FU Orionis

{{about|the particular star|the type of variable stars named after this star|FU Orionis stars}}

{{Starbox begin

{{Starbox image

| image = 300px

| caption = Barnard 35, a part of the Lambda Orionis Ring seen by the Spitzer Space Telescope. FU Orionis is the bright star at lower right.

}}

{{Starbox observe

| epoch = J2000.0

| equinox = J2000.0 (ICRS)

| constell = Orion

| ra = {{RA|05|45|22.362}}{{cite simbad|title=V* FU Ori|accessdate=December 8, 2008}}

| dec = {{DEC|+09|04|12.31}}

| appmag_v=8.94

}}

{{Starbox character

| class = uncertain + K{{val|5|2|1}}

| b-v = 1.41

| variable = FU OriFU Ori, database entry, [http://www.sai.msu.su/groups/cluster/gcvs/gcvs/iii/iii.dat The combined table of GCVS Vols I-III and NL 67-78 with improved coordinates, General Catalogue of Variable Stars] {{Webarchive|url=https://web.archive.org/web/20170620004609/http://www.sai.msu.su/groups/cluster/gcvs/gcvs/iii/iii.dat |date=2017-06-20 }}, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line December 8, 2008.

}}

{{Starbox astrometry

|radial_v=

|prop_mo_ra={{val|+2.218|0.079}}{{Cite journal|last=Gaia Collaboration|date=2018-08-01|title=Gaia Data Release 2 - Summary of the contents and survey properties|journal=Astronomy & Astrophysics|language=en|volume=616|pages=A1|arxiv=1804.09365|doi=10.1051/0004-6361/201833051|bibcode=2018A&A...616A...1G|s2cid=49211658|issn=0004-6361}}

|prop_mo_dec={{val|-2.834|0.065}}

|parallax=2.4029

|p_error=0.0497

| parallax_footnote =

}}

{{Starbox detail

|source=

|component1= FU Orionis north

|mass= 0.6

|radius=10.42

|luminosity=

|temperature=5095.1

|age_myr=

|component2= FU Orionis south

|mass2= 1.2

|radius2=

|luminosity2=

|temperature2= 4350

|age_myr2= ~2

}}

{{Starbox catalog

| names={{odlist | V=FU Ori |BD=+09°5427}}

}}

{{Starbox reference

| Simbad=FU+Ori

}}

FU Orionis is a variable and binary star{{Cite journal|last1=Wang|first1=Hongchi|last2=Apai|first2=Dániel|last3=Henning|first3=Thomas|last4=Pascucci|first4=Ilaria|author4-link=Ilaria Pascucci|date=January 2004|title=FU Orionis: A Binary Star?|journal=Astrophysical Journal Letters|language=en|volume=601|issue=1|pages=L83–L86|doi=10.1086/381705|arxiv=astro-ph/0311606|bibcode=2004ApJ...601L..83W|s2cid=17793369|issn=0004-637X|doi-access=free}} 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.[https://www.aavso.org/vsots_fuori AAVSO: FU Orionis] The name FU Orionis is a variable star designation in the Argelander system, which are assigned sequentially as new variables are discovered. FU Orionis is about 1,360 light years distant and is associated with the molecular cloud Barnard 35.{{Cite journal|last1=Smith|first1=H. A.|last2=Thronson|first2=H. A.|last3=Lada|first3=C. J.|last4=Harper|first4=D. A.|last5=Loewenstein|first5=R. F.|last6=Smith|first6=J.|date=July 1982|title=Far-infrared observations of FU Ori.|journal=Astrophysical Journal|language=en|volume=258|pages=170–176|doi=10.1086/160065|bibcode=1982ApJ...258..170S|issn=0004-637X|doi-access=free}}

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

Image:FUOriLightCurve.png light curve for FU Orionis, adapted from Clarke et al. (2005). The inset plot, adapted from Siwak, et al. (2013), illustrates the short timescale variability.]]

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 ¹²CO 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.{{Cite journal|last1=Pérez|first1=Sebastián|last2=Hales|first2=Antonio|last3=Liu|first3=Hauyu Baobab|last4=Zhu|first4=Zhaohuan|last5=Casassus|first5=Simon|last6=Williams|first6=Jonathan|last7=Zurlo|first7=Alice|last8=Cuello|first8=Nicolás|last9=Cieza|first9=Lucas|last10=Principe|first10=David|date=January 2020|title=Resolving the FU Orionis System with ALMA: Interacting Twin Disks?|journal=Astrophysical Journal|language=en|volume=889|issue=1|pages=59|doi=10.3847/1538-4357/ab5c1b|issn=0004-637X|arxiv=1911.11282|bibcode=2020ApJ...889...59P|s2cid=208291454 |doi-access=free }}

