FU Orionis

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FU Orionis
FUOriLightCurve.png
The blue band light curve for FU Orionis, adapted from Clarke et al. (2005). [1] The inset plot, adapted from Siwak, et al. (2013), [2] illustrates the short timescale variability.
Observation data
Epoch J2000.0        Equinox J2000.0 (ICRS)
Constellation Orion
Right ascension 05h 45m 22.362s [3]
Declination +09° 04′ 12.31″ [3]
Apparent magnitude  (V)8.94 [3]
Characteristics
Spectral type uncertain + K5+2
−1 [4]
B−V color index 1.41 [3]
Variable type FU Ori [5]
Astrometry
Proper motion (μ)RA: 2.218 ± 0.079 [6]   mas/yr
Dec.: -2.834 ± 0.065 [6]   mas/yr
Parallax (π)2.4029 ± 0.0497  mas [6]
Distance 1,360 ± 30  ly
(416 ± 9  pc)
Details
FU Orionis north
Mass 0.6 [7]   M☉
Radius 10.42 [8]   R☉
Temperature 5095.1 [8]   K
FU Orionis south
Mass 1.2 [4]   M☉
Temperature 4350 [4]   K
Age ~2 [4]   Myr
Other designations
FU Ori, BD+09 5427. [3]
Database references
SIMBAD data

FU Orionis is a variable and binary star [9] system in the constellation of Orion, that in 1937 rose in apparent visual magnitude from 16.5 to 9.6, and has since been around magnitude 9. [10] [3] The name FU Orionis is a variable star designation in the Argelander system, which are assigned sequentially as new variables are discovered. [11] FU Orionis is about 1,360 light years distant and is associated with the molecular cloud Barnard 35. [6] [12]

Contents

For a long time this variable was considered unique, but in 1970 a similar star, V1057 Cygni, was discovered, and a number of additional examples have been discovered since then. These stars constitute the FU Orionis class of variable stars, GCVS type FU, often nicknamed FUors. These stars are pre–main sequence stars which display an extreme change in magnitude and spectral type.

Stellar system

FU Orionis consists of two components, both surrounded by a circumstellar disk. Both disks were resolved with ALMA. The primary is surrounded by a dust disk with a radius of 11  astronomical units and the secondary disk has a similar inclination and size. The disks are separated by about 250 au. The 12 CO emission show a complex kinematic environment and signatures of disk rotation, which are asymmetric. The asymmetry of the disk rotation is explained with interactions of the disks during a stellar flyby. [7]

The primary, called FU Orionis north has a mass of 0.6  M☉ and accretes M☉ per year. [7] The primary has an uncertain spectral type and luminosity class. [4] FU Orionis stars do not show strong emission lines during the outburst and have spectral features that resemble F- or G-type supergiants during the maximum. The outer parts of FU Orionis stars produce a K-M supergiant spectrum, which can be observed in the near-infrared. [13] The secondary, called FU Orionis south could be the more massive component in the system with 1.2 M☉ and a spectral type of about K5. [4]

Nebula

FU Orionis is associated with the molecular cloud Barnard 35 (part of the Lambda Orionis Ring) and close to the star an arc-shaped nebula is visible. Other FU Orionis stars are associated with an arc-shaped reflection nebula that becomes visible as the star brightens. [14] [12]

Hypothetical planet

A 2023 study proposed that FU Orionis north might be accreting matter from an evaporating planet about 6 times the mass of Jupiter. [15] Simulations predict an extremely large radius of 14  RJ or around 1.4  R☉ at the beginning of the extreme evaporation event. [16]

The FU Orionis planetary system [15] [16]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b(unconfirmed)~6 MJ ~0.08~10-12——~14  RJ

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<span class="mw-page-title-main">Alnilam</span> Star in the constellation Orion, in the center of the Orions Belt

Alnilam is the central star of Orion's Belt in the equatorial constellation of Orion. It has the Bayer designation ε Orionis, which is Latinised to Epsilon Orionis and abbreviated Epsilon Ori or ε Ori. This is a massive, blue supergiant star some 1,200 light-years distant. It is estimated to be 419,600 times as luminous as the Sun, and 40 times as massive.

<span class="mw-page-title-main">Bellatrix</span> Star in the constellation Orion

Bellatrix is the third-brightest star in the constellation of Orion, positioned 5° west of the red supergiant Betelgeuse. It has the Bayer designation γ Orionis, which is Latinized to Gamma Orionis. With a slightly variable magnitude of around 1.6, it is typically the 25th-brightest star in the night sky. Located at a distance of 250±10 light-years from the Sun, it is a blue giant star around 7.7 times as massive as the sun with 5.75 times its diameter.

<span class="mw-page-title-main">FU Orionis star</span>

In stellar evolution, an FU Orionis star is a pre–main-sequence star which displays an extreme change in magnitude and spectral type. One example is the star V1057 Cyg, which became six magnitudes brighter and went from spectral type dKe to F-type supergiant during 1969-1970. These stars are named after their type-star, FU Orionis.

