Alcyone (star)

{{Starbox image

| image =

{{Location mark

| image = Pleiades large.jpg | width = 280

| alt = Image of the Pleiades star cluster | float = center

| mark = Red circle.svg | mark_width = 40

| x = 395 | y = 395

}}

| caption = Alcyone in the Pleiades cluster (circled)

}}

{{Starbox observe

| epoch = J2000

| ra = {{RA|03|47|29.077}}

| dec = {{DEC|+24|06|18.49}}

| appmag_v = 2.87{{cite journal|bibcode=2002yCat.2237....0D|title=VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system|journal=CDS/ADC Collection of Electronic Catalogues|volume=2237|last1=Ducati|first1=J. R.|year=2002}}

|constell=Taurus}}

{{Starbox character

| class = B7IIIe{{cite journal |bibcode=1992A&AS...95..535J |title=A southern be star survey : Spectra and envelope radii |last1=Jaschek |first1=C. |last2=Jaschek |first2=M. |journal=Astronomy and Astrophysics Supplement Series |date=1992 |volume=95 |page=535 }}

| b-v = −0.09

| u-b = −0.34

| variable =

}}

{{Starbox astrometry

| radial_v = 5.40{{cite journal|bibcode=2006AstL...32..759G|title=Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system|journal=Astronomy Letters|volume=32|issue=11|pages=759–771|last1=Gontcharov|first1=G. A.|year=2006|doi=10.1134/S1063773706110065|arxiv = 1606.08053 |s2cid=119231169}}

| prop_mo_ra = {{val|19.34|0.39}}

| prop_mo_dec = {{val|-43.67|0.33}}

| parallax = 8.09

| p_error = 0.42

| parallax_footnote =

| dist_pc = 136{{Cite journal

|display-authors= 4

|first1= Carl |last1= Melis

|first2= Mark J. |last2= Reid

|first3= Amy J. |last3= Mioduszewski

|first4= John R. |last4= Stauffer

|first5= Geoffrey |last5= Bower

|date= 29 August 2014

|title= A VLBI resolution of the Pleiades distance controversy

|journal= Science

|volume= 345 |issue= 6200 |pages= 1029–1032

|doi= 10.1126/science.1256101

|pmid= 25170147

|arxiv = 1408.6544 |bibcode = 2014Sci...345.1029M |s2cid= 34750246 }}

| absmag_v = −2.62{{cite journal|doi=10.1007/s10509-006-9173-1|bibcode = 2006Ap&SS.306..113Z |title = Absolute Magnitudes of Be Stars Based on Hipparcos Parallaxes |journal = Astrophysics and Space Science |volume = 306 |issue = 3 |pages = 113 |year = 2006 |last1 = Zhang |first1 = P. |last2 = Liu |first2 = C. Q. |last3 = Chen |first3 = P. S. |s2cid = 122897957 }}

}}

{{Starbox detail

| mass = 5.9{{snd}}6.1{{cite journal|bibcode=2005A&A...441..235Z|title=On the evolutionary status of Be stars. I. Field Be stars near the Sun|journal=Astronomy and Astrophysics|volume=441|pages=235–248|last1=Zorec|first1=J.|last2=Frémat|first2=Y.|last3=Cidale|first3=L.|year=2005|issue=1|doi=10.1051/0004-6361:20053051|arxiv = astro-ph/0509119 |s2cid=17592657}}

| radius = {{val|9.3|0.7}}

| luminosity = 2,030{{cite book|bibcode=2000ASPC..214...13H|chapter=Physical Properties and Evolutionary Stage of Be Stars|title=The Be Phenomenon in Early-Type Stars|volume=214|pages=13|last1=Harmanec|first1=P.|series=ASP Conference Proceedings |editor1=Myron A. Smith |editor2=Huib F. Henrichs |publisher=Astronomical Society of the Pacific |isbn=1-58381-045-5 |journal=|year=2000}}

| temperature = 12,258{{cite journal|bibcode=2013ApJ...768..128T|arxiv=1302.6135|title=A CHARA Array Survey of Circumstellar Disks around Nearby Be-type Stars|journal=The Astrophysical Journal|volume=768|issue=2|pages=128|last1=Touhami|first1=Y.|last2=Gies|first2=D. R.|last3=Schaefer|first3=G. H.|last4=McAlister|first4=H. A.|last5=Ridgway|first5=S. T.|last6=Richardson|first6=N. D.|last7=Matson|first7=R.|last8=Grundstrom|first8=E. D.|last9=Ten Brummelaar|first9=T. A.|last10=Goldfinger|first10=P. J.|last11=Sturmann|first11=L.|last12=Sturmann|first12=J.|last13=Turner|first13=N. H.|last14=Farrington|first14=C.|year=2013|doi=10.1088/0004-637X/768/2/128|s2cid=9488327}}

| gravity = 3.047

| rotational_velocity = 149

| age_myr = 70

}}

{{Starbox catalog

| names = η Tau, 25 Tau, HR 1165, HD 23630, BD+23 541, FK5 139, HIP 17702, SAO 76199, GC 4541, BDS 1875, CCDM 03474+2407

}}

{{Starbox reference

| Simbad = HD+23630

}}

{{Starbox end

}}

Alcyone {{IPAc-en|æ|l|'|s|ai|@|n|iː}},{{MW|Alcyone}} is a blue-white giant star and the brightest star in the Pleiades open cluster. At apparent magnitude 2.87, it is also the third-brightest star in the Taurus constellation. The star has the Bayer designation Eta Tauri, Latinized from η Tauri and abbreviated Eta Tau or η Tau. It is about 440 light-years distant.

