Hamal: Difference between revisions

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
VisualWikitext
imported>OAbot
m Open access bot: url-access updated in citation with #oabot.
 
imported>Kwékwlos
No edit summary
 
(One intermediate revision by one other user not shown)
Line 15: Line 15:
}}
}}
{{Starbox observe
{{Starbox observe
  | epoch      = [[J2000.0]]
  | epoch      = J2000
| equinox    = [[J2000.0]] ([[International Celestial Reference System|ICRS]])
  | constell    = [[Aries (constellation)|Aries]]
  | constell    = [[Aries (constellation)|Aries]]
  | ra          = {{RA|02|07|10.40570}}<ref name=aaa474_2_653/>
  | ra          = {{RA|02|07|10.40570}}<ref name=aaa474_2_653/>
Line 78: Line 77:


== Planetary system ==
== Planetary system ==
In 2011, the likely presence of a planet in orbit around this star was reported by Byeong-Cheol Lee, et al. It was detected using the [[radial velocity method]], based upon measurements made between 2003 and 2010 at the [[Bohyunsan Optical Astronomy Observatory]] in Korea. The object has an [[orbital period]] of 381&nbsp;days and an [[orbital eccentricity|eccentricity]] of 0.25. The lower bound on this object's mass is about 1.8 times the mass of [[Jupiter]]. The estimated [[semi-major axis]] of the planet's orbit is 1.2&nbsp;[[astronomical unit]]s (AU),<ref name=aaa529_A134/> which would give it a [[periapsis]] distance of 0.9&nbsp;AU and an [[apoapsis]] distance of 1.5&nbsp;AU. By comparison, the star has a radius of 0.07&nbsp;AU.<ref name=orbit_note/>
In 2011, the likely presence of a planet in orbit around this star was reported by Byeong-Cheol Lee, et al. It was detected using the [[radial velocity method]], based upon measurements made between 2003 and 2010 at the [[Bohyunsan Optical Astronomy Observatory]] in [[South Korea]]. The object has an [[orbital period]] of 381&nbsp;days and an [[orbital eccentricity|eccentricity]] of 0.25. The lower bound on this object's mass is about 1.8 times the mass of [[Jupiter]]. The estimated [[semi-major axis]] of the planet's orbit is 1.2&nbsp;[[astronomical unit]]s (AU),<ref name=aaa529_A134/> which would give it a [[periapsis]] distance of 0.9&nbsp;AU and an [[apoapsis]] distance of 1.5&nbsp;AU. By comparison, the star has a radius of 0.07&nbsp;AU.<ref name=orbit_note/>


{{OrbitboxPlanet begin
{{OrbitboxPlanet begin
Line 129: Line 128:
  | volume=166 | issue=6 | pages=268 | date=December 1, 2023
  | volume=166 | issue=6 | pages=268 | date=December 1, 2023
  | doi=10.3847/1538-3881/ad08be | doi-access=free
  | doi=10.3847/1538-3881/ad08be | doi-access=free
  | bibcode=2023AJ....166..268B | issn=0004-6256}}</ref>
  | bibcode=2023AJ....166..268B | issn=0004-6256| arxiv=2505.23514 }}</ref>


<ref name="Bonfanti2015">{{citation | postscript=.
<ref name="Bonfanti2015">{{citation | postscript=.
Line 289: Line 288:
  | isbn=978-1-931559-44-7 }}</ref>
  | isbn=978-1-931559-44-7 }}</ref>


<ref name="WGSN">{{citation | postscript=.
<ref name="WGSN">{{citation
| postscript=.
  | title=IAU Working Group on Star Names (WGSN)
  | title=IAU Working Group on Star Names (WGSN)
  | publisher=International Astronomical Union
  | publisher=International Astronomical Union
  | url=https://www.iau.org/science/scientific_bodies/working_groups/280/
  | url=https://www.iau.org/science/scientific_bodies/working_groups/280/
  | access-date=22 May 2016}}</ref>
  | access-date=22 May 2016
| archive-date=30 March 2019
| archive-url=https://web.archive.org/web/20190330194042/https://www.iau.org/science/scientific_bodies/working_groups/280/
| url-status=dead
}}</ref>


