New view of the corona of classical T Tauri stars: Effects of flaring activity in circumstellar disks

Rosaria Bonito, Costanza Argiroffi, Salvatore Colombo, Fabio Reale, Giovanni Peres, Ibgui, Colombo, Argiroffi, Stehlé, Fabio Reale, Orlando, Giovanni Peres, Bonito

Risultato della ricerca: Article

1 Citazione (Scopus)

Abstract

Context. Classical T Tauri stars (CTTSs) are young low-mass stellar objects that accrete mass from their circumstellar disks. They are characterized by high levels of coronal activity, as revealed by X-ray observations. This activity may affect the disk stability and the circumstellar environment.Aims. Here we investigate if an intense coronal activity due to flares that occur close to the accretion disk may perturb the stability of the inner disk, disrupt the inner part of the disk, and might even trigger accretion phenomena with rates comparable with those observed.Methods. We modeled a magnetized protostar surrounded by an accretion disk through 3D magnetohydrodinamic simulations. The model takes into account the gravity from the central star, the effects of viscosity in the disk, the thermal conduction (including the effects of heat flux saturation), the radiative losses from optically thin plasma, and a parameterized heating function to trigger the flares. We explored cases characterized by a dipole plus an octupole stellar magnetic field configuration and different density of the disk or by different levels of flaring activity.Results. As a result of the simulated intense flaring activity, we observe the formation of several loops that link the star to the disk; all these loops build up a hot extended corona with an X-ray luminosity comparable with typical values observed in CTTSs. The intense flaring activity close to the disk can strongly perturb the disk stability. The flares trigger overpressure waves that travel through the disk and modify its configuration. Accretion funnels may be triggered by the flaring activity and thus contribute to the mass accretion rate of the star. Accretion rates synthesized from the simulations are in a range between 10(-10) and 10(-9) M-circle dot yr(-1). The accretion columns can be perturbed by the flares, and they can interact with each other; they might merge into larger streams. As a result, the accretion pattern can be rather complex: the streams are highly inhomogeneous, with a complex density structure, and clumped.
Lingua originaleEnglish
pagine (da-a)A50-
Numero di pagine12
RivistaASTRONOMY & ASTROPHYSICS
Volume624
Stato di pubblicazionePublished - 2019

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T Tauri stars
coronas
corona
accretion
flares
actuators
stars
accretion disks
flaring
effect
stellar magnetic fields
overpressure
funnels
magnetic field configurations
protostars
simulation
heat flux
viscosity
travel
saturation

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cita questo

New view of the corona of classical T Tauri stars: Effects of flaring activity in circumstellar disks. / Bonito, Rosaria; Argiroffi, Costanza; Colombo, Salvatore; Reale, Fabio; Peres, Giovanni; Ibgui; Colombo; Argiroffi; Stehlé; Reale, Fabio; Orlando; Peres, Giovanni; Bonito.

In: ASTRONOMY & ASTROPHYSICS, Vol. 624, 2019, pag. A50-.

Risultato della ricerca: Article

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title = "New view of the corona of classical T Tauri stars: Effects of flaring activity in circumstellar disks",
abstract = "Context. Classical T Tauri stars (CTTSs) are young low-mass stellar objects that accrete mass from their circumstellar disks. They are characterized by high levels of coronal activity, as revealed by X-ray observations. This activity may affect the disk stability and the circumstellar environment.Aims. Here we investigate if an intense coronal activity due to flares that occur close to the accretion disk may perturb the stability of the inner disk, disrupt the inner part of the disk, and might even trigger accretion phenomena with rates comparable with those observed.Methods. We modeled a magnetized protostar surrounded by an accretion disk through 3D magnetohydrodinamic simulations. The model takes into account the gravity from the central star, the effects of viscosity in the disk, the thermal conduction (including the effects of heat flux saturation), the radiative losses from optically thin plasma, and a parameterized heating function to trigger the flares. We explored cases characterized by a dipole plus an octupole stellar magnetic field configuration and different density of the disk or by different levels of flaring activity.Results. As a result of the simulated intense flaring activity, we observe the formation of several loops that link the star to the disk; all these loops build up a hot extended corona with an X-ray luminosity comparable with typical values observed in CTTSs. The intense flaring activity close to the disk can strongly perturb the disk stability. The flares trigger overpressure waves that travel through the disk and modify its configuration. Accretion funnels may be triggered by the flaring activity and thus contribute to the mass accretion rate of the star. Accretion rates synthesized from the simulations are in a range between 10(-10) and 10(-9) M-circle dot yr(-1). The accretion columns can be perturbed by the flares, and they can interact with each other; they might merge into larger streams. As a result, the accretion pattern can be rather complex: the streams are highly inhomogeneous, with a complex density structure, and clumped.",
keywords = "accretion, accretion disks; magnetohydrodynamics (MHD); stars: coronae; stars: flare; stars: pre-main sequence; X-rays: stars",
author = "Rosaria Bonito and Costanza Argiroffi and Salvatore Colombo and Fabio Reale and Giovanni Peres and Ibgui and Colombo and Argiroffi and Stehl{\'e} and Fabio Reale and Orlando and Giovanni Peres and Bonito",
year = "2019",
language = "English",
volume = "624",
pages = "A50--",
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TY - JOUR

