scholarly journals Expected FU Ori Outburst Amplitudes from the Optical to the Mid-infrared

2022 ◽  
Vol 6 (1) ◽  
pp. 6
Author(s):  
Lynne A. Hillenbrand ◽  
Antonio C. Rodriguez
Keyword(s):  
Steady State ◽  
Central Star ◽  
Young Stellar Objects ◽  
Viscous Heating ◽  
High State ◽  
Passive Heating ◽  
Stellar Objects ◽  
Mid Infrared ◽  
Accretion Rates ◽  
Fu Ori

Abstract Disks around young stellar objects (YSOs) consist of material that thermally emits the energy provided by a combination of passive heating from the central star, and active, viscous heating due to mass accretion. FU Ori stars are YSOs with substantially enhanced accretion rates in their inner disk regions. As a disk transitions from standard low-state, to FU Ori-like high-state accretion, the outburst manifests through photometric brightening over a broad range of wavelengths. We present results for the expected amplitudes of the brightening between ∼4000 Å and 8 μm—the wavelength range where FU Ori type outburst events are most commonly detected. Our model consists of an optically thick passive + active steady-state accretion disk with low and high accretion states.

scholarly journals The Observational Evidence for Accretion

1997 ◽  
Vol 182 ◽  
pp. 391-405 ◽  
Author(s):  
Lee Hartmann
Keyword(s):  
Large Range ◽  
Observational Evidence ◽  
Young Stars ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
T Tauri ◽  
Accretion Rates ◽  
Low Mass ◽  
Stellar Magnetospheres ◽  
Mass Ejection

Outflows from low-mass young stellar objects are thought to draw upon the energy released by accretion onto T Tauri stars. I briefly summarize the evidence for this accretion and outline present estimates of mass accretion rates. Young stars show a very large range of accretion rates, and this has important implications for both mass ejection and for the structure of stellar magnetospheres which may truncate T Tauri disks.

scholarly journals Models of Accretion Disks Around Young Stars

2004 ◽  
Vol 221 ◽  
pp. 403-410 ◽  
Author(s):  
Paola D'Alessio ◽  
Nuria Calvet ◽  
Lee Hartmann ◽  
James Muzerolle ◽  
Michael Sitko
Keyword(s):  
Accretion Disks ◽  
Young Stars ◽  
Stellar Surface ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Disk Structure ◽  
Accretion Rates ◽  
Accretion Shocks

We discuss the importance of accretion in calculating disk models for young stellar objects. In particular, we show that a disk inner rim, irradiated by both the star and the accretion shocks at the stellar surface, can naturally explain recent observations of DG Tau with the Keck interferometer. We present models for two objects, with mass accretion rates differing by almost two orders of magnitude, to illustrate the effects of accretion on the overall disk structure and emission.

scholarly journals Episodic accretion in focus: revealing the environment of FU Orionis-type stars

2018 ◽  
Vol 14 (S345) ◽  
pp. 87-90
Author(s):  
O. Fehér ◽  
Á. Kóspál ◽  
P. Ábrahám ◽  
M. R. Hogerheijde ◽  
Ch. Brinch ◽  
...  
Keyword(s):  
Accretion Disks ◽  
Accretion Rate ◽  
Central Star ◽  
Systematic Investigation ◽  
Young Stars ◽  
Young Stellar Objects ◽  
Circumstellar Disk ◽  
Stellar Objects ◽  
Evolutionary Phase ◽  
Intense Mass

AbstractThe earliest phases of star formation are characterised by intense mass accretion from the circumstellar disk to the central star. One group of young stellar objects, the FU Orionis-type stars exhibit accretion rate peaks accompanied by bright eruptions. The occurance of these outbursts might solve the luminosity problem of protostars, play a key role in accumulating the final star mass, and have a significant effect on the parameters of the envelope and the disk. In the framework of the Structured Accretion Disks ERC project, we are conducting a systematic investigation of these sources with millimeter interferometry to examine whether they represent normal young stars in exceptional times or they are unusual objects. Our results show that FU Orionis-type stars can be similar to both Class I and Class II systems and may be in a special evolutionary phase between the two classes with their infall-driven episodic eruptions being the main driving force of the transition.

scholarly journals Observational signatures of outbursting protostars - I: From hydrodynamic simulations to observations

