| dbo:abstract |
U Hydrae is a single star in the equatorial constellation of Hydra, near the northern constellation border with Sextans. It is a semiregular variable star of sub-type SRb, with its brightness ranging from visual magnitude (V) 4.7 to 5.2 over a 450-day period, with some irregularity. This object is located at a distance of approximately 680 light years from the Sun based on parallax. It is drifting closer with a radial velocity of −26 km/s. This is a carbon-rich red giant star on the asymptotic giant branch – a carbon star – with s-process elements appearing in the spectrum. It has a stellar classification of C-N5 with a carbon star class of C2 5-. The star is losing mass at the rate of 1.2×10−7 M☉·yr−1, with an outflow velocity of 6.9 km/s. Technetium has been detected in the spectrum, suggesting the star has experienced a third dredge-up episode due to thermal pulses of the helium-burning shell some time within the last 100,000 years. An ultraviolet (UV) excess has been detected coming from an extended elliptical ring that surrounds this star. It has a mean angular radius of 110″ and lines up with a detached shell of dusty material that was previously detected in the infrared band. The material was most likely ejected from the star due to mass loss episodes. The probable cause of the UV emission is from the movement of the star through space and possibly shock-excited molecules of H2. The emission does not show a bow-shock-like structure. (en) うみへび座U星 (U Hydrae) はうみへび座の5等星。そのスペクトルから炭素星に分類され、際立って赤く見える。 (ja) U Hydrae är en halvregelbunden variabel av SRB-typ i stjärnbilden Vattenormen. Stjärnan varierar mellan visuell magnitud +4,56 och 5,4 med en period av 389,4 dygn. (sv) 長蛇座U，又名BD-12 3218，HD 92055、SAO 156110、HR 4163，是長蛇座的一颗恒星，视星等为4.82，位于銀經259.97，銀緯38.07，其B1900.0坐标为赤經10h 32m 36.9s，赤緯-12° 38.07′ 52″。 (zh) |
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wiki-commons:Special:FilePath/UHyaLightCurve.png?width=300 |
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dbr:Stellar_mass_loss dbr:Angular_radius dbr:All_Sky_Automated_Survey dbr:Hydra_(constellation) dbr:Infrared_astronomy dbr:Stellar_classification dbr:Light_curve dbc:Asymptotic-giant-branch_stars dbc:Bright_Star_Catalogue_objects dbc:Durchmusterung_objects dbc:Henry_Draper_Catalogue_objects dbc:Hipparcos_objects dbc:Hydra_(constellation) dbc:Objects_with_variable_star_designations dbc:Semiregular_variable_stars dbr:Constellation dbr:S-process dbr:Light_year dbr:Star dbr:Stellar_spectrum dbr:Stellar_parallax dbr:Dredge-up dbr:Carbon_star dbr:Celestial_equator dbr:Asymptotic_giant_branch dbr:Sun dbr:Semiregular_variable_star dbr:Technetium_star dbc:Carbon_stars dbr:Radial_velocity dbr:Sextans dbr:Helium_fusion dbr:Shock_(mechanics) dbr:Ultraviolet_astronomy dbr:Photometric_system dbr:Red_giant_star dbr:File:UHyaLightCurve.png |
| dbp:absmagV |
−1.70 (en) |
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4.890000 (xsd:double) |
| dbp:class |
(en) C-N5 C2 5- (en) |
| dbp:constell |
dbr:Hydra_(constellation) |
| dbp:epoch |
J2000 (en) |
| dbp:luminosity |
3476 (xsd:integer) |
| dbp:mass |
0.750000 (xsd:double) |
| dbp:metalFe |
−0.1 (en) |
| dbp:pError |
0.230000 (xsd:double) |
| dbp:parallax |
4.800000 (xsd:double) |
| dbp:propMoDec |
−37.72 (en) |
| dbp:propMoRa |
+42.59 (en) |
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dbr:Asymptotic_giant_branch |
| dbp:variable |
dbr:Semiregular_variable_star |
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| dcterms:subject |
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dbr:Star |
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| rdfs:comment |
うみへび座U星 (U Hydrae) はうみへび座の5等星。そのスペクトルから炭素星に分類され、際立って赤く見える。 (ja) U Hydrae är en halvregelbunden variabel av SRB-typ i stjärnbilden Vattenormen. Stjärnan varierar mellan visuell magnitud +4,56 och 5,4 med en period av 389,4 dygn. (sv) 長蛇座U，又名BD-12 3218，HD 92055、SAO 156110、HR 4163，是長蛇座的一颗恒星，视星等为4.82，位于銀經259.97，銀緯38.07，其B1900.0坐标为赤經10h 32m 36.9s，赤緯-12° 38.07′ 52″。 (zh) U Hydrae is a single star in the equatorial constellation of Hydra, near the northern constellation border with Sextans. It is a semiregular variable star of sub-type SRb, with its brightness ranging from visual magnitude (V) 4.7 to 5.2 over a 450-day period, with some irregularity. This object is located at a distance of approximately 680 light years from the Sun based on parallax. It is drifting closer with a radial velocity of −26 km/s. (en) |
| rdfs:label |
うみへび座U星 (ja) U Hydrae (en) U Hydrae (sv) 長蛇座U (zh) |
| owl:sameAs |
freebase:U Hydrae wikidata:U Hydrae dbpedia-ja:U Hydrae dbpedia-sk:U Hydrae dbpedia-sv:U Hydrae dbpedia-zh:U Hydrae https://global.dbpedia.org/id/4iQgT yago-res:U Hydrae |
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wikipedia-en:U_Hydrae?oldid=1079516396&ns=0 |
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wiki-commons:Special:FilePath/UHyaLightCurve.png |
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wikipedia-en:U_Hydrae |
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dbr:Hydra_(constellation) dbr:List_of_semiregular_variable_stars dbr:List_of_stars_in_Hydra dbr:List_of_variable_stars |
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wikipedia-en:U_Hydrae |
