SU Ursae Majoris

{{short description|Variable star in the constellation Ursa Major}}

{{Starbox begin

| name = SU Ursae Majoris

}}

{{Starbox image

| image = 250px

| caption = A visual band light curve for the April 1989 superoutburst of SU Ursae Majoris, adapted from Udalski et al. (1990)

}}

{{Starbox observe

| epoch = J2000

| constell = Ursa Major

| ra = {{RA|08|12|28.26946}}

| dec = {{DEC|+62|36|22.4280}}

| appmag_v = 10.8–14.96

}}

{{Starbox character

| type =

| class =

| b-v =

| u-b =

| variable = SU UMa

}}

{{Starbox astrometry

| radial_v = +27.0

| prop_mo_ra = +6.582

| prop_mo_dec = −24.538

| parallax = 4.5347

| p_error = 0.0286

| parallax_footnote =

| absmag_v = +5.1

}}

{{Starbox orbit

| reference =

| period_unitless = {{Val|0.076351|0.000043|u=days|fmt=none}}

| periastron = {{Val|2446143.6672|0.0015|u=HJD|fmt=commas}}

| k1 = {{Val|59|7|u=km s^–1}}

| inclination = 42

}}

{{Starbox detail

| source =

| component1 = White dwarf

| mass = 0.8

| radius =

| luminosity =

| gravity =

| temperature = 28,000

| metal_fe =

| rotational_velocity =

| component2 = Red dwarf

| mass2 = 0.105

| radius2 = 0.167

| luminosity2 =

| gravity2 =

| temperature2 =

| metal_fe2 =

| rotational_velocity2 =

| age_myr2 =

}}

{{Starbox catalog

| names={{odlist | V=SU UMa | 2MASS=J08122826+6236224 | name=AAVSO 0803+62 }}

}}

{{Starbox reference

| Simbad = SU+UMa

}}

SU Ursae Majoris, or SU UMa, is a close binary star in the northern circumpolar constellation of Ursa Major. It is a periodic cataclysmic variable that varies in magnitude from a peak of 10.8 down to a base of 14.96. The distance to this system, as determined from its annual parallax shift of {{Val|4.53|ul=mas}}, is 719 light-years. It is moving further from the Earth with a heliocentric radial velocity of +27 km/s.

The variable nature of this star was discovered at the Moscow Observatory by Lidiya Tseraskaya (L. Ceraski) in 1908. It was classified as a U Geminorum-type variable, or dwarf nova. Observation since 1926 showed that this variable undergoes two different types of eruptions: a short maxima lasting around two days that ranged in brightness between 11.6–12.9 magnitude, and a longer maxima extending for 13 days that ranged between 10.4–11.8 magnitude. The later event came to be referred to as 'supermaxima'. Similar dwarf novae of this class have since been discovered, and SU UMa is now the prototype for this sub-category of variable stars.

This is a single-lined spectroscopic binary with an orbital period of {{Convert|0.076351|d|h|2|abbr=off|disp=out}}. It consists of a white dwarf star that is acquiring matter from its close companion via an accretion disk. This disk is unstable and undergoes periodic outbursts which increase the luminosity of the system. For SU UMa, the accretion rate from the companion is {{Val|9.8e-13|u={{solar mass}}·yr⁻¹}}. X-ray emission has been detected in the vicinity of the white dwarf, which drops by a factor of four during outbursts. This emission is theorized to come from the boundary layer between the white dwarf and its accretion disk.

References

{{reflist|refs=

{{cite journal |last1=Udalski |first1=A. |title=SU Ursae Majoris: The Perfect Prototype of SU UMa Subclass of Dwarf Novae |journal=The Astronomical Journal |date=July 1990 |volume=100 |pages=226 |doi=10.1086/115508 |bibcode=1990AJ....100..226U |url=https://ui.adsabs.harvard.edu/abs/1990AJ....100..226U |access-date=22 April 2022}}

{{cite journal

| title=Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Radial velocities: The Wilson-Evans-Batten catalogue

| display-authors=1 | last1=Duflot | first1=M.

| last2=Figon | first2=P. | last3=Meyssonnier | first3=N.