T1 - New view of the corona of classical T Tauri stars: Effects of flaring activity in circumstellar disks

AU - Bonito, Rosaria

AU - Argiroffi, Costanza

AU - Colombo, Salvatore

AU - Reale, Fabio

AU - Peres, Giovanni

AU - Ibgui, null

AU - Colombo, null

AU - Argiroffi, null

AU - Stehlé, null

AU - Reale, Fabio

AU - Orlando, null

AU - Peres, Giovanni

AU - Bonito, null

PY - 2019

Y1 - 2019

N2 - Context. Classical T Tauri stars (CTTSs) are young low-mass stellar objects that accrete mass from their circumstellar disks. They are characterized by high levels of coronal activity, as revealed by X-ray observations. This activity may affect the disk stability and the circumstellar environment.Aims. Here we investigate if an intense coronal activity due to flares that occur close to the accretion disk may perturb the stability of the inner disk, disrupt the inner part of the disk, and might even trigger accretion phenomena with rates comparable with those observed.Methods. We modeled a magnetized protostar surrounded by an accretion disk through 3D magnetohydrodinamic simulations. The model takes into account the gravity from the central star, the effects of viscosity in the disk, the thermal conduction (including the effects of heat flux saturation), the radiative losses from optically thin plasma, and a parameterized heating function to trigger the flares. We explored cases characterized by a dipole plus an octupole stellar magnetic field configuration and different density of the disk or by different levels of flaring activity.Results. As a result of the simulated intense flaring activity, we observe the formation of several loops that link the star to the disk; all these loops build up a hot extended corona with an X-ray luminosity comparable with typical values observed in CTTSs. The intense flaring activity close to the disk can strongly perturb the disk stability. The flares trigger overpressure waves that travel through the disk and modify its configuration. Accretion funnels may be triggered by the flaring activity and thus contribute to the mass accretion rate of the star. Accretion rates synthesized from the simulations are in a range between 10(-10) and 10(-9) M-circle dot yr(-1). The accretion columns can be perturbed by the flares, and they can interact with each other; they might merge into larger streams. As a result, the accretion pattern can be rather complex: the streams are highly inhomogeneous, with a complex density structure, and clumped.

AB - Context. Classical T Tauri stars (CTTSs) are young low-mass stellar objects that accrete mass from their circumstellar disks. They are characterized by high levels of coronal activity, as revealed by X-ray observations. This activity may affect the disk stability and the circumstellar environment.Aims. Here we investigate if an intense coronal activity due to flares that occur close to the accretion disk may perturb the stability of the inner disk, disrupt the inner part of the disk, and might even trigger accretion phenomena with rates comparable with those observed.Methods. We modeled a magnetized protostar surrounded by an accretion disk through 3D magnetohydrodinamic simulations. The model takes into account the gravity from the central star, the effects of viscosity in the disk, the thermal conduction (including the effects of heat flux saturation), the radiative losses from optically thin plasma, and a parameterized heating function to trigger the flares. We explored cases characterized by a dipole plus an octupole stellar magnetic field configuration and different density of the disk or by different levels of flaring activity.Results. As a result of the simulated intense flaring activity, we observe the formation of several loops that link the star to the disk; all these loops build up a hot extended corona with an X-ray luminosity comparable with typical values observed in CTTSs. The intense flaring activity close to the disk can strongly perturb the disk stability. The flares trigger overpressure waves that travel through the disk and modify its configuration. Accretion funnels may be triggered by the flaring activity and thus contribute to the mass accretion rate of the star. Accretion rates synthesized from the simulations are in a range between 10(-10) and 10(-9) M-circle dot yr(-1). The accretion columns can be perturbed by the flares, and they can interact with each other; they might merge into larger streams. As a result, the accretion pattern can be rather complex: the streams are highly inhomogeneous, with a complex density structure, and clumped.

KW - accretion

KW - accretion disks; magnetohydrodynamics (MHD); stars: coronae; stars: flare; stars: pre-main sequence; X-rays: stars

UR - http://hdl.handle.net/10447/359279

UR - https://www.aanda.org/articles/aa/abs/2019/04/aa34342-18/aa34342-18.html

M3 - Article

VL - 624

SP - A50-

JO - ASTRONOMY & ASTROPHYSICS

JF - ASTRONOMY & ASTROPHYSICS

SN - 0004-6361

ER -