<span class="mw-page-title-main">Upsilon Orionis</span> Star in the constellation Orion

Upsilon Orionis (υ Ori, υ Orionis) is a star in the constellation Orion. It has the traditional name Thabit or Tabit (ﺛﺎﺑﺖ, Arabic for "the endurer"), a name shared with Pi3 Orionis. It is a blue-white main sequence star of apparent magnitude 4.62 located over 3000 light-years distant from the Solar System. It is a suspected Beta Cephei variable.

<span class="mw-page-title-main">Sigma Orionis</span> Five-star system in the constellation Orion

Sigma Orionis or Sigma Ori is a multiple star system in the constellation Orion, consisting of the brightest members of a young open cluster. It is found at the eastern end of the belt, south west of Alnitak and west of the Horsehead Nebula which it partially illuminates. The combined brightness of the component stars is magnitude 3.80.

<span class="mw-page-title-main">S Persei</span> Red supergiant or hypergiant variable star in the constellation Perseus

S Persei is a red supergiant or hypergiant located near the Double Cluster in Perseus, north of the cluster NGC 869. It is a member of the Perseus OB1 association and one of the largest known stars. If placed in the Solar System, its photosphere would engulf the orbit of Jupiter. It is also a semiregular variable, a star whose variations are less regular than those of Mira variables.

<span class="mw-page-title-main">V1057 Cygni</span> Star in the constellation Cygnus

V1057 Cygni is a suspected binary star system in the northern constellation of Cygnus. It is a variable star of the FU Orionis-type, and was the second FU Orionis-type variable to be discovered. The system is located at a distance of approximately 3,000 light years from the Sun, in the North America Nebula. It has an apparent visual magnitude of around 12.4.

<span class="mw-page-title-main">U Orionis</span> Variable star in the constellation Orion

U Orionis is a Mira-type variable star in the constellation Orion. It is a classical long period variable star that has been well observed for over 120 years.

<span class="mw-page-title-main">25 Orionis</span> Star in the constellation Orion

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Theta<sup>2</sup> Orionis Star in the constellation Orion

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<span class="mw-page-title-main">BC Cygni</span> Star in the constellation Cygnus

BC Cygni is a red supergiant and pulsating variable star of spectral type M3.5Ia in the constellation Cygnus.

Theta<sup>1</sup> Orionis B Variable quadruple star system in the constellation Orion

Theta1 Orionis B, also known as BM Orionis, is a multiple star system containing at least five members. It is also one of the main stars of the Trapezium Cluster, with the others being A, C, and D. The primary is an eclipsing variable and one of the youngest known eclipsing binary systems.

<span class="mw-page-title-main">VV Orionis</span> Star in the constellation Orion

VV Orionis is an eclipsing binary located in the belt region of the constellation Orion. It is a faint naked eye star.

<span class="mw-page-title-main">RW Aurigae</span> Young binary star system in the constellation Auriga

RW Aurigae is a young binary system in the constellation of Auriga about 530 light years away, belonging to the Taurus-Auriga association of the Taurus Molecular Cloud. RW Aurigae B was discovered in 1944.

<span class="mw-page-title-main">BF Orionis</span> Young protostar system

BF Orionis is a young Herbig Ae/Be star in the constellation of Orion about 1250 light years away, within the Orion Nebula. It is the most massive star of the small birth cluster of four stars.

<span class="mw-page-title-main">EX Lupi</span>

EX Lupi is a young, single T-Tauri star in the southern constellation of Lupus. An irregular variable, it is the prototype of young, low-mass eruptive stars named EXors, with EX Lupi being this object's variable star designation. At its minimal activity level, EX Lupi resembles a classical T-Tauri star of the M0 dwarf type. The low latitude of this star, at a declination of −40°, makes it difficult for northern observers to view. Based on parallax measurements, it is located at a distance of about 505 light years from the Sun. The star lies next to a gap in the Lupus cloud complex, a star forming region.

<span class="mw-page-title-main">CQ Tauri</span> Star in the constellation Taurus

CQ Tauri is a young variable star in the equatorial constellation of Taurus. It is too faint to be visible to the naked eye with an apparent visual magnitude that ranges from 8.7 to 12.25. The distance to this star is approximately 487 light years based on parallax measurements, and it is drifting further away with a radial velocity of ~23 km/s. It appears to be part of the T-association Tau 4. CQ Tauri lies close enough to the ecliptic to undergo lunar occultations.

<span class="mw-page-title-main">UX Orionis</span> Variable star in the constellation Orion

UX Orionis is a variable star in the constellation of Orion. It is a Herbig Ae star, located about 1000 light years from the Earth. At its brightest it is a magnitude 9.5 object, so it is too faint to be seen with the naked eye. UX Orionis is the prototype of the UX Orionis class of variable stars, which are young stellar objects that exhibit large, irregular changes in visual band brightness. UX Orionis was discovered by Henrietta Swan Leavitt.

