Iota Orionis

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Template:Short description

ι Orionis
Template:Location mark
Location of ι Ori (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Orion
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 2.77[2]
Characteristics
ι Orionis A
Spectral type O9 III + B0.8 III/IV[3] + B2:IV:[4]
U−B Template:Engvar −1.08[2]
B−V Template:Engvar −0.24[2]
ι Orionis B
Spectral type B8 III[5]
Variable type Orion[6]
Astrometry
ι Orionis A
Radial velocity (Rv)21.5[7] km/s
Proper motion (μ) RA: +1.42[1] mas/yr
Dec.: −0.46[1] mas/yr
Parallax (π)1.40±0.22 mas[1]
DistanceTemplate:Val[4] pc
ι Orionis B
Radial velocity (Rv)21.5[7] km/s
Proper motion (μ) RA: +1.42[8] mas/yr
Dec.: −0.46[8] mas/yr
Parallax (π)2.787±0.0476 mas[8]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Orbit[3][9]
Primaryι Orionis Aa1
Companionι Orionis Aa2
Period (P)29.1338 days
Semi-major axis (a)Template:Solar radius
Eccentricity (e)0.764
Inclination (i)~60°
Periastron epoch (T)2,450,072.80 HJD
Details
ι Ori Aa1
Mass23.1[9] Template:Solar mass
Radius8.3[9] Template:Solar radius
Luminosity68,000[9] Template:Solar luminosity
Surface gravity (log g)3.73[3] cgs
Temperature32,500[3] K
Metallicity [Fe/H]+0.10[10] dex
Rotational velocity (v sin i)122[11] km/s
Age4.0–5.5[3] Myr
ι Ori Aa2
Mass13.1[9] Template:Solar mass
Radius5.4[9] Template:Solar radius
Luminosity8,630[9] Template:Solar luminosity
Surface gravity (log g)3.78[3] cgs
Temperature27,000[3] K
Metallicity [Fe/H]{{{metal_fe2}}} dex
AgeTemplate:Val[3] Myr
ι Ori B
Mass5.12[12] Template:Solar mass
Surface gravity (log g)4.0[10] cgs
Temperature18,000[10] K
Age~3[10] Myr
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Hatysa, ι Orionis, Na'ir al Saif, BD−06°1241, FK5 209, SAO 132323, ADS 4193, WDS J05354-0555
ι Ori A: 44 Orionis, HD 37043, HIP 26241, HR 1899, 2MASS J05352597-0554357
ι Ori B: V2451 Ori, 2MASS J05352645-0554445
ι Ori C: 2MASS J05352920-0554471
Database references
SIMBADι Ori
ι Ori B
ι Ori C

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Iota Orionis (ι Orionis, abbreviated ι Ori) is a multiple star system in the equatorial constellation of Orion the hunter. It is the eighth-brightest member of Orion with an apparent visual magnitude of 2.77 and also the brightest member of the asterism known as Orion's Sword. It is a member of the NGC 1980 open cluster. From parallax measurements, it is located at a distance of roughly Template:Convert from the Sun.

The system has three visible components designated Iota Orionis A, B and C. Iota Orionis A has also been resolved using speckle interferometry and is also a massive spectroscopic binary, with components Iota Orionis Aa1 (officially named Hatysa Template:IPAc-en), Aa2, and Ab.

Nomenclature

ι Orionis (Latinised to Iota Orionis) is the system's Bayer designation. The designations of the three constituents as Iota Orionis A, B and C, and those of A's components - Iota Orionis Aa1, Aa2, 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).[13]

The system has the traditional name Nair al Saif, from the Arabic نير السيف nayyir as-sayf "the Bright One of the Sword", though this is little used.[14][15][16] Since Antonín Bečvář's 1951 Atlas Coeli, it has borne the proper name Hatysa. Kunitzsch was unable to find an older source for the latter name.[17]

In 2016, the IAU organized a Working Group on Star Names (WGSN)[18] to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[19] It approved the name Hatysa for the component Iota Orionis Aa on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.[20]

Iota Orionis B is a variable star and in 2011 it was given the variable star designation V2451 Orionis.[6]

