book: HD 40307 |
| Wikipedia books are collections of articles that can be downloaded or ordered in print. | |
- List of extrasolar planets
- Other stars with planets discovered in June 2008:
[edit] Notes
- ^ From apparent magnitude and parallax:
- ^ Using the absolute visual magnitude of HD 40307
and the absolute visual magnitude of the Sun 
, the visual luminosity can be calculated by 
- ^ Mercury orbits at approx. 0.39 AU
and the absolute visual magnitude of the Sun 
, the visual luminosity can be calculated by 
[edit] References
- ^ a b c d e f g h i j k l HD 40307, entry, SIMBAD. Accessed online June 18, 2008.
- ^ a b c d HD 40307, database entry, Geneva-Copenhagen Survey of Solar neighbourhood, J. Holmberg et al., 2007, CDS database V/117A, accessed November 19, 2008; described in The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ~14 000 F and G dwarfs, B. Nordström, M. Mayor, J. Andersen, J. Holmberg, F. Pont, B. R. Jørgensen, E. H. Olsen, S. Udry, and N. Mowlavi, Astronomy and Astrophysics 418 (May 2004), pp. 989–1019, Bibcode: 2004A&A...418..989N, doi:10.1051/0004-6361:20035959.
- ^ HD 40307, entry, CDS database J/A+A/450/735; described in Effective temperature scale and bolometric corrections from 2MASS photometry, E. Masana, C. Jordi, and I. Ribas, Astronomy and Astrophysics 450, #2 (May 2006), pp. 735–746. Bibcode: 2006A&A...450..735M. doi:10.1051/0004-6361:20054021.
- ^ a b c d e f g h i M. Mayor, S. Udry, C. Lovis, F. Pepe, D. Queloz, W. Benz, J.-L. Bertaux, F. Bouchy, C. Mordasini, D. Segransan (2009). "The HARPS search for southern extra-solar planets. XIII. A planetary system with 3 Super-Earths (4.2, 6.9, & 9.2 Earth masses)". Submitted to Astronomy and Astrophysics 493 (2): 639. arXiv:0806.4587. Bibcode 2009A&A...493..639M. doi:10.1051/0004-6361:200810451.
- ^ CPD−60 508, database entry, Cape Photographic Durchmusterung (CPD), D. Gill and J. C. Kapetyn, 1895–1900, CDS ID I/108.
- ^ Three super-Earths found around one star, Jeanna Bryner, MSNBC, June 16, 2008. Accessed on line June 18, 2008.
- ^ pp. 214–215 in The Henry Draper Memorial, Annie J. Cannon, Journal of the Royal Astronomical Society of Canada 9, #5 (May–June 1915), pp. 203–215, Bibcode: 1915JRASC...9..203C.
- ^ The Henry Draper Catalogue, Annie J. Cannon and Edward C. Pickering, Annals of Harvard College Observatory;
hours 0 to 3, 91 (1918), Bibcode: 1918AnHar..91....1C;
hours 4 to 6, 92 (1918), Bibcode: 1918AnHar..92....1C;
hours 7 to 8, 93 (1919), Bibcode: 1919AnHar..93....1C;
hours 9 to 11, 94 (1919), Bibcode: 1919AnHar..94....1C;
hours 12 to 14, 95 (1920), Bibcode: 1920AnHar..95....1C;
hours 15 to 16, 96 (1921), Bibcode: 1921AnHar..96....1C;
hours 17 to 18, 97 (1922), Bibcode: 1922AnHar..97....1C;
hours 19 to 20, 98 (1923), Bibcode: 1923AnHar..98....1C;
hours 21 to 23, 99 (1924), Bibcode: 1924AnHar..99....1C. - ^ "Properties of Stars". Astronomy Notes. Jodrell Bank Centre for Astrophysics. 2007. Archived from the original on June 22, 2008. http://web.archive.org/web/20080622012045/http://www.jb.man.ac.uk/distance/strobel/starprop/strpropd.htm. Retrieved 27 November 2008.
- ^ M. Mayor, S. Udry, C. Lovis, F. Pepe, D. Queloz, W. Benz, J.-L. Bertaux, F. Bouchy, C. Mordasini, D. Segransan (2009). "The HARPS search for southern extra-solar planets. XIII. A planetary system with 3 Super-Earths (4.2, 6.9, & 9.2 Earth masses)". Submitted to Astronomy & Astrophysics 493 (2): 639. arXiv:0806.4587. Bibcode 2009A&A...493..639M. doi:10.1051/0004-6361:200810451.
- ^ "Stellar Magnitudes". Astrophysics 162 Unit. University of Tennessee. 2008. http://csep10.phys.utk.edu/astr162/lect/stars/magnitudes.html. Retrieved 20 November 2008.
- ^ Bobylev, Vadim V. (March 2010). "Searching for Stars Closely Encountering with the Solar System". Astronomy Letters 36 (3): 220–226. arXiv:1003.2160. Bibcode 2010AstL...36..220B. doi:10.1134/S1063773710030060.
- ^ "HD 40307 / CD-60 1303". SolStation. Sol Company. 2008. http://www.solstation.com/stars2/hd40307.htm. Retrieved 27 November 2008.
- ^ "Trio of 'super-Earths' discovered". BBC news. 2008-06-16. http://news.bbc.co.uk/1/hi/sci/tech/7457307.stm. Retrieved 2008-06-16.
- ^ "Mercury Fact Sheet". NASA Goddard Space Flight Center. November 30, 2007. http://nssdc.gsfc.nasa.gov/planetary/factsheet/mercuryfact.html. Retrieved 2008-11-12.
- ^ Barnes, Rory; Jackson, Brian; Raymond, Sean N.; West, Andrew A.; Greenberg, Richard (January 13, 2009). "The HD 40307 Planetary System: Super-Earths or Mini-Neptunes?". The Astrophysical Journal 695 (2): 1006. arXiv:0901.1698. Bibcode 2009ApJ...695.1006B. doi:10.1088/0004-637X/695/2/1006.
[edit] External links
- A Trio of Super-Earths: A harvest of low-mass exoplanets discovered with HARPS, press release, European Southern Observatory, ESO 19/08, June 16, 2008.
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