| journal=Astronomy and Astrophysics Supplement

| volume=114 | page=269 | date=December 1995

| bibcode=1995A&AS..114..269D }}

{{cite journal

| 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

| volume=61 | issue=1 | pages=80 | year=2017

| doi=10.1134/S1063772917010085 | bibcode=2017ARep...61...80S | s2cid=125853869 }}

{{cite journal

| title=Une variable nouvelle 5.1908 Ursae majoris

| last1=Ceraski | first1=W.

| journal=Astronomische Nachrichten

| volume=177 | issue=11 | page=173 | date=February 1908

| doi=10.1002/asna.19081771105 | bibcode=1908AN....177..173C | url=https://zenodo.org/record/1907659 }}

{{cite journal

| title=Binary Stars among Cataclysmic Variables. VI. on the Mean Absolute Magnitude of U Geminorum Variables

| last1=Kraft | first1=Robert P. | last2=Luyten | first2=Willem J.

| journal=The Astrophysical Journal

| volume=142 | page=1041 | date=October 1965

| doi=10.1086/148374 | bibcode=1965ApJ...142.1041K }}

{{cite journal

| title=SU UMa, 1926-54

| last1=Isles | first1=J. E.

| journal=Journal of the British Astronomical Association

| volume=84 | pages=365–373 | year=1974

| bibcode=1974JBAA...84..365I}}

{{cite journal

| title=Superoutburst : a general phenomenon in dwarf novae

| last1=van Paradijs | first1=J.

| journal=Astronomy and Astrophysics

| volume=125 | pages=L16–L18 | date=September 1983

| bibcode=1983A&A...125L..16V}}

{{cite journal

| title=A Spectroscopic Study of the Cataclysmic Binary Star SU Ursae Majoris

| display-authors=1 | last1=Thorstensen | first1=John R.

| last2=Wade | first2=Richard A. | last3=Oke | first3=J. B.

| journal=Astrophysical Journal | volume=309 | pages=721

| date=October 1986 | doi=10.1086/164641 | bibcode=1986ApJ...309..721T | doi-access=free }}

{{cite journal

| title=Spectral and photometric behavior of SU UMa during quiescence and outburst states

| display-authors=1 | last1=Zead | first1=I.

| last2=Saad | first2=S. M. | last3=Sanad | first3=M. R.

| last4=Behary | first4=M. M. | last5=Gadallah | first5=K.

| journal=New Astronomy

| volume=52 | pages=122–132 | date=April 2017

| doi=10.1016/j.newast.2016.10.010 | bibcode=2017NewA...52..122Z }}

{{cite journal

| title=X-ray observations of SU UMa throughout six outbursts

| last1=Collins | first1=David J. | last2=Wheatley | first2=Peter J.

| journal=Monthly Notices of the Royal Astronomical Society

| volume=402 | issue=3 | pages=1816–1823 | date=March 2010

| doi=10.1111/j.1365-2966.2009.16009.x | doi-access=free | bibcode=2010MNRAS.402.1816C | arxiv=0911.2711 | s2cid=118649844 }}

{{cite journal|doi=10.1111/j.1365-2966.2010.17881.x|title=Distances and absolute magnitudes of dwarf novae: Murmurs of period bounce|journal=Monthly Notices of the Royal Astronomical Society|volume=411|issue=4|pages=2695–2716|year=2011|last1=Patterson|first1=Joseph|bibcode=2011MNRAS.411.2695P|doi-access=free|arxiv=0903.1006}}

{{cite journal|bibcode=2006ApJ...642.1029U|arxiv=astro-ph/0602126|title=The Dwarf Novae during Quiescence|journal=The Astrophysical Journal|volume=642|issue=2|pages=1029–1041|last1=Urban|first1=Joel A|last2=Sion|first2=Edward M|year=2006|doi=10.1086/501430|s2cid=1434460}}

{{cite journal|bibcode=2006MNRAS.373..484K|arxiv=astro-ph/0609671|title=The donor stars of cataclysmic variables|journal=Monthly Notices of the Royal Astronomical Society|volume=373|issue=2|pages=484–502|last1=Knigge|first1=Christian|last2=Sion|first2=Edward M|year=2006|doi=10.1111/j.1365-2966.2006.11096.x|doi-access=free |s2cid=2616606}}

}}

SU Ursae Majoris

See also

References

Further reading