Star–Disk Interactions in Multiband Photometric Monitoring of the Classical T Tauri Star GI Tau

Guo, Zhen; Herczeg, Gregory J.; Jose, Jessy; Fu, Jian-Ning; Chiang, P. S.; Grankin, K. N.; Michel, R.; Yadav, R. K. S.; Liu, Jinzhong; Chen, Wen-Ping; Li, Gang; Xue, Hui-Fang; Niu, Hubiao; Subramaniam, Annapurni; Sharma, Saurabh; Prasert, N.; Flores-Fajardo, N.; Castro, A.; Altamirano-Dévora, Liliana

doi:10.3847/1538-4357/aa9e52

Cited by 31 publications

(21 citation statements)

References 123 publications

(223 reference statements)

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“…The median SED has been reddened with the extinction of each source, and then normalized to the J-band flux. Rodriguez et al 2015 for V409 Tau andGuo et al 2018 for GI Tau). V409 Tau, which sports the largest difference (0.37 dex), has been also observed with SDSS (Ahn et al 2012) and is 11.934 mag in SDSS − i band.…”

Section: B Flux Calibrationmentioning

confidence: 97%

A New Look at T Tauri Star Forbidden Lines: MHD-driven Winds from the Inner Disk

Fang

Pascucci

Edwards

et al. 2018

ApJ

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150

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Magnetohydrodynamic (MHD) and photoevaporative winds are thought to play an important role in the evolution and dispersal of planet-forming disks. We report the first high-resolution (∆v ∼ 6 km s −1 ) analysis of [S II] λ4068, [O I] λ5577, and [O I] λ6300 lines from a sample of 48 T Tauri stars. Following Simon et al. (2016), we decompose them into three kinematic components: a high-velocity component (HVC) associated with jets, and a low-velocity narrow (LVC-NC) and broad (LVC-BC) components. We confirm previous findings that many LVCs are blueshifted by more than 1.5 km s −1 thus most likely trace a slow disk wind. We further show that the profiles of individual components are similar in the three lines. We find that most LVC-BC and NC line ratios are explained by thermally excited gas with temperatures between 5,000−10,000 K and electron densities ∼ 10 7 − 10 8 cm −3 . The HVC ratios are better reproduced by shock models with a pre-shock H number density of ∼ 10 6 − 10 7 cm −3 . Using these physical properties, we estimateṀ wind /Ṁ acc for the LVC andṀ jet /Ṁ acc for the HVC. In agreement with previous work, the mass carried out in jets is modest compared to the accretion rate. With the likely assumption that the NC wind height is larger than the BC, the LVC-BCṀ wind /Ṁ acc is found to be higher than the LVC-NC. These results suggest that most of the mass loss occurs close to the central star, within a few au, through an MHD driven wind. Depending on the wind height, MHD winds might play a major role in the evolution of the disk mass.

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Section: B Flux Calibrationmentioning

confidence: 97%

A New Look at T Tauri Star Forbidden Lines: MHD-driven Winds from the Inner Disk

Fang

Pascucci

Edwards

et al. 2018

ApJ

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150

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“…There is no clear periodicity in these changes judging from our long-term photometric monitoring, and large changes can occur over days as well as over weeks. Variations due to extinction events are not unusual among the TTSs (e.g., Herbst et al 1994;Guo et al 2018, and references therein).…”

