Mid-infrared interferometric variability of DG Tauri

Implications for the inner-disk structure

J. Varga, K. E. Gabányi, P. Ábrahám, L. Chen, A. Kóspál, J. Menu, Th Ratzka, R. Van Boekel, C. P. Dullemond, Th Henning, W. Jaffe, A. Juhász, A. Moór, L. Mosoni, N. Sipos

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

DG Tau is a low-mass pre-main sequence star, whose strongly accreting protoplanetary disk exhibits a so-far enigmatic behavior: Its mid-infrared thermal emission is strongly time-variable, even turning the 10 μm silicate feature from emission to absorption temporarily. Aims. We look for the reason for the spectral variability at high spatial resolution and at multiple epochs. Methods. Infrared interferometry can spatially resolve the thermal emission of the circumstellar disk, also giving information about dust processing. We study the temporal variability of the mid-infrared interferometric signal, observed with the VLTI/MIDI instrument at six epochs between 2011 and 2014. We fit a geometric disk model to the observed interferometric signal to obtain spatial information about the disk. We also model the mid-infrared spectra by template fitting to characterize the profile and time dependence of the silicate emission. We use physically motivated radiative transfer modeling to interpret the mid-infrared interferometric spectra. Results. The inner disk (r < 1-3 au) spectra exhibit a 10 μm absorption feature related to amorphous silicate grains. The outer disk (r > 1-3 au) spectra show a crystalline silicate feature in emission, similar to the spectra of comet Hale-Bopp. The striking difference between the inner and outer disk spectral feature is highly unusual among T Tauri stars. The mid-infrared variability is dominated by the outer disk. The strength of the silicate feature changed by more than a factor of two. Between 2011 and 2014 the half-light radius of the mid-infrared-emitting region decreased from 1.15 to 0.7 au. Conclusions. For the origin of the absorption we discuss four possible explanations: A cold obscuring envelope, an accretion heated inner disk, a temperature inversion on the disk surface and a misaligned inner geometry. The silicate emission in the outer disk can be explained by dusty material high above the disk plane, whose mass can change with time, possibly due to turbulence in the disk.

Original languageEnglish
Article numberA84
JournalAstronomy and Astrophysics
Volume604
DOIs
Publication statusPublished - Aug 1 2017

Fingerprint

silicate
silicates
Hale-Bopp
temperature inversion
thermal emission
interferometry
comet
radiative transfer
infrared spectra
time measurement
spatial resolution
Hale-Bopp comet
turbulence
accretion
temperature inversions
pre-main sequence stars
dust
protoplanetary disks
T Tauri stars
geometry

Keywords

  • Infrared: Stars
  • Protoplanetary disks
  • Stars: Individual: DG Tau
  • Stars: Pre-main sequence
  • Techniques: Interferometric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Varga, J., Gabányi, K. E., Ábrahám, P., Chen, L., Kóspál, A., Menu, J., ... Sipos, N. (2017). Mid-infrared interferometric variability of DG Tauri: Implications for the inner-disk structure. Astronomy and Astrophysics, 604, [A84]. https://doi.org/10.1051/0004-6361/201630287

Mid-infrared interferometric variability of DG Tauri : Implications for the inner-disk structure. / Varga, J.; Gabányi, K. E.; Ábrahám, P.; Chen, L.; Kóspál, A.; Menu, J.; Ratzka, Th; Van Boekel, R.; Dullemond, C. P.; Henning, Th; Jaffe, W.; Juhász, A.; Moór, A.; Mosoni, L.; Sipos, N.

In: Astronomy and Astrophysics, Vol. 604, A84, 01.08.2017.

