Delta Hydrae

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Template:Short description

Delta Hydrae
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Hydra
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 4.146[2]
Characteristics
δ Hydrae Aa
Spectral type A1 Vnn[3]
U−B Template:Engvar +0.003[2]
B−V Template:Engvar +0.008[2]
Astrometry
Radial velocity (Rv)4.10[4] km/s
Proper motion (μ) RA: −70.19[1] mas/yr
Dec.: −7.90[1] mas/yr
Parallax (π)20.34±0.63 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)+0.68[5]
Position (relative to δ Hydrae A)
Componentδ Hydrae B
Angular distanceScript error: No such module "val".[6]″
Position angleScript error: No such module "val".[6]°
Projected separation147[7] AU
Orbit[7]
PrimaryAa
CompanionAb
Period (P)~200 days
Semi-major axis (a)0.9 AU
Details[7]
δ Hydrae Aa
Mass2.43 Template:Solar mass
Radius3.1 Template:Solar radius
Luminosity42.7[8] Template:Solar luminosity
Temperature8,995 K
Rotational velocity (v sin i)285[3] km/s
Age500 Myr
δ Hydrae Ab
Mass0.58 Template:Solar mass
Radius0.54 Template:Solar radius
Temperature3,973 K
Metallicity [Fe/H]{{{metal_fe2}}} dex
Age500 Myr
δ Hydrae B
Mass0.44 Template:Solar mass
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
δ Hya, 4 Hydrae, BD+06°2001, FK5 1223, HD 73262, HIP 42313, HR 3410, SAO 116965[9]
Database references
SIMBADdata

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Delta Hydrae, Latinized from δ Hydrae, is a triple star in the equatorial constellation of Hydra. It is visible to the naked eye with an apparent visual magnitude of 4.146.[2] Based upon an annual parallax shift of 20.34 mas, it is located about 160 light years distant.

Characteristics

This is a hierarchical triple system. δ Hydrae Aa and δ Hydrae Ab form a close binary system with an orbital separation of 0.9 astronomical units, taking about 200 days to complete an orbit.[7] The outer companion, δ Hydrae B, has an angular separation of Script error: No such module "val". from the Aa–Ab pair, along a position angle of Script error: No such module "val"., as of 2003.[6] At the system's distance, this separation translates in a physical projected separation of 147 AU.[7]

The brighter component, δ Hydrae Aa, is an A-type main sequence star with a stellar classification of A1 Vnn.[3] It is spinning rapidly with a projected rotational velocity of 285 km/s. This is giving the star an oblate shape with an equatorial bulge that is 20% larger than the polar radius.[3] It has an estimated 2.43 times the mass of the Sun and 3.1 times the Sun's radius.[7] The star radiates 42.7 times the solar luminosity from its photosphere[8] at an effective temperature of 8,995 K.[7]

Its inner companion, δ Hydrae Ab, is a red dwarf star, with 0.58 times the mass, 0.54 times the Sun's radius, and an effective temperature of 3,973 K. It may form a common envelope system when the primary evolve into a red giant.[7]

The outer companion has a visual magnitude of 11.15.[10] X-ray emissions have been detected from this location in space, which may be coming from a companion star.[6]

Name and etymology

In the catalogue of stars in the Calendarium of Al Achsasi Al Mouakket, this star was designated Lisan al Shudja, which was translated into Latin as Lingua Hydri, meaning the snake's tongue.[11] This star, along with ε Hya, ζ Hya, η Hya, ρ Hya and σ Hya (Minchir), were Ulugh Beg's Min al Azʽal, "Belonging to the Uninhabited Spot".[12]

According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Min al Azʽal or Minazal were the title for five stars :δ Hya as Minazal I, η Hya as Minazal II, ε Hya as Minazal III, ρ Hya as Minazal IV and ζ Hya as Minazal V (exclude σ Hya)[13]

In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning Willow (asterism), refers to an asterism consisting of δ Hydrae, σ Hydrae, η Hydrae, ρ Hydrae, ε Hydrae, ζ Hydrae, ω Hydrae and θ Hydrae[14] Consequently, δ Hydrae itself is known as Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx.)[15]

The people of Groote Eylandt called Unwala, "The Crab", for the star cluster including this star, ε Hya, ζ Hya, η Hya, ρ Hya and σ Hya (Minchir).[16]

See also

References

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  1. ↑ a b c d e Script error: No such module "citation/CS1".
  2. ↑ a b c d Script error: No such module "citation/CS1".
  3. ↑ a b c d Script error: No such module "citation/CS1".
  4. ↑ Script error: No such module "citation/CS1".
  5. ↑ Script error: No such module "citation/CS1".
  6. ↑ a b c d Script error: No such module "citation/CS1".
  7. ↑ a b c d e f g h Script error: No such module "citation/CS1".
  8. ↑ a b Script error: No such module "citation/CS1".
  9. ↑ Template:Cite simbad
  10. ↑ Script error: No such module "citation/CS1".
  11. ↑ Script error: No such module "citation/CS1".
  12. ↑ Script error: No such module "citation/CS1".
  13. ↑ Jack W. Rhoads - Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars, Jet Propulsion Laboratory, California Institute of Technology; November 15, 1971
  14. ↑ Template:In lang 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, Template:ISBN.
  15. ↑ Template:In lang AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 28 日 Template:Webarchive
  16. ↑ Helaine Selin, ed., Encyclopaedia of the history of science, technology, and medicine in non-western cultures, Dordrecht, Kluwer Academic Publishers, 1997, p.105.

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External links

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Template:Stars of Hydra

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