2019 ◽  
Vol 487 (4) ◽  
pp. 5106-5117 ◽  
Author(s):  
Benjamin MacFarlane ◽  
Dimitris Stamatellos ◽  
Doug Johnstone ◽  
Gregory Herczeg ◽  
Giseon Baek ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Radiation Field ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Hydrodynamic Simulations ◽  
Long Wavelength ◽  
Fu Ori ◽  
Flux Increase

Abstract Accretion onto protostars may occur in sharp bursts. Accretion bursts during the embedded phase of young protostars are probably most intense, but can only be inferred indirectly through long-wavelength observations. We perform radiative transfer calculations for young stellar objects (YSOs) formed in hydrodynamic simulations to predict the long wavelength, sub-mm and mm, flux responses to episodic accretion events, taking into account heating from the young protostar and from the interstellar radiation field. We find that the flux increase due to episodic accretion events is more prominent at sub-mm wavelengths than at mm wavelengths; e.g. a factor of ∼570 increase in the luminosity of the young protostar leads to a flux increase of a factor of 47 at 250 $\mu$m but only a factor of 10 at 1.3 mm. Heating from the interstellar radiation field may reduce further the flux increase observed at longer wavelengths. We find that during FU Ori-type outbursts the bolometric temperature and luminosity may incorrectly classify a source as a more evolved YSO due to a larger fraction of the radiation of the object being emitted at shorter wavelengths.

scholarly journals Identification of Class I Methanol Masers with Objects of Near and Mid-Infrared Bands and the Third Version of the Class I Methanol Maser (MMI) Catalog

2012 ◽  
Vol 8 (S287) ◽  
pp. 280-281
Author(s):  
Olga Bayandina ◽  
Irina Val'tts ◽  
Grigorii Larionov
Keyword(s):  
Galactic Plane ◽  
Short Wave ◽  
Class I ◽  
Young Stellar Objects ◽  
Bipolar Outflows ◽  
Stellar Objects ◽  
Mid Infrared ◽  
Dark Clouds ◽  
The Third ◽  
Methanol Masers

AbstractAn identification has been conducted of class I methanol masers with 1) short-wave infrared objects EGO (extended green objects) - tracer bipolar outflow of matter in young stellar objects, and 2) isolated pre-protostellar gas-dust cores of the interstellar medium which are observed in absorption in the mid-infrared in the Galactic plane. It is shown that more than 50% of class I methanol masers are identified with bipolar outflows, considering the EGO as bipolar outflows (as compared with the result of 22% in the first version of the MMI catalog that contains no information about EGO). 99 from 139 class I methanol masers (71%) are identified with SDC. Thus, it seems possible that the MMI can be formed in isolated self-gravitating condensations, which are the silhouette of dark clouds - IRDC and SDC.

Gemini Mid-Infrared Imaging of Massive Young Stellar Objects in NGC 3576

2003 ◽  
Vol 126 (5) ◽  
pp. 2411-2420 ◽  
Author(s):  
C. L. Barbosa ◽  
A. Damineli ◽  
R. D. Blum ◽  
P. S. Conti
Keyword(s):  
Infrared Imaging ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Mid Infrared

scholarly journals MID-INFRARED SPECTRAL VARIABILITY ATLAS OF YOUNG STELLAR OBJECTS

2012 ◽  
Vol 201 (2) ◽  
pp. 11 ◽  
Author(s):  
Á. Kóspál ◽  
P. Ábrahám ◽  
J. A. Acosta-Pulido ◽  
C. P. Dullemond ◽  
Th. Henning ◽  
...  
Keyword(s):  
Young Stellar Objects ◽  
Spectral Variability ◽  
Stellar Objects ◽  
Mid Infrared ◽  
Infrared Spectral

scholarly journals Mid-infrared interferometry of massive young stellar objects

2008 ◽  
Vol 131 ◽  
pp. 012024 ◽  
Author(s):  
H Linz ◽  
B Stecklum ◽  
R Follert ◽  
Th Henning ◽  
R van Boekel ◽  
...  
Keyword(s):  
Young Stellar Objects ◽  
Stellar Objects ◽  
Mid Infrared ◽  
Infrared Interferometry
Sign in / Sign up

Export Citation Format

Share Document