Section: Photometrymentioning

confidence: 99%

S Coronae Australis: a T Tauri twin

Gahm

Петров

Tambovsteva

et al. 2018

A&A

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Context. The star S CrA is a tight visual binary consisting of two classical T Tauri stars. Both components are outstanding regarding their spectral characteristics and brightness variations. Aims. Our aim is to explore the extraordinary spectral features seen in these stars, derive stellar parameters, define spectral signatures of accreting gas and winds, estimate the inclinations of the disks, and to match numerical models with observed properties. Methods. High-resolution spectra were collected of each component over several nights at the European Southern Observatory (ESO) combined with photometric observations covering several years in UBVRI with the SMARTS telescope. The models developed include magnetospheric accretion and a disk wind.Results. Both stars undergo large variation in brightness, ≥ 2 mag in V band. The variations are caused mainly by variable foreground extinction from small-size dust grains, which may be carried along with the accreting gas. The photospheric absorption lines are washed out by superimposed continuous and line emission, and this veiling becomes occasionally exceptionally high. Nevertheless, we extracted the stellar spectra and found that both stars are very similar with regard to stellar parameters (T ef f , log g, v sin i, mass, radius, luminosity). The rotational periods, inferred from velocity shifts in lines originating in surface areas off-set from the pole, are also similar. Combined with the v sin i:s related inclinations were obtained, which agree well with those derived from our model simulations of Balmer line profiles: ∼ 65 • for both stars. At this orientation the trajectories of infalling gas just above the stellar surfaces are parallel to the line-of-sight, and accordingly we observe extended red-shifted absorption components extending to + 380 km s −1 , the estimated free-fall velocity at the surface. Rates of accretion and mass loss were obtained from the models.Conclusions. The two stars are remarkably similar, and S CrA can be regarded as a T Tauri twin. The components differ, however, in terms of degree of veiling and emission line profiles. We have found a good match between observed signatures of accreting gas, wind features, and rotational velocities with those resulting from our modelling for inclinations of ∼ 65 • . These inclinations differ from those derived from interferometric near-infrared (NIR) spectroscopy, and possible causes for this puzzling discrepancy are discussed.

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“…Instead, the behavior resembles that of "faders" in which a warp or disruption in the circumstellar disk at a significant distance from the star creates a long-duration occultation (e.g., Hamilton et al 2001;Bouvier et al 2013). One example around GI Tau has a similar duration and recovery behavior to that in source 283 (Guo et al 2018). Faders can have peculiar and relatively flat extinction variations with color (e.g., Rodriguez et al 2016).…”

Section: Large Variations Of Neutral Color: Occultation By the Circummentioning

confidence: 99%

Near-infrared Variability of Low-mass Stars in IC 1396A and Tr 37

Meng

Rieke

Kim

et al. 2019

ApJ

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We have monitored nearly a square degree in IC 1396A/Tr 37 over 21 epochs extending over 2014-2016 for sources variable in the JHK bands. In our data, 65%±8% of previously identified cluster members show variations, compared with 0.3% of field stars. We identify 119 members of Tr 37 on the basis of variability, forming an unbiased sample down to the brown dwarf regime. The K-band luminosity function in Tr 37 is similar to that of IC 348 but shifted to somewhat brighter values, implying that the K-and M-type members of Tr 37 are younger than those in IC 348. We introduce methods to classify the causes of variability, based on behavior in the color-color and color-magnitude diagrams. Accretion hot spots cause larger variations at J than at K with substantial scatter in the diagrams; there are at least a dozen, with the most active resembling EXors. Eleven sources are probably dominated by intervention of dust clumps in their circumstellar disks, with color behavior indicating the presence of grains larger than for interstellar dust, presumably due to grain growth in their disks. Thirteen sources have larger variations at K than at J or H. For 11 of them, the temperature fitted to the variable component is very close to 2000 K, suggesting that the changes in output are caused by turbulence at the inner rim of the circumstellar disk exposing previously protected populations of grains.

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Star–Disk Interactions in Multiband Photometric Monitoring of the Classical T Tauri Star GI Tau

Cited by 31 publications

References 123 publications

A New Look at T Tauri Star Forbidden Lines: MHD-driven Winds from the Inner Disk

A New Look at T Tauri Star Forbidden Lines: MHD-driven Winds from the Inner Disk

S Coronae Australis: a T Tauri twin

Near-infrared Variability of Low-mass Stars in IC 1396A and Tr 37

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