Electra (star)

{{short description|Blue-white giant star in the constellation of Taurus}}

{{Starbox begin

| name=Electra

}}

{{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 = 30

| x = 832 | y = 392

}}

| caption = Electra in the Pleiades cluster (circled)

}}

{{Starbox observe

| epoch=J2000

| ra={{RA|03|44|52.53688}}

| dec={{DEC|+24|06|48.0112}}

| appmag_v=3.70{{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=B6 IIIe

| b-v=−0.12{{cite journal

| bibcode=1966CoLPL...4...99J }}

| u-b=−0.40

| variable=

}}

{{Starbox astrometry

| radial_v=+10.9{{cite journal

|author1=Pearce, J. A. |author2=Hill, G. | year=1975

| title=A spectroscopic investigation of the Pleiades

| journal=Publications of the Dominion Astrophysical Observatory | volume=14 | issue=14 | pages=319–343

| bibcode=1975PDAO...14..319P }}

| prop_mo_ra=+20.84

| prop_mo_dec=−46.06

| parallax=8.06

| p_error=0.25

| parallax_footnote={{cite journal|arxiv=0708.1752 | bibcode=2007A&A...474..653V| title=Validation of the new Hipparcos reduction| journal=Astronomy and Astrophysics| volume=474| issue=2| pages=653–664| last1=Van Leeuwen| first1=F.| year=2007| doi=10.1051/0004-6361:20078357| s2cid=18759600}}

| absmag_v=−1.77{{cite journal|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|last1=Zhang|first1=P|last2=Liu|first2=C. Q|last3=Chen|first3=P. S|year=2006|doi=10.1007/s10509-006-9173-1|s2cid=122897957}}

| dist_ly = 444

| dist_pc = 136

| dist_footnote = {{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 }}

}}

{{Starbox detail

| mass=4.6-4.7

| radius={{val|6.06|0.14|0.15}}

| luminosity=940{{cite journal|bibcode=2000ASPC..214...13H|title=Physical Properties and Evolutionary Stage of Be Stars|journal=The be Phenomenon in Early-Type Stars|volume=214|pages=13|last1=Harmanec|first1=P|year=2000}}

| temperature={{val|fmt=commas|13,484|293}}

| gravity={{val|3.412|0.047}}

| metal=

| rotational_velocity=181{{cite journal

| volume=440 | issue=1 |date=September 2005

| pages=305–320 | doi=10.1051/0004-6361:20042229 | bibcode=2005A&A...440..305F|arxiv = astro-ph/0503381 |s2cid=19016751 }}

| age_myr=115{{cite journal |last1=Basri |first1=Gibor |last2=Marcy |first2=Geoffrey W. |last3=Graham |first3=James R. |title=Lithium in Brown Dwarf Candidates: The Mass and Age of the Faintest Pleiades Stars |year=1996 |journal=The Astrophysical Journal |volume=458 |pages=600–609 |doi=10.1086/176842 |bibcode=1996ApJ...458..600B }}

}}

{{Starbox catalog

| names=17 Tauri, BD+23 507, FK5 136, GC 4477, HD 23302, HIP 17499, HR 1142, SAO 76131, NSV 15755

}}

{{Starbox reference

|Simbad=17+Tau

}}

Electra {{IPAc-en|ə|'|l|ɛ|k|t|r|ə}},{{OED|Electra}} designated 17 Tauri, is a blue-white giant star in the constellation of Taurus located approximately 440 light years away. It is the third-brightest star in the Pleiades open star cluster (M45), visible to the naked eye with an apparent magnitude of 3.7. Like the other bright stars of the Pleiades, it is named for one of the Seven Sisters of Greek mythology.

Properties

File:The Pleiades Cluster.jpg Cluster in infrared with Electra at the very top of the frame]]

Electra has an apparent brightness of 3.72, the third-brightest of the stars in the group. It belongs to the spectral class B6 IIIe and is approximately 440 light-years from the Sun. A number of papers have reported Electra to be a multiple star, but these have been contradictory and never confirmed.{{cite journal| bibcode=2021ApJS..257...69H | title=Surveying the Bright Stars by Optical Interferometry. III. A Magnitude-limited Multiplicity Survey of Classical be Stars | 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. | journal=The Astrophysical Journal Supplement Series | year=2021 | volume=257 | issue=2 | page=69 | doi=10.3847/1538-4365/ac23cb | arxiv=2109.06839 | s2cid=237503492 | doi-access=free }}

The projected rotational velocity of this star is {{val|181|u=km/s}}, making it a fast rotator. This is the velocity component of the star's equatorial rotation along the line of sight to the Earth. The estimated inclination of the star's pole is {{val|46.8|1.6|u=°}}, giving it a true equatorial rotational velocity of {{val|320|18|u=km/s}}. The rapid rotation rate of this star flattens the poles and stretch the equator. This makes the surface gravity of the star non-uniform and causes temperature variation. This effect is known as gravity darkening, because it results in a variation of radiation by latitude. The rapid rotation extends the life span of the star by increasing the core density and reducing the radiation output.

