epsilon Coronae Australis

{{Short description|Variable star in the constellation Corona Australis}}

{{Starbox image

| image = 250px

| caption = A light curve for Epsilon Coronae Australis plotted from TESS data

}}

{{Starbox observe

|epoch=J2000

|constell=Corona Australis

|ra={{RA|18|58|43.37714}}

|dec={{DEC|-37|06|26.4865}}

|appmag_v=+4.75

}}

{{Starbox character

|class=F4V Fe-0.8

|b-v=+0.39

|u-b=+0.01

|variable=W UMa

}}

{{Starbox astrometry

|radial_v=57.90 ± 1.2

|prop_mo_ra=−132.40

|prop_mo_dec=−110.62

|parallax=33.13

|p_error=0.33

|parallax_footnote=

|absmag_v=2.21

}}

{{Starbox orbit

|reference=

|period_unitless=0.59143357 ± 0.00000016 d

|axis_unitless={{solar radius|3.795 ± 0.052}}

|eccentricity=0

|inclination=73.05 ± 0.16

|node=2.0113 ± 0.0033

|periastron=JD 2442296.95907 ± 0.0070

}}

{{Starbox detail

|component1=ε CrA A

|mass=1.9

|rotational_velocity=148.5

|radius=2.167Radii were given as a ratio of the radius to the semi-major axis; the semi-major axis is {{solar radius|3.795}}.

|temperature=6481 ± 20

|component2=ε CrA B

|mass2=0.24

|radius2=0.869

|temperature2=5939 ± 19

}}

{{Starbox catalog

|names={{odlist | B=ε CrA | CD=−37°13001 | CPD=−37°8433 | HD=175813 | HIP=93174 | HR=7152 | SAO=210781 }}

}}

Epsilon Coronae Australis (ε CrA), is a star system located in the constellation Corona Australis. Varying in brightness between apparent magnitudes of 4.74 to 5 over 14 hours, it is the brightest W Ursae Majoris variable (low mass contact binary) in the night sky.

Naming

Nicolas Louis de Lacaille gave Epsilon Coronae Australis its Bayer designation. It is also known as HR 7152, and HD 175813.

Properties

Epsilon Coronae Australis is an F4V dwarf star with an effective temperature of 6000 Kelvin. It ranges between apparent magnitudes of 4.74 to 5 over 14 hours, an absolute magnitude of +2.45, and a mass of 1.1 solar masses. Epsilon Coronae Australis is a W Ursae Majoris variable, indicating that it has a contact companion within the Roche limit of the primary. The star is located at a distance of 30 pc (97 light years) from the Sun. Yildiz and colleagues estimated the age of the system at 2.83 ± 0.28 billion years based on study of the properties of the system and estimated rate of mass transfer. They found the current masses of the primary and secondary to be 1.72 ± 0.04 and 0.22 ± 0.02 solar masses respectively, from their original masses of 1.06 ± 0.03 and 2.18 ± 0.06 solar masses.

Notes

References

{{reflist|refs=

{{cite web

| title=MAST: Barbara A. Mikulski Archive for Space Telescopes

| url=https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html

| publisher=Space Telescope Science Institute |access-date=8 December 2021}}

{{cite journal|last=Yildiz|date=2014|title=Origin of W UMa-type contact binaries - age and orbital evolution|journal=Monthly Notices of the Royal Astronomical Society | volume=437 | issue=1 |pages=185–94 | doi=10.1093/mnras/stt1874 |doi-access=free |bibcode=2014MNRAS.437..185Y|arxiv = 1310.5526 }}

{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=10599 |title=Epsilon Coronae Australis |last=BSJ|date=4 January 2010|work=AAVSO Website|publisher=American Association of Variable Star Observers|accessdate= 22 January 2014}}

{{cite journal|doi=10.1111/j.1365-2966.2011.18741.x|title=Distance and temperature from absolute light curves of three eclipsing binaries|journal=Monthly Notices of the Royal Astronomical Society|volume=415|pages=596–604|year=2011|last1=Wilson|first1=R. E.|last2=Raichur|first2=H.|issue=1|bibcode = 2011MNRAS.415..596W |doi-access=free}}

{{cite journal| title = New absolute magnitude calibrations for W Ursa Majoris type binaries |author1=Eker, Z. |author2=Bilir, S. |author3=Yaz, E. |author4=Demircan, O. |author5=Helvaci, M. |journal=Astronomische Nachrichten |volume=330 |issue = 1|pages= 68–77 |date=2009|doi=10.1002/asna.200811041 |bibcode=2009AN....330...68E|arxiv = 0807.4989 |s2cid=15071352 }}

{{citation | last1=Schröder | first1=C. | last2=Reiners | first2=Ansgar | last3=Schmitt | first3=Jürgen H. M. M. | title=Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo | journal=Astronomy and Astrophysics | volume=493 | issue=3 | pages=1099–1107 | date=January 2009 | doi=10.1051/0004-6361:200810377 | bibcode=2009A&A...493.1099S | doi-access=free | url=http://goedoc.uni-goettingen.de/goescholar/bitstream/handle/1/9690/aa10377-08.pdf?sequence=2 }}{{Dead link|date=September 2023 |bot=InternetArchiveBot |fix-attempted=yes }}

{{cite journal|doi=10.1111/j.1365-2966.2005.08609.x|arxiv=astro-ph/0411291|title=Kinematics of W Ursae Majoris type binaries and evidence of the two types of formation|journal=Monthly Notices of the Royal Astronomical Society|volume=357|issue=2|pages=497–517|year=2005|last1=Bilir|first1=S.|last2=Karataş|first2=Y.|last3=Demircan|first3=O.|last4=Eker|first4=Z.|doi-access=free |bibcode = 2005MNRAS.357..497B |s2cid=16274339}}

{{cite journal|title=Validation of the new Hipparcos reduction|url=http://www.aanda.org/index.php?option=com_article&access=bibcode&Itemid=129&bibcode=2007A%2526A...474..653VFUL|author1=van Leeuwen, F.|display-authors=etal|journal=Astronomy and Astrophysics|volume=474|issue=2|pages=653–664|date=2007|arxiv=0708.1752|bibcode=2007A&A...474..653V|doi=10.1051/0004-6361:20078357|s2cid = 18759600}}

{{cite journal|doi=10.1086/504637|arxiv=astro-ph/0603770|title=Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc--The Southern Sample|journal=The Astronomical Journal|volume=132|pages=161–170|year=2006|last1=Gray|first1=R. O.|last2=Corbally|first2=C. J.|last3=Garrison|first3=R. F.|last4=McFadden|first4=M. T.|last5=Bubar|first5=E. J.|last6=McGahee|first6=C. E.|last7=O'Donoghue|first7=A. A.|last8=Knox|first8=E. R.|issue=1|bibcode = 2006AJ....132..161G |s2cid=119476992}}

{{cite journal|author1=Mermilliod, J.-C.|title=Compilation of Eggen's UBV data, transformed to UBV (unpublished)|journal=Catalogue of Eggen's UBV Data|url=http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?1986EgUBV........0M&db_key=AST&nosetcookie=1|date=1986|bibcode= 1986EgUBV........0M }}

}}

Category:Corona Australis

Corona Australis, Epsilon

Category:W Ursae Majoris variables

Category:Durchmusterung objects

7152

175813

093174