Its two main constituents are designated Delta Cancri A and B. A is itself a binary star whose components are Delta Cancri Aa (formally named Asellus Australis/əˈsɛləsɔːsˈtreɪlɪs/, the traditional name of the entire system)[6] and Ab.
The star system is 0.08 degree north of the ecliptic, so it can be occulted by the Moon and more rarely by planets; it is occulted (eclipsed) by the sun from about 31 July to 2 August.[7] Thus the star can be viewed the whole night, crossing the sky at the start of February.
δ Cancri (Latinised to Delta Cancri) is the system's Bayer designation. The designations of the two constituents Delta Cancri A and B, and those of A's components - Delta Cancri Aa and Ab - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[8]
It bore the traditional name Asellus Australis which is Latin for "southern donkey colt".[9] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[10] to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[11] It approved the name Asellus Australis for the component Delta Cancri Aa on 6 November 2016 and it is now so included in the List of IAU-approved Star Names.[6] Together with Gamma Cancri, it formed the Aselli, flanking Praesepe.[9]
As Arkū-sha-nangaru-sha-shūtu, which means "the southeast star in the Crab", it marked the 13th ecliptic station of the ancient Babylonians.[9]
Delta Cancri was involved in the first recorded occultation by Jupiter:
"The most ancient observation of Jupiter which we are acquainted with is that reported by Ptolemy in book X, chap. iii (sic), of the Almagest, ...when the planet eclipsed the star known as (Delta) Cancri. This observation was made on September 3, B.C. 240, about 18h on the meridian of Alexandria."
— Allen, 1898, quoting from Hind's The Solar System).
Delta Cancri also marks the famous open star cluster Praesepe (or the Beehive Cluster, also known as Messier 44). In ancient times M44 was used as a weather gauge as the following Greek rhyme from Aratos' Prognostica reveals:
A murky manger with both stars
Shining unaltered is a sign of rain.
While if the northern Ass is dimmed
By vaporous shroud, he of the south gleam radiant,
Expect a south wind: the vaporous shroud and radiance
Exchanging stars harbinger Boreas.
— Allen, 1898
The meaning of this verse is that if Asellus Borealis or Gamma Cancris[14] is hidden by clouds, the wind will be from the south and that situation will be reversed if Asellus Australis is obscured. There is some doubt however as to the accuracy of this as Allen notes: "Our modern Weather Bureau would probably tell us that if one of these stars were thus concealed, the other also would be." (Allen, 1898)
But Delta Cancri also acts as more than just a dubious weather guide: it is a reliable signpost for finding the vividly red star X Cancri as Patrick Moore notes in his guidebook Stars of the Southern Skies:
“In the same binocular field with Delta [Cancri] you will find one of the reddest stars in the sky: X Cancri. It is a semi-regular variable; at maximum it rises to magnitude 5 and it never falls below 7.3 so that it can always be seen with binoculars. It looks rather like a tiny glowing coal.”
— Page 146, Moore, 1994.
Delta Cancri also marks the radiant of the Delta Cancrids meteor shower.
In 1876, the possibility of Delta Cancri having a companion star was proposed.[15]
Referencesedit
^ abcdevan 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, S2CID 18759600.
^ abcJohnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
^ abcdeLuck, R. Earle (September 2015), "Abundances in the Local Region. I. G and K Giants", The Astronomical Journal, 150 (3): 23, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88, S2CID 118505114, 88.
^ abcdeMassarotti, Alessandro; et al. (January 2008), "Rotational and radial velocities for a sample of 761 HIPPARCOS giants and the role of binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209
^Soubiran, C.; et al. (March 2008), "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants", Astronomy and Astrophysics, 480 (1): 91–101, arXiv:0712.1370, Bibcode:2008A&A...480...91S, doi:10.1051/0004-6361:20078788, S2CID 16602121.
^ ab"Naming Stars". IAU.org. Retrieved 16 December 2017.
^In the Sky Earth astronomy reference utility showing the ecliptic and relevant date as at J2000 - present
^Hessman, F. V.; Dhillon, V. S.; Winget, D. E.; Schreiber, M. R.; Horne, K.; Marsh, T. R.; Guenther, E.; Schwope, A.; Heber, U. (2010). "On the naming convention used for multiple star systems and extrasolar planets". arXiv:1012.0707 [astro-ph.SR].
^亮星中英對照表 [English-Chinese Glossary of Bright Stars]. Hong Kong Space Museum (in Chinese). Retrieved February 3, 2018. Asellus Australis
^Kaler, 2009:. Archived from the original on 2011-07-16.
^Burnham, S. W. (1878). "The companion to delta Cancri". The Observatory. 2: 60. Bibcode:1878Obs.....2...60B.