Distance

File:The Orion Nebula M42.jpg
ι Orionis is the bright star to the right (south) of the Orion Nebula

Iota Orionis has a parallax of Template:Val in the Hipparcos new reduction,[1] indicating a distance around Template:Val. The previous published Hipparcos parallax was Template:Val, suggesting a closer distance.[21] Gaia Data Release 3 has individual parallaxes for the two fainter components of the Iota Orionis star system of Template:Val and Template:Val,[8][22] indicating distances of Template:Val and Template:Val respectively, with margins of error of just a few parsecs. There is little doubt that all three stars are at the same distance.[3][9]

Iota Orionis is generally assumed to be associated with the open cluster NGC 1980, which is at a distance of around Template:Val. However, they may not lie at exactly the same distance and Iota Orionis may have a complex history involving stellar encounters and runaway stars.[23] NGC 1980 contains few bright stars other than Iota Orionis. Only eighteen other stars are considered members in a survey down to 14th magnitude, most of them around 9th magnitude but including the 5th magnitude stars HR 1886 and 1887.[24]

Properties

Iota Orionis is dominated by the multiple star Iota Orionis A. It is clearly identified as a double-lined spectroscopic binary whose components are a stellar class O9 III star (blue giant) and a class B0.8 III/IV star about 2 magnitudes fainter.[3] The combined spectral type has long been accepted as O9 III and it was listed as a standard star for that type.[25] The collision of the stellar winds from this pair makes the system a strong X-ray source. Oddly, the two objects of this system appear to have different ages, with the secondary being about double the age of the primary. In combination with the high eccentricity (e=0.764) of their 29-day orbit, this suggests that the binary system was created through a capture, rather than by being formed together and undergoing a mass transfer. This capture may have occurred, for example, through an encounter between two binary systems, with one star being donated from each binary and two runaway stars being ejected.[3][26] A third component Template:Val away has been identified using speckle interferometry and is probably a B2 subgiant.[4][12]

The primary component of Iota Orionis A is a class O giant star with a mass of about Template:Solar mass. It has a surface temperature of Template:Val and radius of Template:Solar radius, resulting in a bolometric luminosity of Template:Solar luminosity. It is calculated to be around nine million years old. The secondary star of the spectroscopic binary pair is a class B giant or subgiant with a mass of about Template:Solar mass. It has a temperature of Template:Val and radius of Template:Solar radius, resulting in it radiating over 8,000 times as much energy as the sun.

Iota Orionis B is a B8 giant at 11" (approximately 5,000 AU[10]) which has been shown to be variable, and likely to be a young stellar object.[5] It is also a helium-weak chemically peculiar star.[27] The fainter Iota Orionis C is an A0 star at 49".[28]

References

Template:Reflist

External links

Template:Stars of Orion

  1. ↑ a b c d e f Cite error: Invalid <ref> tag; no text was provided for refs named aaa474_2_653
  2. ↑ a b c Cite error: Invalid <ref> tag; no text was provided for refs named aass34_1
  3. ↑ a b c d e f g h i j k Cite error: Invalid <ref> tag; no text was provided for refs named apj554_1_362
  4. ↑ a b c Cite error: Invalid <ref> tag; no text was provided for refs named m-a2020
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  7. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named rgcrv
  8. ↑ a b c d Cite error: Invalid <ref> tag; no text was provided for refs named dr3b
  9. ↑ a b c d e f g h Cite error: Invalid <ref> tag; no text was provided for refs named marchenko
  10. ↑ a b c d e Cite error: Invalid <ref> tag; no text was provided for refs named conti
  11. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named ciako
  12. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named msc
  13. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named planetnaming
  14. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named allen1899
  15. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named VizieRn
  16. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named bakich1995b
  17. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named kunitzsch
  18. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named WGSN
  19. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named TriRpt18
  20. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named IAU-LSN
  21. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named perryman
  22. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named dr3c
  23. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named kounkel
  24. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named kharchenko
  25. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named morgan
  26. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named hoogerwerf
  27. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named renson
  28. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named parenago
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