Brackett<i>γ</i>radiation from the inner gaseous accretion disk, magnetosphere, and disk wind region of Herbig AeBe stars

Тамбовцева, Л. В.; Гринин, В. П.; Weigelt, G.

doi:10.1051/0004-6361/201628256

Cited by 33 publications

(30 citation statements)

References 70 publications

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“…More likely, the slight size difference between the blue-and red-shifted Brγ line components is due to a compact magnetosphere coexisting with the disk wind emission. As shown in previous interferometric studies, a magnetosphere would only slightly contribute to the total Brγ line intensity, but it would modify the line profile along the wings and increase the continuum-compensated Brγ line visibilities of the red-shifted component Kurosawa et al 2016;Tambovtseva et al 2016). These characteristic features are, indeed, observed in S CrA N: namely the inverse PCygni profile in both He i and Brγ lines, and a smaller size of the red-shifted Brγ line emitting region.…”

Section: Brγ Emission Line In S Cra Nsupporting

confidence: 64%

The wind and the magnetospheric accretion onto the T Tauri star S Coronae Australis at sub-au resolution

Lopez¹,

Perraut²,

Garatti³

et al. 2017

A&A

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Aims. To investigate the inner regions of protoplanetary disks, we performed near-infrared interferometric observations of the classical T Tauri binary system S CrA. Methods. We present the first VLTI-GRAVITY high spectral resolution (R ∼ 4000) observations of a classical T Tauri binary, S CrA (composed of S CrA N and S CrA S and separated by ∼1 . 4), combining the four 8-m telescopes in dual-field mode. Results. Our observations in the near-infrared K-band continuum reveal a disk around each binary component, with similar half-flux radii of about 0.1 au at d∼130 pc, inclinations (i =28±3• and i =22±6 • ), and position angles (PA=0 • ±6• and PA=-2 • ±12• ), suggesting that they formed from the fragmentation of a common disk. The S CrA N spectrum shows bright He i and Brγ line emission exhibiting inverse P-Cygni profiles, typically associated with infalling gas. The continuum-compensated Brγ line visibilities of S CrA N show the presence of a compact Brγ emitting region the radius of which is about ∼0.06 au, which is twice as big as the truncation radius. This component is mostly tracing a wind. Moreover, a slight radius change between the blue-and red-shifted Brγ line components is marginally detected. Conclusions. The presence of an inverse P-Cygni profile in the He i and Brγ lines, along with the tentative detection of a slightly larger size of the blue-shifted Brγ line component, hint at the simultaneous presence of a wind and magnetospheric accretion in S CrA N.

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Section: Brγ Emission Line In S Cra Nsupporting

confidence: 64%

The wind and the magnetospheric accretion onto the T Tauri star S Coronae Australis at sub-au resolution

Lopez¹,

Perraut²,

Garatti³

et al. 2017

A&A

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“…find the line emission region consistent with a rotating disk. Similarly,Tambovtseva et al (2016) andKreplin et al (2018) find the diskwind a more likely explanation for the emitting region than the compact accretion channels. Even higher resolution Hα CHARA data discussed byMendigutía et al (2017) present a similar diversity.…”

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confidence: 84%

The accretion rates and mechanisms of Herbig Ae/Be stars

Wichittanakom

Oudmaijer

Fairlamb

et al. 2020

Monthly Notices of the Royal Astronomical Society

126

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This work presents a spectroscopic study of 163 Herbig Ae/Be stars. Amongst these, we present new data for 30 objects. Stellar parameters such as temperature, reddening, mass, luminosity and age are homogeneously determined. Mass accretion rates are determined from Hα emission line measurements. Our data is complemented with the X-Shooter sample from previous studies and we update results using Gaia DR2 parallaxes giving a total of 78 objects with homogeneously determined stellar parameters and mass accretion rates. In addition, mass accretion rates of an additional 85 HAeBes are determined. We confirm previous findings that the mass accretion rate increases as a function of stellar mass, and the existence of a different slope for lower and higher mass stars respectively. The mass where the slope changes is determined to be 3.98 +1.37 −0.94 M . We discuss this break in the context of different modes of disk accretion for low-and high mass stars. Because of their similarities with T Tauri stars, we identify the accretion mechanism for the late-type Herbig stars with the Magnetospheric Accretion. The possibilities for the earlier-type stars are still open, we suggest the Boundary Layer accretion model may be a viable alternative. Finally, we investigated the mass accretion -age relationship. Even using the superior Gaia based data, it proved hard to select a large enough sub-sample to remove the mass dependency in this relationship. Yet, it would appear that the mass accretion does decline with age as expected from basic theoretical considerations.

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“…Usually, the Brγ line in emission can have different origins: accretion of matter onto the star (Eisner et al 2009;Tambovtseva et al 2014), or ejected material in different manifestations -winds or jets (Weigelt et al 2011;Stecklum et al 2012;Garcia Lopez et al 2015Caratti o Garatti et al 2015b). See also Coffey et al (2010) and Tambovtseva et al (2016) for a detailed discussion of the origin of Brγ emission. Nonetheless, one has to take into account that the broad profile of the H I around the line peak can also be accounted for by the significant contribution expected from the disc rotation motions very close to the base of the jet (v kep ∼ 130 km yr −1 , for M ∼ 20 M and R ∼ 10 R ).…”

Section: Atomic Au-scale Jetmentioning

confidence: 99%

Parsec-scale jets driven by high-mass young stellar objects

Fedriani

Garatti

Coffey

et al. 2018

A&A

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Context. Protostellar jets in high-mass young stellar objects (HMYSOs) play a key role in the understanding of star formation and provide us with an excellent tool to study fundamental properties of HMYSOs. Aims. We aim at studying the physical and kinematic properties of the near-infrared (NIR) jet of IRAS 13481-6124 from au to parsec scales. Methods. Our study includes NIR data from the Very Large Telescope instruments SINFONI, CRIRES, and ISAAC. Information about the source and its immediate environment is retrieved with SINFONI. The technique of spectro-astrometry is performed with CRIRES to study the jet on au scales. The parsec-scale jet and its kinematic and dynamic properties are investigated using ISAAC. Results. The SINFONI spectra in H and K bands are rich in emission lines that are mainly associated with ejection and accretion processes. Spectro-astrometry is applied to the Brγ line, and for the first time, to the Brα line, revealing their jet origin with milliarcsecond-scale photocentre displacements (11−15 au). This allows us to constrain the kinematics of the au-scale jet and to derive its position angle (~216°). ISAAC spectroscopy reveals H2 emission along the parsec-scale jet, which allows us to infer kinematic and dynamic properties of the NIR parsec-scale jet. The mass-loss rate inferred for the NIR jet is Ṁejec ~ 10−4 M⊙ yr−1 and the thrust is Ṗ ~ 10−2 M⊙ yr−1 km s−1, which is roughly constant for the formation history of the young star. A tentative estimate of the ionisation fraction is derived for the massive jet by comparing the radio and NIR mass-loss rates. An ionisation fraction ≲8% is obtained, which means that the bulk of the ejecta is traced by the NIR jet and that the radio jet only delineates a small portion of it.

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Brackettγradiation from the inner gaseous accretion disk, magnetosphere, and disk wind region of Herbig AeBe stars

Cited by 33 publications

References 70 publications

The wind and the magnetospheric accretion onto the T Tauri star S Coronae Australis at sub-au resolution

The wind and the magnetospheric accretion onto the T Tauri star S Coronae Australis at sub-au resolution

The accretion rates and mechanisms of Herbig Ae/Be stars

Parsec-scale jets driven by high-mass young stellar objects

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