Booksedit
Richard H. Allen (28 February 2013). Star Names: Their Lore and Meaning. Courier Corporation. ISBN978-0-486-13766-7.
Robert Burnham (15 April 2013). Burnham's Celestial Handbook, Volume One: An Observer's Guide to the Universe Beyond the Solar System. Courier Corporation. pp. 340–. ISBN978-0-486-31902-5.
James B. Kaler (20 November 2006). The Cambridge Encyclopedia of Stars. Cambridge University Press. ISBN978-0-521-81803-2.
Lloyd Motz; Carol Nathanson (1 November 1988). The constellations. Doubleday. ISBN9780385176002.
Patrick Moore (13 October 1998). Atlas of the Universe. Cambridge University Press. ISBN978-0-521-64210-1.
delta, cancri, cancri, abbreviated, delta, double, star, about, light, years, from, constellation, cancer, cancrilocation, cancri, circled, observation, dataepoch, j2000, equinox, j2000, constellation, cancer, right, ascension, 09921s, declination, 5034, appar. Delta Cancri d Cancri abbreviated Delta Cnc d Cnc is a double star about 180 light years from the Sun in the constellation of Cancer d CancriLocation of d Cancri circled Observation dataEpoch J2000 0 Equinox J2000 0 Constellation Cancer Right ascension 08h 44m 41 09921s 1 Declination 18 09 15 5034 1 Apparent magnitude V 3 94 2 Characteristics Spectral type K0 III 3 U B color index 0 99 2 B V color index 1 08 2 AstrometryRadial velocity Rv 16 39 0 25 4 km sProper motion m RA 17 67 1 mas yr Dec 229 26 1 mas yrParallax p 24 98 0 24 mas 1 Distance131 1 ly 40 0 0 4 pc Absolute magnitude MV 0 843 5 DetailsMass1 71 3 M Radius11 4 R Luminosity52 3 L Surface gravity log g 2 7 4 cgsTemperature4 637 27 3 KMetallicity Fe H 0 13 4 dexRotational velocity v sin i 2 8 4 km sAge2 45 3 Gyr Other designationsAsellus Australis d Cnc 47 Cnc BD 18 2027 FK5 326 GC 12022 HD 74442 HIP 42911 HR 3461 SAO 98087 ADS 6967 CCDM 08447 1809 Database referencesSIMBADdata Its two main constituents are designated Delta Cancri A and B A is itself a binary star whose components are Delta Cancri Aa formally named Asellus Australis e ˈ s ɛ l e s ɔː s ˈ t r eɪ l ɪ s the traditional name of the entire system 6 and Ab The star system is 0 08 degree north of the ecliptic so it can be occulted by the Moon and more rarely by planets it is occulted eclipsed by the sun from about 31 July to 2 August 7 Thus the star can be viewed the whole night crossing the sky at the start of February Contents 1 Nomenclature 2 Observations 3 References 3 1 BooksNomenclature editd Cancri Latinised to Delta Cancri is the system s Bayer designation The designations of the two constituents Delta Cancri A and B and those of A s components Delta Cancri Aa and Ab derive from the convention used by the Washington Multiplicity Catalog WMC for multiple star systems and adopted by the International Astronomical Union IAU 8 It bore the traditional name Asellus Australis which is Latin for southern donkey colt 9 In 2016 the International Astronomical Union organized a Working Group on Star Names WGSN 10 to catalogue and standardize proper names for stars The WGSN decided to attribute proper names to individual stars rather than entire multiple systems 11 It approved the name Asellus Australis for the component Delta Cancri Aa on 6 November 2016 and it is now so included in the List of IAU approved Star Names 6 Together with Gamma Cancri it formed the Aselli flanking Praesepe 9 As Arku sha nangaru sha shutu which means the southeast star in the Crab it marked the 13th ecliptic station of the ancient Babylonians 9 In Chinese astronomy Ghost Chinese 鬼宿 pinyin Guǐ Xiu refers to an asterism consisting of Theta Cancri Eta Cancri Gamma Cancri and Delta Cancri 12 Delta Cancri itself is known as the fourth star of Ghost Chinese 鬼宿四 pinyin Guǐ Xiu si 13 Observations editDelta Cancri was involved in the first recorded occultation by Jupiter The most ancient observation of Jupiter which we are acquainted with is that reported by Ptolemy in book X chap iii sic of the Almagest when the planet eclipsed the star known as Delta Cancri This observation was made on September 3 B C 240 about 18h on the meridian of Alexandria Allen 1898 quoting from Hind s The Solar System Delta Cancri also marks the famous open star cluster Praesepe or the Beehive Cluster also known as Messier 44 In ancient times