<ref name="WGSN1">{{citation | postscript=.
<ref name="WGSN1">{{citation | postscript=.
Line 341: Line 345:
[[Category:Hipparcos objects|009884]]
[[Category:Hipparcos objects|009884]]
[[Category:Stars with proper names]]
[[Category:Stars with proper names]]
[[Category:Lucidae]]

Latest revision as of 12:34, 30 October 2025

Template:Short description Script error: No such module "about".

Hamal
Template:Location mark
Location of α Arietis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Aries
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 2.00[2]
Characteristics
Evolutionary stage Red giant branch
Spectral type K1IIIb
U−B Template:Engvar +1.13[2]
B−V Template:Engvar +1.15[2]
V−R Template:Engvar +0.7[3]
R−I Template:Engvar +0.62[4]
Variable type Suspected[5]
Astrometry
Radial velocity (Rv)−14.2±0.9[6] km/s
Proper motion (μ) RA: +188.55 mas/yr[1]
Dec.: −148.08 mas/yr[1]
Parallax (π)49.56±0.25 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)+0.47±0.04[7]
Details
MassTemplate:Val[8] Template:Solar mass
RadiusTemplate:Val[9] Template:Solar radius
LuminosityTemplate:Val[9] Template:Solar luminosity
Surface gravity (log g)2.3[10] cgs
TemperatureTemplate:Val[8] K
Metallicity [Fe/H]−0.214[10] dex
Rotational velocity (v sin i)3.44[8] km/s
Age3.4±1.9[11] Gyr
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Template:Odlist[3][4]
Database references
SIMBADdata

Script error: No such module "Check for unknown parameters".

Hamal, pronounced Template:IPAc-en,[12] is a star in the northern zodiacal constellation of Aries.[4][13] It has the Bayer designation Alpha Arietis, which is Latinized from α Arietis and abbreviated Alpha Ari or α Ari. This star is visible to the naked eye with an apparent visual magnitude of 2.0.[2] Hamal is the brightest star in the constellation and, on average, the 50th-brightest star in the night sky. Based upon parallax measurements made with the Hipparcos astrometry satellite,[14][15] Hamal is about Template:Convert from Earth.[1] It is drifting closer to the Sun with a radial velocity of −14 km/s.[6]

This is an aging giant star that may host an orbiting planet with a mass greater than Jupiter.[8]

Nomenclature

File:AriesCC.jpg
Hamal is the brightest star in the constellation of Aries.

Alpha Arietis is the star's Bayer designation. It also bears the Flamsteed designation of 13 Arietis.

The traditional name Hamal (also written Hemal, Hamul, Ras Hammel) derives from the Arabic Script error: No such module "Lang". rās al-ħamal "head of the ram", in turn from the name for the constellation as a whole, Al Ħamal "the ram".[16] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[17] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[18] included a table of the first two batches of names approved by the WGSN; which included Hamal for this star.[19]

In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning Bond (asterism), refers to an asterism consisting of Hamal, β Arietis and γ Arietis.[20] Consequently, the Chinese name for Hamal itself is Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx).[21]

Properties

The spectrum of this star matches a stellar classification of K2 III Ca-1, with the luminosity class of III indicating that it is an evolved giant star that has exhausted the supply of hydrogen at its core and is now on the red-giant branch.[22] The 'Ca-1' portion of the classification indicates that it shows weaker than normal lines of calcium in its spectrum. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.[23] It is estimated to have 65% more mass than the Sun,[10] while interferometric measurements using the Navy Precision Optical Interferometer show it to be 15 times larger in diameter.[9] Despite its enlarged girth, this star is still spinning with a slightly faster equatorial azimuthal velocity than the Sun, having a projected rotational velocity of 3.44 km s−1.[8]