References

  1. ↑ Clarke, C.; Lodato, G.; Melnikov, S. Y.; Ibrahimov, M. A. (August 2005). "The photometric evolution of FU Orionis objects: disc instability and wind–envelope interaction". Monthly Notices of the Royal Astronomical Society. 361 (3): 942–954. arXiv: astro-ph/0505515 . Bibcode:2005MNRAS.361..942C. doi: 10.1111/j.1365-2966.2005.09231.x .
  2. ↑ Siwak, Michal; Rucinski, Slavek M.; Matthews, Jaymie M.; Kuschnig, Rainer; Guenther, David B.; Moffat, Anthony F. J.; Rowe, Jason F.; Sasselov, Dimitar; Weiss, Werner W. (June 2013). "Photometric variability in FU Ori and Z CMa as observed by MOST". Monthly Notices of the Royal Astronomical Society. 432 (1): 194–199. arXiv: 1303.2568 . Bibcode:2013MNRAS.432..194S. doi: 10.1093/mnras/stt441 .
  3. 1 2 3 4 5 6 "V* FU Ori". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved December 8, 2008.
  4. 1 2 3 4 5 6 Beck, Tracy L.; Aspin, C. (March 2012). "The Nature and Evolutionary State of the FU Orionis Binary System". The Astronomical Journal. 143 (3): 55. Bibcode:2012AJ....143...55B. doi: 10.1088/0004-6256/143/3/55 . ISSN   0004-6256.
  5. ↑ FU Ori, database entry, The combined table of GCVS Vols I-III and NL 67-78 with improved coordinates, General Catalogue of Variable Stars Archived 2017-06-20 at the Wayback Machine , Sternberg Astronomical Institute, Moscow, Russia. Accessed on line December 8, 2008.
  6. 1 2 3 4 Gaia Collaboration (2018-08-01). "Gaia Data Release 2 - Summary of the contents and survey properties". Astronomy & Astrophysics. 616: A1. arXiv: 1804.09365 . Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. ISSN   0004-6361. S2CID   49211658.
  7. 1 2 3 Pérez, Sebastián; Hales, Antonio; Liu, Hauyu Baobab; Zhu, Zhaohuan; Casassus, Simon; Williams, Jonathan; Zurlo, Alice; Cuello, Nicolás; Cieza, Lucas; Principe, David (January 2020). "Resolving the FU Orionis System with ALMA: Interacting Twin Disks?". Astrophysical Journal. 889 (1): 59. arXiv: 1911.11282 . Bibcode:2020ApJ...889...59P. doi: 10.3847/1538-4357/ab5c1b . ISSN   0004-637X. S2CID   208291454.
  8. 1 2 Stassun, Keivan G.; Oelkers, Ryan J.; et al. (October 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal . 158 (4): 138. arXiv: 1905.10694 . Bibcode:2019AJ....158..138S. doi: 10.3847/1538-3881/ab3467 .
  9. ↑ Wang, Hongchi; Apai, Dániel; Henning, Thomas; Pascucci, Ilaria (January 2004). "FU Orionis: A Binary Star?". Astrophysical Journal Letters. 601 (1): L83–L86. arXiv: astro-ph/0311606 . Bibcode:2004ApJ...601L..83W. doi: 10.1086/381705 . ISSN   0004-637X. S2CID   17793369.
  10. ↑ AAVSO: FU Orionis
  11. ↑ Townley, S. D. (December 1915). "Designation of Variable Stars". Publications of the Astronomical Society of the Pacific. 27 (161): 209. Bibcode:1915PASP...27..209T. doi: 10.1086/122431 .
  12. 1 2 Smith, H. A.; Thronson, H. A.; Lada, C. J.; Harper, D. A.; Loewenstein, R. F.; Smith, J. (July 1982). "Far-infrared observations of FU Ori". Astrophysical Journal. 258: 170–176. Bibcode:1982ApJ...258..170S. doi: 10.1086/160065 . ISSN   0004-637X.
  13. ↑ Siwak, Michał; Winiarski, Maciej; Ogłoza, Waldemar; Dróżdż, Marek; Zoła, Stanisław; Moffat, Anthony F. J.; Stachowski, Grzegorz; Rucinski, Slavek M.; Cameron, Chris; Matthews, Jaymie M.; Weiss, Werner W. (October 2018). "Insights into the inner regions of the FU Orionis disc". Astronomy & Astrophysics. 618: A79. arXiv: 1807.09134 . Bibcode:2018A&A...618A..79S. doi: 10.1051/0004-6361/201833401 . ISSN   0004-6361.
  14. ↑ "FU Orionis | aavso.org". www.aavso.org. Retrieved 2020-02-08.
  15. 1 2 Nayakshin, Sergei; Owen, James E.; Elbakyan, Vardan (July 2023). "Extreme evaporation of planets in hot thermally unstable protoplanetary discs: the case of FU Ori". Monthly Notices of the Royal Astronomical Society . 523 (1): 385–403. arXiv: 2305.03392 . Bibcode:2023MNRAS.523..385N. doi: 10.1093/mnras/stad1392 .
  16. 1 2 Nayakshin, Sergei; Elbakyan, Vardan (February 2024). "On the origin of accretion bursts in FU Ori". Monthly Notices of the Royal Astronomical Society . 528 (2): 2182–2198. arXiv: 2309.12072 . Bibcode:2024MNRAS.528.2182N. doi: 10.1093/mnras/stae049 .
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