M44 was used as a weather gauge as the following Greek rhyme from Aratos Prognostica reveals A murky manger with both starsShining unaltered is a sign of rain While if the northern Ass is dimmedBy vaporous shroud he of the south gleam radiant Expect a south wind the vaporous shroud and radianceExchanging stars harbinger Boreas Allen 1898 The meaning of this verse is that if Asellus Borealis or Gamma Cancris 14 is hidden by clouds the wind will be from the south and that situation will be reversed if Asellus Australis is obscured There is some doubt however as to the accuracy of this as Allen notes Our modern Weather Bureau would probably tell us that if one of these stars were thus concealed the other also would be Allen 1898 But Delta Cancri also acts as more than just a dubious weather guide it is a reliable signpost for finding the vividly red star X Cancri as Patrick Moore notes in his guidebook Stars of the Southern Skies In the same binocular field with Delta Cancri you will find one of the reddest stars in the sky X Cancri It is a semi regular variable at maximum it rises to magnitude 5 and it never falls below 7 3 so that it can always be seen with binoculars It looks rather like a tiny glowing coal Page 146 Moore 1994 Delta Cancri also marks the radiant of the Delta Cancrids meteor shower In 1876 the possibility of Delta Cancri having a companion star was proposed 15 References edit a b c d e van Leeuwen F 2007 Validation of the new Hipparcos reduction Astronomy and Astrophysics 474 2 653 664 arXiv 0708 1752 Bibcode 2007A amp A 474 653V doi 10 1051 0004 6361 20078357 S2CID 18759600 a b c Johnson H L et al 1966 UBVRIJKL photometry of the bright stars Communications of the Lunar and Planetary Laboratory 4 99 99 Bibcode 1966CoLPL 4 99J a b c d e Luck R Earle September 2015 Abundances in the Local Region I G and K Giants The Astronomical Journal 150 3 23 arXiv 1507 01466 Bibcode 2015AJ 150 88L doi 10 1088 0004 6256 150 3 88 S2CID 118505114 88 a b c d e Massarotti Alessandro et al January 2008 Rotational and radial velocities for a sample of 761 HIPPARCOS giants and the role of binarity The Astronomical Journal 135 1 209 231 Bibcode 2008AJ 135 209M doi 10 1088 0004 6256 135 1 209 Soubiran C et al March 2008 Vertical distribution of Galactic disk stars IV AMR and AVR from clump giants Astronomy and Astrophysics 480 1 91 101 arXiv 0712 1370 Bibcode 2008A amp A 480 91S doi 10 1051 0004 6361 20078788 S2CID 16602121 a b Naming Stars IAU org Retrieved 16 December 2017 In the Sky Earth astronomy reference utility showing the ecliptic and relevant date as at J2000 present Hessman F V Dhillon V S Winget D E Schreiber M R Horne K Marsh T R Guenther E Schwope A Heber U 2010 On the naming convention used for multiple star systems and extrasolar planets arXiv 1012 0707 astro ph SR a b c Allen Richard Hinckley Star Names Their Lore and Meaning 1898 IAU Working Group on Star Names WGSN International Astronomical Union retrieved 22 May 2016 WG Triennial Report 2015 2018 Star Names PDF p 5 Retrieved 2018 07 14 陳久金 2005 Zhōngguo Xingzuo Shenhua 中國星座神話 Chinese Constellation Mythology 台灣古籍出版有限公司 p 394 ISBN 978 986 7332 25 7 亮星中英對照表 English Chinese Glossary of Bright Stars Hong Kong Space Museum in Chinese Retrieved February 3 2018 Asellus Australis Kaler 2009 ASELLUS BOREALIS Archived from the original on 2011 07 16 Burnham S W 1878 The companion to delta Cancri The Observatory 2 60 Bibcode 1878Obs 2 60B Books edit Richard H Allen 28 February 2013 Star Names Their Lore and Meaning Courier Corporation ISBN 978 0 486 13766 7 Robert Burnham 15 April 2013 Burnham s Celestial Handbook Volume One An Observer s Guide to the Universe Beyond the Solar System Courier Corporation pp 340 ISBN 978 0 486 31902 5 James B Kaler 20 November 2006 The Cambridge Encyclopedia of Stars Cambridge University Press ISBN 978 0 521 81803 2 Lloyd Motz Carol Nathanson 1 November 1988 The constellations Doubleday ISBN 9780385176002 Patrick Moore 13 October 1998 Atlas of the Universe Cambridge University Press ISBN 978 0 521 64210 1 Patrick Moore 1994 Stars of the Southern Skies Penguin ISBN 978 0 14 024315 4 Retrieved from https en wikipedia org w index php title Delta Cancri amp oldid 1171117506, wikipedia, wiki, book, books, library,