Research output: Contribution to journalArticle

Varga, J, Gabányi, KE, Ábrahám, P, Chen, L, Kóspál, A, Menu, J, Ratzka, T, Van Boekel, R, Dullemond, CP, Henning, T, Jaffe, W, Juhász, A, Moór, A, Mosoni, L & Sipos, N 2017, 'Mid-infrared interferometric variability of DG Tauri: Implications for the inner-disk structure', Astronomy and Astrophysics, vol. 604, A84. https://doi.org/10.1051/0004-6361/201630287
Varga, J. ; Gabányi, K. E. ; Ábrahám, P. ; Chen, L. ; Kóspál, A. ; Menu, J. ; Ratzka, Th ; Van Boekel, R. ; Dullemond, C. P. ; Henning, Th ; Jaffe, W. ; Juhász, A. ; Moór, A. ; Mosoni, L. ; Sipos, N. / Mid-infrared interferometric variability of DG Tauri : Implications for the inner-disk structure. In: Astronomy and Astrophysics. 2017 ; Vol. 604.
@article{0a432d3cfe8240b8bf031d58ee71826a,
title = "Mid-infrared interferometric variability of DG Tauri: Implications for the inner-disk structure",
abstract = "DG Tau is a low-mass pre-main sequence star, whose strongly accreting protoplanetary disk exhibits a so-far enigmatic behavior: Its mid-infrared thermal emission is strongly time-variable, even turning the 10 μm silicate feature from emission to absorption temporarily. Aims. We look for the reason for the spectral variability at high spatial resolution and at multiple epochs. Methods. Infrared interferometry can spatially resolve the thermal emission of the circumstellar disk, also giving information about dust processing. We study the temporal variability of the mid-infrared interferometric signal, observed with the VLTI/MIDI instrument at six epochs between 2011 and 2014. We fit a geometric disk model to the observed interferometric signal to obtain spatial information about the disk. We also model the mid-infrared spectra by template fitting to characterize the profile and time dependence of the silicate emission. We use physically motivated radiative transfer modeling to interpret the mid-infrared interferometric spectra. Results. The inner disk (r < 1-3 au) spectra exhibit a 10 μm absorption feature related to amorphous silicate grains. The outer disk (r > 1-3 au) spectra show a crystalline silicate feature in emission, similar to the spectra of comet Hale-Bopp. The striking difference between the inner and outer disk spectral feature is highly unusual among T Tauri stars. The mid-infrared variability is dominated by the outer disk. The strength of the silicate feature changed by more than a factor of two. Between 2011 and 2014 the half-light radius of the mid-infrared-emitting region decreased from 1.15 to 0.7 au. Conclusions. For the origin of the absorption we discuss four possible explanations: A cold obscuring envelope, an accretion heated inner disk, a temperature inversion on the disk surface and a misaligned inner geometry. The silicate emission in the outer disk can be explained by dusty material high above the disk plane, whose mass can change with time, possibly due to turbulence in the disk.",
keywords = "Infrared: Stars, Protoplanetary disks, Stars: Individual: DG Tau, Stars: Pre-main sequence, Techniques: Interferometric",
author = "J. Varga and Gab{\'a}nyi, {K. E.} and P. {\'A}brah{\'a}m and L. Chen and A. K{\'o}sp{\'a}l and J. Menu and Th Ratzka and {Van Boekel}, R. and Dullemond, {C. P.} and Th Henning and W. Jaffe and A. Juh{\'a}sz and A. Mo{\'o}r and L. Mosoni and N. Sipos",
year = "2017",
month = "8",
day = "1",
doi = "10.1051/0004-6361/201630287",
language = "English",
volume = "604",
journal = "Astronomy and Astrophysics",
issn = "0004-6361",
publisher = "EDP Sciences",

}

TY - JOUR

T1 - Mid-infrared interferometric variability of DG Tauri

T2 - Implications for the inner-disk structure

AU - Varga, J.

AU - Gabányi, K. E.

AU - Ábrahám, P.

AU - Chen, L.

AU - Kóspál, A.

AU - Menu, J.

AU - Ratzka, Th

AU - Van Boekel, R.

AU - Dullemond, C. P.

AU - Henning, Th

AU - Jaffe, W.

AU - Juhász, A.

AU - Moór, A.

AU - Mosoni, L.

AU - Sipos, N.

