FU Orionis

FU Orionis

In stellar evolution, FU Orionis objects (or FUors) are pre-main sequence stars which display an extreme change in magnitude and spectral type. One example is the star V1057 Cyg, which became 6 magnitudes brighter and went from spectral type dKe to F supergiant.

The current model associates the FU Orionis flare with abrupt mass transfer from an accretion disc onto a young, low mass T Tauri star. Mass accretion rates for these objects are estimated to be:

dot{M} approx 10^{-4} frac{M_igodot}{year}

The rise time of these eruptions is typically ~ 1 year, but can be much longer. The lifetime of this high accretion, high luminosity phase is on the order of decades. However, even with such a relatively short timespan, an FU Orionis object has yet to be observed shutting off. By comparing the number of Fuor outbursts to the rate of star formation in the solar neighborhood, it is estimated that the average young star undergoes approximately 10-20 Fuor eruptions over its lifetime.

The prototypes of this class are: [http://simbad.u-strasbg.fr/sim-id.pl?protocol=html&Ident=FU+Ori&NbIdent=1&Radius=10&Radius.unit=arcmin&CooFrame=FK5&CooEpoch=2000&CooEqui=2000&output.max=all&o.catall=on&output.mesdisp=N&Bibyear1=1983&Bibyear2=2005&Frame1=FK5&Frame2=FK4&Frame3=G&Equi1=2000.0&Equi2=1950.0&Equi3=2000.0&Epoch1=2000.0&Epoch2=1950.0&Epoch3=2000.0 FU Ori] , [http://simbad.u-strasbg.fr/sim-id.pl?protocol=html&Ident=V1057+cyg&NbIdent=1&Radius=10&Radius.unit=arcmin&CooFrame=FK5&CooEpoch=2000&CooEqui=2000&output.max=all&o.catall=on&output.mesdisp=N&Bibyear1=1983&Bibyear2=2005&Frame1=FK5&Frame2=FK4&Frame3=G&Equi1=2000.0&Equi2=1950.0&Equi3=2000.0&Epoch1=2000.0&Epoch2=1950.0&Epoch3=2000.0 V1057 Cyg] and [http://simbad.u-strasbg.fr/sim-id.pl?protocol=html&Ident=V1515+Cyg&NbIdent=1&Radius=10&Radius.unit=arcmin&CooFrame=FK5&CooEpoch=2000&CooEqui=2000&output.max=all&o.catall=on&output.mesdisp=N&Bibyear1=1983&Bibyear2=2005&Frame1=FK5&Frame2=FK4&Frame3=G&Equi1=2000.0&Equi2=1950.0&Equi3=2000.0&Epoch1=2000.0&Epoch2=1950.0&Epoch3=2000.0 V1515 Cyg] ; being the more recent addition the embedded protostar [http://simbad.u-strasbg.fr/sim-id.pl?protocol=html&Ident=V1647+Ori&NbIdent=1&Radius=10&Radius.unit=arcmin&CooFrame=FK5&CooEpoch=2000&CooEqui=2000&output.max=all&o.catall=on&output.mesdisp=N&Bibyear1=1983&Bibyear2=2005&Frame1=FK5&Frame2=FK4&Frame3=G&Equi1=2000.0&Equi2=1950.0&Equi3=2000.0&Epoch1=2000.0&Epoch2=1950.0&Epoch3=2000.0 V1647 Ori] , which erupted in 2004 January.

External links

* http://www.aavso.org/vstar/vsots/0202.shtml

References

*Juhan Frank, Andrew King, Derek Raine (2002). Accretion power in astrophysics, Third Edition, Cambridge University Press. ISBN 0-521-62957-8.


Wikimedia Foundation. 2010.

Игры ⚽ Поможем решить контрольную работу

Look at other dictionaries:

  • Orionis — Daten des Sternbildes Orion Deutscher Name Orion Lateinischer Name Orion Lateinischer Genitiv Orionis Lateinische Abkürzung Ori Lage auf Himmelsäquator Rektaszensio …   Deutsch Wikipedia

  • Mu Orionis — Aa/Ab/Ba/Bb Constelación Orión Ascensión recta α 06h 02m 23.00s Declinación δ +09º 38’ 50.2’’ Distancia …   Wikipedia Español

  • Theta¹ Orionis C — Datenbanklinks zu Theta1 Orionis C Doppelstern Theta1 Orionis C …   Deutsch Wikipedia

  • Phi Orionis — Starbox short name=φ¹ Orionis epoch=J2000.0 constell=Orion ra=5h 34m 49.2s dec=9° 29 22 spectral=B0V appmag v=+4.39 absmag v= 3.04 dist ly=1000 dist pc=306.75 names=37 Orionis HR 1876, HD 36822, FK5 208, SAO 112914, HIP 26176, BD +09 877, TD1… …   Wikipedia

  • Sigma Orionis — A/B/C/D/E Constelación Orión Ascensión recta α 05h 38m 44.8s Declinación δ 02º 36’ 00’’ Distancia …   Wikipedia Español

  • Sigma Orionis — A/B/C/D/E (σ Orionis) Données d observation (Époque J2000.0) Ascension droite 05h 38m 44.80s Déclinaison 02° 36′ 00.0″ Constellation Orion Magnitude apparente …   Wikipédia en Français

  • Ji2 Orionis — Constelación Orión Ascensión recta α 06h 03m 55.18s Declinación δ +20º 08’ 18.4’’ Distancia …   Wikipedia Español

  • Sigma Orionis — Datenbanklinks zu σ Orionis Doppelstern σ Orionis …   Deutsch Wikipedia

  • Pi3 Orionis — π3 Orionis La position de Pi3 Orionis (π3) dans la constellation d Orion. Données d observation (Époque J2000.0) Ascension droite 04h 49m …   Wikipédia en Français

  • Δ Orionis — Delta Orionis Delta Orionis Aab/B/C Données d observation (Époque J2000) Ascension droite 05h 32m 00.4s Déclinaison −00° 17′ 57″ Constellation Orion Magnitude apparente 2,23 (3,2/3 …   Wikipédia en Français

  • Tau Orionis — Constelación Orión Ascensión recta α 05h 17m 36.39s Declinación δ 06º 50’ 39.9’’ Distancia …   Wikipedia Español

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”