Hamal is radiating about 91[24] times the Sun's luminosity from its outer envelope at an effective temperature of Template:Val.[10] This is cooler than the surface of the Sun, giving it the orange-hued glow of a K-type star. It is suspected to be slightly variable, with an amplitude of 0.06 magnitude.[5] The abundance of elements other than hydrogen and helium, what astronomers term the star's metallicity, is only around 60% that in the Sun.[24]Template:Efn The star displays low amplitude pulsations with periods of 0.571 and 0.190 days.[25]

Planetary system

In 2011, the likely presence of a planet in orbit around this star was reported by Byeong-Cheol Lee, et al. It was detected using the radial velocity method, based upon measurements made between 2003 and 2010 at the Bohyunsan Optical Astronomy Observatory in South Korea. The object has an orbital period of 381 days and an eccentricity of 0.25. The lower bound on this object's mass is about 1.8 times the mass of Jupiter. The estimated semi-major axis of the planet's orbit is 1.2 astronomical units (AU),[8] which would give it a periapsis distance of 0.9 AU and an apoapsis distance of 1.5 AU. By comparison, the star has a radius of 0.07 AU.[26]

Template:OrbitboxPlanet begin Template:OrbitboxPlanet Template:Orbitbox end

In culture

Hamal's orientation with relation to the Earth's orbit around the Sun gives it a certain importance not apparent from its modest brightness. Between 2000 and 100 BCE, the apparent path of the Sun through the Earth's sky placed it in Aries at the northern vernal equinox, the point in time marking the start of spring in the Northern Hemisphere.[27] This is why most astrology columns in modern newspapers begin with Aries.[28] While the vernal equinox has moved to Pisces since then due to precession of the equinoxes,[27] Hamal has remained in mind as a bright star near what was apparently an important place when people first studied the night sky.[13] Currently (epoch J2000) its declination is almost exactly equal to the latitude of the Tropic of Cancer, meaning it can be used to find the position of that imaginary line when the Sun is not nearby.

The other name of Hamal, Hamul, was used for the name of a U.S. Navy ship, Template:USS.

In 1953, fictional planet orbiting Alpha Arietis, named Lithia, appeared in A Case of Conscience, a classic science fiction novel by James Blish. The planet serves as the arena of the major part of the story, being a homeworld to a fictional sentient race, being studied by humans. Real-life equivalent of Lithia was unknown at the time of the novel's creation.

Notes

Template:Notelist

References

Template:Reflist

External links

Template:Sky

Template:Stars of Aries

Template:Authority control

  1. ↑ a b c d e Cite error: Invalid <ref> tag; no text was provided for refs named aaa474_2_653
  2. ↑ a b c d Cite error: Invalid <ref> tag; no text was provided for refs named clpl4_99
  3. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named sb0
  4. ↑ a b c Cite error: Invalid <ref> tag; no text was provided for refs named bsc2
  5. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named nsv1
  6. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named rgcrv
  7. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named aj135_3_892
  8. ↑ a b c d e f Cite error: Invalid <ref> tag; no text was provided for refs named aaa529_A134
  9. ↑ a b c Cite error: Invalid <ref> tag; no text was provided for refs named npoi
  10. ↑ a b c d Cite error: Invalid <ref> tag; no text was provided for refs named gray2019
  11. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Bonfanti2015
  12. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Kunitzsch
  13. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named kaler
  14. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named aaa323_L49
  15. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named GSM
  16. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named allen1899
  17. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named WGSN
  18. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named WGSN1
  19. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named IAU-CSN
  20. ↑ 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.
  21. ↑ Template:In lang 香港太空館 - 研究資源 - 亮星中英對照表 Template:Webarchive, Hong Kong Space Museum. Accessed on line November 23, 2010.
  22. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named mnras340_3_763
  23. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named baas25_1319
  24. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named aaa526_A100
  25. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Kim_et_al_2006
  26. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named orbit_note
  27. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named ecs
  28. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named raymo1982
Retrieved from "http://debianws.lexgopc.com/wiki143/index.php?title=Hamal&oldid=3240367"