Multiwavelength interferometric observations and modeling of circumstellar disks

Schegerer, Alexander; Ratzka, Thorsten; Schuller, P. A.; Wolf, S.; Mosoni, L.; Leinert, Ch.

doi:10.1051/0004-6361/201220190

Cited by 18 publications

(23 citation statements)

References 102 publications

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“…In V1026 Sco, a magnetic field has not been detected (Alecian et al 2013a), which could mean that it is weak, as expected for Herbig Ae stars (Weise et al 2010). Even if a magnetic field exists, but could not be detected, the high value of the stellar rotation velocity of V1026 Sco suggests that rotational braking via disk locking (Koenigl 1991;Stȩpień 2000) is much weaker than in T Tauri stars. PA |PA-ϑ| r Ring in = 1.30 ± 0.14 mas H band …”

Section: Discussionmentioning

confidence: 95%

“…Monnier et al (2005) have performed Keck Interferometer (KI) measurements of V1026 Sco and found an inner disk diameter of 2.52 mas (0.29 AU at 116 pc). In a recent publication, Schegerer et al (2013) have reported mid-and near-infrared (NIR) interferometric observations (archival MIDI/VLTI & IOTA data), and performed radiative transfer modeling of V1026 Sco, and derived a disk structure with a gap from 0.35 AU to 0.80 AU.…”

Section: Introductionmentioning

confidence: 99%

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The inner circumstellar disk of the UX Orionis star V1026 Scorpii

Vural

Kreplin

Kishimoto

et al. 2014

A&A

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Context. The UX Ori type variables (named after the prototype of their class) are intermediate-mass pre-main sequence objects. One of the most likely causes of their variability is the obscuration of the central star by orbiting dust clouds. Aims. We investigate the structure of the circumstellar environment of the UX Ori star V1026 Sco (HD 142666) and test whether the disk inclination is large enough to explain the UX Ori variability. Methods. We observed the object in the low-resolution mode of the near-infrared interferometric VLTI/AMBER instrument and derived H-and K-band visibilities and closure phases. We modeled our AMBER observations, published Keck Interferometer observations, archival MIDI/VLTI visibilities, and the spectral energy distribution using geometric and temperature-gradient models. • approximately agrees with the inclination derived with the geometric model (49 ± 5 • in the K band and 50 ± 11 • in the H band). The position angle of the fitted geometric and temperaturegradient models are 163 ± 9 • (K band; 179 ± 17 • in the H band) and 169.3 +4.2 −6.7• , respectively. Conclusions. The narrow width of the inner ring-shaped model disk and the disk gap might be an indication for a puffed-up inner rim shadowing outer parts of the disk. The intermediate inclination of ∼50 • is consistent with models of UX Ori objects where dust clouds in the inclined disk obscure the central star.

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Section: Discussionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

The inner circumstellar disk of the UX Orionis star V1026 Scorpii

Vural

Kreplin

Kishimoto

et al. 2014

A&A

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“…The inset on the top right shows the observed line profile (black) and the fitted profile (blue). The vertical red line shows the inner edge of the dust disk at ∼ 1 AU as inferred from IR interferometry (Schegerer et al 2013). as the accretion rates are normal and the stellar abundances for these sources close to solar (Kama et al 2015;Banzatti et al 2018). The lower sub-mm intensity implies a lower dust surface density at 1 AU.…”

Section: Inner Disk Co Emission Is Confined By Substructuresmentioning

confidence: 96%

Probing planet formation and disk substructures in the inner disk of Herbig Ae stars with CO rovibrational emission