Nomenclature

Eta Tauri is the star's Bayer designation. The name Alcyone originates in Greek mythology; she is one of the seven daughters of Atlas and Pleione known as the Pleiades. In 2016, the International Astronomical Union (IAU) organized a Working Group on Star Names (WGSN){{cite web | url=https://www.iau.org/science/scientific_bodies/working_groups/280/ | title=IAU Working Group on Star Names (WGSN)|accessdate=22 May 2016}} to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/WGSN_bulletin1.pdf | title=Bulletin of the IAU Working Group on Star Names, No. 1 |accessdate=28 July 2016}} included a table of the first two batches of names approved by the WGSN; which included Alcyone for this star. It is now so entered in the IAU Catalog of Star Names.{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt | title=IAU Catalog of Star Names |accessdate=28 July 2016}}

In Chinese, {{lang|zh|昴宿}} ({{lang|zh-Latn|Mǎo Xiù}}), meaning Hairy Head, refers to an asterism consisting Alcyone, Electra, Taygeta, Asterope, Maia, Merope, and Atlas.{{in lang|zh}} 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, {{ISBN|978-986-7332-25-7}}. Consequently, the Chinese name for Alcyone itself is {{lang|zh|昴宿六}} ({{lang|zh-Latn|Mǎo Xiù liù}}), "the Sixth Star of Hairy Head".{{in lang|zh}} [http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ala_alz.htm 香港太空館 - 研究資源 - 亮星中英對照表] {{webarchive|url=https://web.archive.org/web/20081025110153/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ala_alz.htm |date=2008-10-25 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.

Physical properties

Alcyone is a blue-white B-type giant, similar to the other bright B-type stars in the Pleiades cluster. With an apparent magnitude of +2.87 and absolute magnitude of −2.39, it is the brightest and most luminous star in the Pleiades. The spectral type of B7IIIe indicates that emission lines are present in its spectrum. Like many Be stars, Alcyone has created a gaseous disk flung into orbit around the star from its equator.

Alcyone has a high rotational velocity, which causes it to have an ellipsoidal shape. Its effective radius is almost ten times that of the Sun, but the actual radius is lesser at poles and greater at the equator. Its effective temperature is approximately 12,300 K, with the actual temperature being greater at the poles and lesser at the equator. Its bolometric luminosity is 2,030 times solar.

The age of the Pleiades is typically calculated to be around 130 million years, but Alcyone itself appears to be younger, less than 100 million years. Alcyone may be a blue straggler or models may not be deriving an accurate age for stars of this type.

Variability

File:AlcyoneLightCurve.png for Alcyone, adapted from White et al. (2017)]]

Alcyone has long been suspected to vary in brightness,{{cite journal |bibcode=1984PASP...96..105H |title=Binary stars unresolved by speckle interferometry. III. |last1=Hartkopf |first1=W. I. |last2=McAlister |first2=H. A. |journal=Publications of the Astronomical Society of the Pacific |date=1984 |volume=96 |page=105 |doi=10.1086/131309 }} and a 2017 study using data from the Kepler Space Telescope found definite periodic variations with amplitudes up to 0.001 magnitudes. This is considered undetectable by ground-based observations. The strongest period of 2.3 days is thought to be the rotation period of the star, with an uneven surface causing slight brightness changes, but there are also more rapid pulsations and Alcyone has been classified as both a rotational variable and a slowly pulsating B-type star.{{cite web |url=https://www.aavso.org/vsx/index.php?view=detail.top&oid=54210 |title=Alcyone |website=International Variable Star Index |access-date=2025-05-08 }}

As of 2025, Alcyone has not been formally listed as a variable star in the General Catalogue of Variable Stars.{{cite journal |bibcode=2017ARep...61...80S |title=General catalogue of variable stars: Version GCVS 5.1 |last1=Samus' |first1=N. N. |last2=Kazarovets |first2=E. V. |last3=Durlevich |first3=O. V. |last4=Kireeva |first4=N. N. |last5=Pastukhova |first5=E. N. |journal=Astronomy Reports |date=2017 |volume=61 |issue=1 |page=80 |doi=10.1134/S1063772917010085 }}