PY - 2017/8/1

Y1 - 2017/8/1

N2 - DG Tau is a low-mass pre-main sequence star, whose strongly accreting protoplanetary disk exhibits a so-far enigmatic behavior: Its mid-infrared thermal emission is strongly time-variable, even turning the 10 μm silicate feature from emission to absorption temporarily. Aims. We look for the reason for the spectral variability at high spatial resolution and at multiple epochs. Methods. Infrared interferometry can spatially resolve the thermal emission of the circumstellar disk, also giving information about dust processing. We study the temporal variability of the mid-infrared interferometric signal, observed with the VLTI/MIDI instrument at six epochs between 2011 and 2014. We fit a geometric disk model to the observed interferometric signal to obtain spatial information about the disk. We also model the mid-infrared spectra by template fitting to characterize the profile and time dependence of the silicate emission. We use physically motivated radiative transfer modeling to interpret the mid-infrared interferometric spectra. Results. The inner disk (r < 1-3 au) spectra exhibit a 10 μm absorption feature related to amorphous silicate grains. The outer disk (r > 1-3 au) spectra show a crystalline silicate feature in emission, similar to the spectra of comet Hale-Bopp. The striking difference between the inner and outer disk spectral feature is highly unusual among T Tauri stars. The mid-infrared variability is dominated by the outer disk. The strength of the silicate feature changed by more than a factor of two. Between 2011 and 2014 the half-light radius of the mid-infrared-emitting region decreased from 1.15 to 0.7 au. Conclusions. For the origin of the absorption we discuss four possible explanations: A cold obscuring envelope, an accretion heated inner disk, a temperature inversion on the disk surface and a misaligned inner geometry. The silicate emission in the outer disk can be explained by dusty material high above the disk plane, whose mass can change with time, possibly due to turbulence in the disk.

AB - DG Tau is a low-mass pre-main sequence star, whose strongly accreting protoplanetary disk exhibits a so-far enigmatic behavior: Its mid-infrared thermal emission is strongly time-variable, even turning the 10 μm silicate feature from emission to absorption temporarily. Aims. We look for the reason for the spectral variability at high spatial resolution and at multiple epochs. Methods. Infrared interferometry can spatially resolve the thermal emission of the circumstellar disk, also giving information about dust processing. We study the temporal variability of the mid-infrared interferometric signal, observed with the VLTI/MIDI instrument at six epochs between 2011 and 2014. We fit a geometric disk model to the observed interferometric signal to obtain spatial information about the disk. We also model the mid-infrared spectra by template fitting to characterize the profile and time dependence of the silicate emission. We use physically motivated radiative transfer modeling to interpret the mid-infrared interferometric spectra. Results. The inner disk (r < 1-3 au) spectra exhibit a 10 μm absorption feature related to amorphous silicate grains. The outer disk (r > 1-3 au) spectra show a crystalline silicate feature in emission, similar to the spectra of comet Hale-Bopp. The striking difference between the inner and outer disk spectral feature is highly unusual among T Tauri stars. The mid-infrared variability is dominated by the outer disk. The strength of the silicate feature changed by more than a factor of two. Between 2011 and 2014 the half-light radius of the mid-infrared-emitting region decreased from 1.15 to 0.7 au. Conclusions. For the origin of the absorption we discuss four possible explanations: A cold obscuring envelope, an accretion heated inner disk, a temperature inversion on the disk surface and a misaligned inner geometry. The silicate emission in the outer disk can be explained by dusty material high above the disk plane, whose mass can change with time, possibly due to turbulence in the disk.

KW - Infrared: Stars

KW - Protoplanetary disks

KW - Stars: Individual: DG Tau

KW - Stars: Pre-main sequence

KW - Techniques: Interferometric

UR - http://www.scopus.com/inward/record.url?scp=85027341959&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85027341959&partnerID=8YFLogxK

U2 - 10.1051/0004-6361/201630287

DO - 10.1051/0004-6361/201630287

M3 - Article

VL - 604

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

SN - 0004-6361

M1 - A84

ER -