This is classified as a Be star, which is a B-type star with prominent emission lines of hydrogen in its spectrum.{{cite journal

| journal=Astrophysical Journal, Part 1

| volume=339 | doi=10.1086/167306 | bibcode=1989ApJ...339..403G}} The Be stars have a rotation rate that is 1.5–2 times the rotation of normal B-type stars. This high rate of rotation may allow mass loss during even minor prominences.{{cite journal

|author1=Zorec, J. |author2=Frémat, Y. |author3=Cidale, L. | title=On the evolutionary status of Be stars. I. Field Be stars near the Sun

| journal=Astronomy and Astrophysics | volume=441

| issue=1 |date=October 2005 | pages=235–248

| doi=10.1051/0004-6361:20053051 | bibcode=2005A&A...441..235Z|arxiv = astro-ph/0509119 |s2cid=17592657 }} Changes in the radial velocity measurements indicate that this star may have a companion, which would make Electra a spectroscopic binary.{{cite journal

| journal=Astrophysical Journal | volume=142

| pages=1604–1615 |date=November 1965

| doi=10.1086/148440 | bibcode=1965ApJ...142.1604A

|s2cid=121363965 }}{{cite journal

|author1=Pearce, J. A. |author2=Hill, Graham | title=Four Suspected Spectroscopic Binaries in the Pleiades | journal=Publications of the Astronomical Society of the Pacific

| volume=83 | issue=494 | pages=493–495 | year=1971

| doi=10.1086/129161 | bibcode=1971PASP...83..493P| doi-access=free }} However, follow-up studies including interferometry have failed to confirm any companion star(s), so it is likely a single star.{{cite journal | title=Surveying the Bright Stars by Optical Interferometry. III. A Magnitude-limited Multiplicity Survey of Classical Be Stars | year=2021 | 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. | journal=The Astrophysical Journal Supplement Series | volume=257 | issue=2 | page=69 | doi=10.3847/1538-4365/ac23cb | arxiv=2109.06839 | bibcode=2021ApJS..257...69H | s2cid=237503492 | doi-access=free }}

File:ElectraLightCurve.png for Electra, adapted from White et al. (2017)]]

Electra may be a variable star, and it appears in the New Catalogue of Suspected Variable Stars as NSV 15755.

Low amplitude variability of the brightness of Electra was detected by Kepler/K2, and Fourier analysis of the star's light curve shows several periods of oscillation, the strongest being 1.107 and 1.165 days.{{cite journal |last1=White |first1=T. R. |display-authors=etal |title=Beyond the Kepler/K2 bright limit: variability in the seven brightest members of the Pleiades |journal=Monthly Notices of the Royal Astronomical Society |date=November 2017 |volume=471 |issue=3 |pages=2882–2901 |doi=10.1093/mnras/stx1050 |bibcode=2017MNRAS.471.2882W |doi-access=free |arxiv=1708.07462 }} The International Variable Star Index classifies it as a slowly pulsating B star.{{cite web |title=NSV 15755 |url=https://www.aavso.org/vsx/index.php?view=detail.top&oid=54190 |website=The International Variable Star Index |publisher=AAVSO |access-date=8 October 2022}}

Infrared observations of this star showed an excess level of radiation equal to about 0.5 magnitudes. This emission is probably from a gaseous disk created by radiation-driven mass loss and rapid rotation of the star. These disks are created by an ejection of material roughly every ten years, which then settles into the equatorial plane about the star. However, the bright nebulosity that surrounds this star makes the observation uncertain.{{cite journal

| journal=The Astrophysical Journal | volume=649

| issue=2 | pages=1028–1042 |date=October 2006

| doi=10.1086/506373 | bibcode=2006ApJ...649.1028G|arxiv = astro-ph/0606039 |s2cid=17227369 }}

Nomenclature

17 Tauri is the star's Flamsteed designation.

It bore the traditional name Electra.{{Cite book

| first=Richard Hinckley | last=Allen | year=1899

| page=[https://archive.org/details/bub_gb_5xQuAAAAIAAJ/page/n428 406] | title=Star-names and their meanings

| publisher=G. E. Stechert

| url=https://archive.org/details/bub_gb_5xQuAAAAIAAJ

| access-date=10 October 2009 }} Electra was one of the Pleiades sisters in Greek mythology. In 2016, the International Astronomical Union 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)

| publisher=International Astronomical Union

| access-date=22 May 2016 }} to catalogue and standardize proper names for stars. The WGSN approved the name Electra for this star on 21 August 2016 and 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 |access-date=28 July 2016}}