Observation data Epoch J2000.0 Equinox J2000.0 ( ICRS) | |
---|---|
Constellation | Hydra |
Right ascension | 09h 39m 51.36145s [1] |
Declination | −01° 08′ 34.1135″ [1] |
Apparent magnitude (V) | 3.91 [2] |
Characteristics | |
Spectral type | K2.5 III [2] |
B−V color index | 1.32 |
Variable type | Suspected [3] |
Astrometry | |
Radial velocity (Rv) | +24.19±0.36 [4] km/s |
Proper motion (μ) |
RA: +46.96
[1]
mas/
yr Dec.: −62.39 [1] mas/ yr |
Parallax (π) | 12.39 ± 0.14 mas [1] |
Distance | 263 ± 3
ly (80.7 ± 0.9 pc) |
Absolute magnitude (MV) | −0.63 [5] |
Details | |
Mass | 1.92 [2] M☉ |
Radius | 33 [4] R☉ |
Luminosity | 83 [2] L☉ |
Surface gravity (log g) | 2.2 [4] cgs |
Temperature | 4,244±32 [2] K |
Metallicity [Fe/H] | −0.05 [2] dex |
Rotational velocity (v sin i) | 4.5 [4] km/s |
Age | 2.47 [2] Gyr |
Other designations | |
Database references | |
SIMBAD | data |
Iota Hydrae (ι Hydrae, abbreviated Iota Hya, ι Hya), formally named Ukdah /ˈʌkdə/, [7] is a star in the constellation of Hydra, about 8° to the north-northwest of Alphard (Alpha Hydrae) [8] and just to the south of the celestial equator. [9] Visible to the naked eye, it is a suspected variable star with an apparent visual magnitude that ranges between 3.87 and 3.91. [3] Based upon an annual parallax shift of 12.39 mas measured during the Hipparcos mission, [1] it is located around 263 light-years from the Sun.
ι Hydrae ( Latinised to Iota Hydrae) is the star's Bayer designation.
This star along with Tau¹ Hydrae, Tau² Hydrae and 33 Hydrae (A Hydrae), were Ptolemy's Καμπή (Kampē); but Kazwini knew them as عقدة ʽuqdah (or ʽuḳdah) "knot". [10] According to a 1971 NASA memorandum, [11] Ukdah was the name of an asterism of four stars: Tau¹ Hydrae as Uḳdah I, Tau² Hydrae as Uḳdah II, 33 Hydrae as Uḳdah III and Iota Hydrae as Uḳdah IV. In 2016, the IAU organized a Working Group on Star Names (WGSN) [12] to catalog and standardize proper names for stars. The WGSN approved the name Ukdah for Iota Hydrae on 1 June 2018 and it is now so included in the List of IAU-approved Star Names. [7]
In Chinese, 星宿 (Xīng Sù), meaning Star or asterism, refers to an asterism consisting of ι Hydrae, Alphard, τ1 Hydrae, τ2 Hydrae, 26 Hydrae, 27 Hydrae, HD 82477 and HD 82428. [13] Consequently, ι Hydrae are known as 星宿四 (Xīng Sù sì, English: the Fourth Star of Star). [14]
This is an evolved K-type giant star with a stellar classification of K2.5 III. [2] It is a Barium star, which means that, for a giant star, it displays unusually strong absorption lines of singly-ionized barium and strontium. [15] Iota Hydrae has nearly twice [2] the mass of the Sun and has expanded to 33 times the Sun's radius. [4] It is around 2.5 billion years old and is spinning with a leisurely projected rotational velocity of 4.5 [4] km/s. It may be a member of the Wolf 630 moving group of stars that share a common trajectory through space. [16]
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Observation data Epoch J2000.0 Equinox J2000.0 ( ICRS) | |
---|---|
Constellation | Hydra |
Right ascension | 09h 39m 51.36145s [1] |
Declination | −01° 08′ 34.1135″ [1] |
Apparent magnitude (V) | 3.91 [2] |
Characteristics | |
Spectral type | K2.5 III [2] |
B−V color index | 1.32 |
Variable type | Suspected [3] |
Astrometry | |
Radial velocity (Rv) | +24.19±0.36 [4] km/s |
Proper motion (μ) |
RA: +46.96
[1]
mas/
yr Dec.: −62.39 [1] mas/ yr |
Parallax (π) | 12.39 ± 0.14 mas [1] |
Distance | 263 ± 3
ly (80.7 ± 0.9 pc) |
Absolute magnitude (MV) | −0.63 [5] |
Details | |
Mass | 1.92 [2] M☉ |
Radius | 33 [4] R☉ |
Luminosity | 83 [2] L☉ |
Surface gravity (log g) | 2.2 [4] cgs |
Temperature | 4,244±32 [2] K |
Metallicity [Fe/H] | −0.05 [2] dex |
Rotational velocity (v sin i) | 4.5 [4] km/s |
Age | 2.47 [2] Gyr |
Other designations | |
Database references | |
SIMBAD | data |
Iota Hydrae (ι Hydrae, abbreviated Iota Hya, ι Hya), formally named Ukdah /ˈʌkdə/, [7] is a star in the constellation of Hydra, about 8° to the north-northwest of Alphard (Alpha Hydrae) [8] and just to the south of the celestial equator. [9] Visible to the naked eye, it is a suspected variable star with an apparent visual magnitude that ranges between 3.87 and 3.91. [3] Based upon an annual parallax shift of 12.39 mas measured during the Hipparcos mission, [1] it is located around 263 light-years from the Sun.
ι Hydrae ( Latinised to Iota Hydrae) is the star's Bayer designation.
This star along with Tau¹ Hydrae, Tau² Hydrae and 33 Hydrae (A Hydrae), were Ptolemy's Καμπή (Kampē); but Kazwini knew them as عقدة ʽuqdah (or ʽuḳdah) "knot". [10] According to a 1971 NASA memorandum, [11] Ukdah was the name of an asterism of four stars: Tau¹ Hydrae as Uḳdah I, Tau² Hydrae as Uḳdah II, 33 Hydrae as Uḳdah III and Iota Hydrae as Uḳdah IV. In 2016, the IAU organized a Working Group on Star Names (WGSN) [12] to catalog and standardize proper names for stars. The WGSN approved the name Ukdah for Iota Hydrae on 1 June 2018 and it is now so included in the List of IAU-approved Star Names. [7]
In Chinese, 星宿 (Xīng Sù), meaning Star or asterism, refers to an asterism consisting of ι Hydrae, Alphard, τ1 Hydrae, τ2 Hydrae, 26 Hydrae, 27 Hydrae, HD 82477 and HD 82428. [13] Consequently, ι Hydrae are known as 星宿四 (Xīng Sù sì, English: the Fourth Star of Star). [14]
This is an evolved K-type giant star with a stellar classification of K2.5 III. [2] It is a Barium star, which means that, for a giant star, it displays unusually strong absorption lines of singly-ionized barium and strontium. [15] Iota Hydrae has nearly twice [2] the mass of the Sun and has expanded to 33 times the Sun's radius. [4] It is around 2.5 billion years old and is spinning with a leisurely projected rotational velocity of 4.5 [4] km/s. It may be a member of the Wolf 630 moving group of stars that share a common trajectory through space. [16]
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cite web}}
: CS1 maint: postscript (
link)