Companions

The Catalog of Components of Double and Multiple Stars lists three companions: B is 24 Tauri, a magnitude 6.28 A0 main-sequence star 117" away; C is V647 Tauri, a δ Sct variable star;{{cite journal|bibcode=2008A&A...483..567G|arxiv=0802.3148|title=Chemical composition of a and F dwarfs members of the Pleiades open cluster|journal=Astronomy and Astrophysics|volume=483|issue=2|pages=567|last1=Gebran|first1=M.|last2=Monier|first2=R.|year=2008|doi=10.1051/0004-6361:20079271|s2cid=18923359}} and D is a magnitude 9.15 F3 main-sequence star.{{cite journal|bibcode=1994CoORB.115.....D|title=Catalogue of the Components of Double and Multiple stars (CCDM). First edition|journal=Obs. R. Belg., Commun., Sér. A|volume=115|last1=Dommanget|first1=J.|last2=Nys|first2=O.|year=1994}} V647 Tau varies from magnitude +8.25 to +8.30 over 1.13 hours.

The Washington Double Star Catalog lists a further four companions, all fainter than 11th magnitude, and also describes component D as itself double with two nearly equal components separated by 0.30".{{cite journal|bibcode=2001AJ....122.3466M|title=The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog|journal=The Astronomical Journal|volume=122|issue=6|pages=3466|last1=Mason|first1=Brian D.|last2=Wycoff|first2=Gary L.|last3=Hartkopf|first3=William I.|last4=Douglass|first4=Geoffrey G.|last5=Worley|first5=Charles E.|year=2001|doi=10.1086/323920|doi-access=free}}

Some previous lunar occultation studies found evidence of sub-arcsecond companions, but more recently, a 2021 interferometric study concluded that Alcyone is a single star system.{{Cite journal |last1=Hutter |first1=D. J. |last2=Tycner |first2=C. |last3=Zavala |first3=R. T. |last4=Benson |first4=J. A. |last5=Hummel |first5=C. A. |last6=Zirm |first6=H. |date=2021-12-01 |title=Surveying the Bright Stars by Optical Interferometry III: A Magnitude-Limited Multiplicity Survey of Classical Be-Stars |arxiv=2109.06839 |journal=The Astrophysical Journal Supplement Series |volume=257 |issue=2 |pages=69 |doi=10.3847/1538-4365/ac23cb |bibcode=2021ApJS..257...69H |s2cid=237503492 |issn=0067-0049 |doi-access=free }}

References

{{reflist|refs=

{{cite journal |bibcode=2015ApJ...807...58B |title=Bayesian Ages for Early-type Stars from Isochrones Including Rotation, and a Possible Old Age for the Hyades |last1=Brandt |first1=Timothy D. |last2=Huang |first2=Chelsea X. |journal=The Astrophysical Journal |date=2015 |volume=807 |issue=1 |page=58 |doi=10.1088/0004-637X/807/1/58 |arxiv=1501.04404 |s2cid=119045213 }}

{{cite journal | title=Validation of the new Hipparcos reduction | last1=van Leeuwen | first1=F. | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–664 | year=2007 | arxiv=0708.1752 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 | s2cid=18759600}} [http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=I/311/hip2&recno=17659 Vizier catalog entry ]

{{cite journal | title=Beyond the Kepler/K2 bright limit: Variability in the seven brightest members of the Pleiades | last1=White | first1=T. R. | last2=Pope | first2=B. J. S. | last3=Antoci | first3=V. | last4=Pápics | first4=P. I. | last5=Aerts | first5=C. | last6=Gies | first6=D. R. | last7=Gordon | first7=K. | last8=Huber | first8=D. | last9=Schaefer | first9=G. H. | last10=Aigrain | first10=S. | last11=Albrecht | first11=S. | last12=Barclay | first12=T. | last13=Barentsen | first13=G. | last14=Beck | first14=P. G. | last15=Bedding | first15=T. R. | last16=Fredslund Andersen | first16=M. | last17=Grundahl | first17=F. | last18=Howell | first18=S. B. | last19=Ireland | first19=M. J. | last20=Murphy | first20=S. J. | last21=Nielsen | first21=M. B. | last22=Silva Aguirre | first22=V. | last23=Tuthill | first23=P. G. | display-authors=1 | journal=Monthly Notices of the Royal Astronomical Society | volume=471 | issue=3 | pages=2882–2901 | year=2017 | arxiv=1708.07462 | bibcode=2017MNRAS.471.2882W | doi=10.1093/mnras/stx1050 | doi-access=free | s2cid=119221178 }}

}}

External links

Jim Kaler's Stars, University of Illinois:[http://stars.astro.illinois.edu/sow/alcyone.html ALCYONE (Eta Tauri)]
[http://www.alcyone.com/info.html#alcyone Alcyone and the Pleiades]

Tauri, Eta

Category:Taurus (constellation)

Category:B-type giants

Category:A-type main-sequence stars

Category:F-type main-sequence stars

Category:Eclipsing binaries

Category:Delta Scuti variables