The primary, called FU Orionis north has a mass of 0.6 {{Solar mass|link=true}} and accretes $3.8 \times 10^{-5}$ {{Solar mass}} per year. The primary has an uncertain spectral type and luminosity class. 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.{{Cite journal|last1=Siwak|first1=Michał|last2=Winiarski|first2=Maciej|last3=Ogłoza|first3=Waldemar|last4=Dróżdż|first4=Marek|last5=Zoła|first5=Stanisław|last6=Moffat|first6=Anthony F. J.|last7=Stachowski|first7=Grzegorz|last8=Rucinski|first8=Slavek M.|last9=Cameron|first9=Chris|last10=Matthews|first10=Jaymie M.|last11=Weiss|first11=Werner W.|date=October 2018|title=Insights into the inner regions of the FU Orionis disc|journal=Astronomy & Astrophysics|language=en|volume=618|pages=A79|doi=10.1051/0004-6361/201833401|arxiv=1807.09134|bibcode=2018A&A...618A..79S|issn=0004-6361|doi-access=free}} The secondary, called FU Orionis south could be the more massive component in the system with 1.2 {{Solar mass}} and a spectral type of about K5.{{Cite journal|last1=Beck|first1=Tracy L.|last2=Aspin|first2=C.|date=March 2012|title=The Nature and Evolutionary State of the FU Orionis Binary System|journal=The Astronomical Journal|language=en|volume=143|issue=3|pages=55|doi=10.1088/0004-6256/143/3/55|bibcode=2012AJ....143...55B|issn=0004-6256|doi-access=free}}

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.{{Cite web|url=https://www.aavso.org/vsots_fuori|title=FU Orionis {{!}} aavso.org|website=www.aavso.org|access-date=2020-02-08}}

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. Simulations predict an extremely large radius of {{Jupiter radius|14|link=y}} or around {{Solar radius|1.4|link=y}} at the beginning of the extreme evaporation event.

{{OrbitboxPlanet begin

| table_ref =

}}

{{OrbitboxPlanet hypothetical

| exoplanet = b

| mass = ~6

| semimajor = ~0.08

| period = ~10-12

| eccentricity =

| inclination =

| radius = ~14

}}

References

{{reflist|refs=

{{cite journal |last1=Clarke |first1=C. |last2=Lodato |first2=G. |last3=Melnikov |first3=S. Y. |last4=Ibrahimov |first4=M. A. |title=The photometric evolution of FU Orionis objects: disc instability and wind–envelope interaction |journal=Monthly Notices of the Royal Astronomical Society |date=August 2005 |volume=361 |issue=3 |pages=942–954 |doi=10.1111/j.1365-2966.2005.09231.x |arxiv=astro-ph/0505515 |bibcode=2005MNRAS.361..942C |doi-access=free }}

{{cite journal |last1=Siwak |first1=Michal |last2=Rucinski |first2=Slavek M. |last3=Matthews |first3=Jaymie M. |last4=Kuschnig |first4=Rainer |last5=Guenther |first5=David B. |last6=Moffat |first6=Anthony F. J. |last7=Rowe |first7=Jason F. |last8=Sasselov |first8=Dimitar |last9=Weiss |first9=Werner W. |title=Photometric variability in FU Ori and Z CMa as observed by MOST |journal=Monthly Notices of the Royal Astronomical Society |date=June 2013 |volume=432 |issue=1 |pages=194–199 |doi=10.1093/mnras/stt441 |arxiv=1303.2568 |bibcode=2013MNRAS.432..194S |doi-access=free }}

{{cite journal

| title=Designation of Variable Stars

| last=Townley | first=S. D.

| journal=Publications of the Astronomical Society of the Pacific

| volume=27 | issue=161 | page=209 | date=December 1915

| doi=10.1086/122431 | bibcode=1915PASP...27..209T | doi-access=free }}

{{cite journal |last1=Stassun |first1=Keivan G. |last2=Oelkers |first2=Ryan J. |display-authors=etal |date=October 2019 |title=The Revised TESS Input Catalog and Candidate Target List |journal=The Astronomical Journal |volume=158 |issue=4 |pages=138 |doi=10.3847/1538-3881/ab3467 |doi-access=free |arxiv=1905.10694 |bibcode=2019AJ....158..138S}}

{{cite journal |last1=Nayakshin |first1=Sergei |last2=Owen |first2=James E. |last3=Elbakyan |first3=Vardan |date=July 2023 |title=Extreme evaporation of planets in hot thermally unstable protoplanetary discs: the case of FU Ori |journal=Monthly Notices of the Royal Astronomical Society |volume=523 |issue=1 |pages=385–403 |doi=10.1093/mnras/stad1392 |doi-access=free |arxiv=2305.03392 |bibcode=2023MNRAS.523..385N}}

{{cite journal |last1=Nayakshin |first1=Sergei |last2=Elbakyan |first2=Vardan |date=February 2024 |title=On the origin of accretion bursts in FU Ori |journal=Monthly Notices of the Royal Astronomical Society |volume=528 |issue=2 |pages=2182–2198 |doi=10.1093/mnras/stae049 |doi-access=free |arxiv=2309.12072 |bibcode=2024MNRAS.528.2182N}}

}}

External links

[https://www.aavso.org/vsots_fuori AAVSO Variable Star of the Month. FU Ori: February 2002]
[http://www.nightskyinfo.com/archive/fu_orionis/ FU Orionis] at NightSkyInfo.com

Category:FU Orionis stars

Category:G-type supergiants

Category:Orion (constellation)

Category:Durchmusterung objects

Orionis, FU

Category:Binary stars