Evidence for a hot dust-free inner disk around 51 Oph

Thi, W. F.; Dalen, B van; Bik, Arjan; Waters, L.B.F.M.

doi:10.1051/0004-6361:200400132

Cited by 40 publications

(38 citation statements)

References 26 publications

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“…The final reduced χ 2 r is 0.7. A81, page 3 of 4 A&A 579, A81 (2015) The inclination angle found for the gaseous disk in our study is compatible with the previous estimate of Thi et al (2005), that is, 88…”

Section: Kinematic Modelsupporting

confidence: 89%

The peculiar fast-rotating star 51 Ophiuchi probed by VEGA/CHARA

Jamialahmadi

Bério

Meilland

et al. 2015

A&A

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Context. Stellar rotation is a key in our understanding of both mass-loss and evolution of intermediate and massive stars. It can lead to anisotropic mass-loss in the form of radiative wind or an excretion disk. Aims. We wished to spatially resolve the photosphere and gaseous environment of 51 Oph, a peculiar star with a very high v sin i of 267 km s −1 and an evolutionary status that remains unsettled. It has been classified by different authors as a Herbig, a β Pic, or a classical Be star. Methods. We used the VEGA visible beam combiner installed on the CHARA array that reaches a submilliarcsecond resolution. Observation were centered on the Hα emission line. Results. We derived, for the first time, the extension and flattening of 51 Oph photosphere. We found a major axis of θ eq = 8.08 ± 0.70 R and a minor axis of θ pol = 5.66 ± 0.23 R . This high photosphere distortion shows that the star is rotating close to its critical velocity. Finally, using spectro-interferometric measurements in the Hα line, we constrained the circumstellar environment geometry and kinematics and showed that the emission is produced in a 5.2 ± 2 R disk in Keplerian rotation. Conclusions. From the visible point of view, 51 Oph presents all the features of a classical Be star: near critical-rotation and doublepeaked Hα line in emission produced in a gaseous disk in Keplerian rotation. However, this does not explain the presence of dust as seen in the mid-infrared and millimeter spectra, and the evolutionary status of 51 Oph remains unsettled.

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Section: Kinematic Modelsupporting

confidence: 89%

The peculiar fast-rotating star 51 Ophiuchi probed by VEGA/CHARA

Jamialahmadi

Bério

Meilland

et al. 2015

A&A

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“…The CO molecule could survive from the photodissociation even in the dust-free inner gas disk. As argued by Thi et al (2005), the CO column density of the bestfit model for CO bandhead emission, which originates from dust-free inner hot disk, is higher than the value required to be self-shielded (N(CO) ∼ 10 15 cm −2 , van Dishoeck & Black 1988). In addition, a high CO formation rate (C + OH  CO + H) at the high gas density and temperature could replenish the CO molecules.…”

Section: Discussionmentioning

confidence: 95%

Igrins Spectroscopy of Class I Sources: Iras 03445+3242 and Iras 04239+2436

Lee

Park

et al. 2016

ApJ

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We have detected molecular and atomic line emission from the hot and warm disks of two Class I sources, IRAS 03445+3242 and IRAS 04239+2436, using the high-resolution Immersion GRating INfrared Spectrograph (IGRINS). CO overtone band transitions and near-IR lines of Na I and Ca I, all in emission, trace the hot inner disk, while CO rovibrational absorption spectra of the first overtone transition trace the warm gas within the inner few AU of the disk. The emission-line profiles for both sources show evidence for Keplerian disks. A thin Keplerian disk with power-law temperature and column density profiles with a projected rotational velocity of ∼60-75 km s −1 and a gas temperature of ∼3500 K at the innermost annulus can reproduce the CO overtone band emission. Na I and Ca I emission lines also arise from this disk, but they show complicated line features possibly affected by photospheric absorption lines. Multi-epoch observations show asymmetric variations of the line profiles on one-year (CO overtone bandhead and atomic lines for IRAS 03445+3242) or on one-day (atomic lines for IRAS 04239+2436) timescales, implying non-axisymmetric features in disks. The narrow CO rovibrational absorption spectra (v = 0  2) indicate that both warm (>150 K) and cold (∼20-30 K) CO gas are present along the line of sight to the inner disk. This study demonstrates the power of IGRINS as a tool for studies of the sub-AU-scale hot and AU-scale warm protoplanetary disks with its simultaneous coverage of the full H and K bands with high spectral resolution (R = 45,000) allowing many aspects of the sources to be investigated at once.

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“…The CO overtone bandheads are made up of numerous lines tracing rovibrational transitions with ∆v = 2. Overtone transitions are rare compared to the occurrence rate of Brγ emission, but are found toward a number of young stars (Carr 1989;Najita et al 1996aNajita et al , 2000Najita et al , 2007Najita et al , 2009Biscaya et al 1997;Thi et al 2005;Brittain et al 2007;Berthoud et al 2007;Berthoud 2008;Eisner et al 2013). …”

Section: Introductionmentioning

confidence: 99%

Constraining the sub-au-scale distribution of hydrogen and carbon monoxide gas around young stars with the Keck Interferometer

Eisner

Hillenbrand

Stone

2014

Monthly Notices of the Royal Astronomical Society

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We present Keck Interferometer observations of T Tauri and Herbig Ae/Be stars with a spatial resolution of a few milliarcseconds and a spectral resolution of ∼ 2000. Our observations span the K-band, and include the Brγ transition of Hydrogen and the v = 2 → 0 and v = 3 → 1 transitions of carbon monoxide. For several targets we also present data from Keck/NIRSPEC that provide higher spectral resolution, but a seeing-limited spatial resolution, of the same spectral features. We analyze the Brγ emission in the context of both disk and infall/outflow models, and conclude that the Brγ emission traces gas at very small stellocentric radii, consistent with the magnetospheric scale. However some Brγ-emitting gas also seems to be located at radii of 0.1 AU, perhaps tracing the inner regions of magnetically launched outflows. CO emission is detected from several objects, and we generate disk models that reproduce both the KI and NIRSPEC data well. We infer the CO spatial distribution to be coincident with the distribution of continuum emission in most cases. Furthermore the Brγ emission in these objects is roughly coincident with both the CO and continuum emission. We present potential explanations for the spatial coincidence of continuum, Brγ, and CO overtone emission, and explore the implications for the low occurrence rate of CO overtone emission in young stars. Finally, we provide additional discussion of V1685 Cyg, which is unusual among our sample in showing large differences in emitting region size and spatial position as a function of wavelength.

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Evidence for a hot dust-free inner disk around 51 Oph

Cited by 40 publications

References 26 publications

The peculiar fast-rotating star 51 Ophiuchi probed by VEGA/CHARA

The peculiar fast-rotating star 51 Ophiuchi probed by VEGA/CHARA

Igrins Spectroscopy of Class I Sources: Iras 03445+3242 and Iras 04239+2436

Constraining the sub-au-scale distribution of hydrogen and carbon monoxide gas around young stars with the Keck Interferometer

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