Bosman

Banzatti

Bruderer

et al. 2019

A&A

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Context. CO rovibrational lines are efficient probes of warm molecular gas and can give unique insights into the inner 10 AU of proto-planetary disks, effectively complementing ALMA observations. Recent studies have found a relation between the ratio of lines originating from the second and first vibrationally excited state, denoted as v2/v1, and the Keplerian velocity or emitting radius of CO. Counterintuitively, in disks around Herbig Ae stars the vibrational excitation is low when CO lines come from close to the star, and high when lines only probe gas at large radii (more than 5 AU). The v2/v1 ratio is also counterintuitively anti-correlated with the near-IR (NIR) excess, which probes hot/warm dust in the inner disk. Aims. We aim to find explanations for the observed trends between CO vibrational ratio, emitting radii, and NIR excess, and identify their implications in terms of the physical and chemical structure of inner disks around Herbig stars. Methods. First, slab model explorations in LTE and non-LTE are used to identify the essential parameter space regions that can produce the observed CO emission. Second, we explore a grid of thermo-chemical models using the DALI code, varying gas-to-dust ratio and inner disk radius. Line flux, line ratios and emitting radii are extracted from the simulated lines in the same way as the observations and directly compared to the data. Results. Broad CO lines with low vibrational ratios are best explained by a warm (400-1300 K) inner disk surface with gas-to-dust ratios below 1000 (N CO < 10 18 cm −2 ); no CO is detected within/at the inner dust rim, due to dissociation at high temperatures. In contrast, explaining the narrow lines with high vibrational ratios requires an inner cavity of a least 5 AU in both dust and gas, followed by a cool (100-300 K) molecular gas reservoir with gas-to-dust ratios greater than 10000 (N CO > 10 18 cm −2 ) at the cavity wall. In all cases the CO gas must be close to thermalization with the dust (T gas ∼ T dust ). Conclusions. The high gas-to-dust ratios needed to explain high v2/v1 in narrow CO lines for a subset of group I disks can naturally be interpreted as due to the dust traps that have been proposed to explain millimeter dust cavities. The dust trap and the low gas surface density inside the cavity are consistent with the presence of one or more massive planets. The difference between group I disks with low and high NIR excess can be explained by gap opening mechanisms that do or do not create an efficient dust trap, respectively. The broad lines seen in most group II objects indicate a very flat disk in addition to inner disk substructures within 10 AU that can be related to the substructures recently observed with ALMA. We provide simulated ELT-METIS images to directly test these scenarios in the future.

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“…For at least two group II disk sources, gaps have already been claimed. Based on near-and mid-infrared interferometric observations (IOTA and MIDI, respectively) Schegerer et al (2013) modeled the disk around HD 142666 as having a gap with a radius of 0.8 au, plus an additional inner disk between 0.3 and 0.35 au. Chen et al (2012), on the other hand, observed and analyzed the disk around HD 144432, and their interferometric observations (AMBER and MIDI) point to a similar model with a gap radius of 1 au and a compact 0.2-au radius inner ring.…”

Section: Overlap In Spatial Properties Group I and Iimentioning

confidence: 99%

The structure of disks around intermediate-mass young stars from mid-infrared interferometry

Boekel

Henning

et al. 2015

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Context. The disks around Herbig Ae/Be stars are commonly divided into group I and group II based on their far-infrared spectral energy distribution, and the common interpretation for that is flared and flat disks. Our understanding of the evolution of these disks is rapidly changing. Recent observations suggest that many flaring disks have gaps, whereas flat disks are thought to be gapless. Aims. The different groups of objects can be expected to have different structural signatures in high-angular-resolution data, related to gaps, dust settling, and flaring. We aim to use such data to gain new insight into disk structure and evolution. Methods. Over the past 10 years, the MIDI instrument on the Very Large Telescope Interferometer has collected observations of several tens of protoplanetary disks. We modeled the large set of observations with simple geometric models and compared the characteristic sizes among the different objects. A population of radiative-transfer models was synthesized for interpreting the midinfrared signatures. Results. Objects with similar luminosities show very different disk sizes in the mid-infrared. This may point to an intrinsic diversity or could also hint at different evolutionary stages of the disks. Restricting this to the young objects of intermediate mass, we confirm that most group I disks are in agreement with being transitional (i.e., they have gaps). We find that several group II objects have mid-infrared sizes and colors that overlap with sources classified as group I, transition disks. This suggests that these sources have gaps, which has been demonstrated for a subset of them. This may point to an intermediate population between gapless and transition disks. Conclusions. Flat disks with gaps are most likely descendants of flat disks without gaps. Potentially related to the formation of massive bodies, gaps may therefore even develop in disks in a far stage of grain growth and settling. The evolutionary implications of this new population could be twofold. Either gapped flat disks form a separate population of evolved disks or some of them may evolve further into flaring disks with large gaps. The latter transformation may be governed by the interaction with a massive planet, carving a large gap and dynamically exciting the grain population in the disk.

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Multiwavelength interferometric observations and modeling of circumstellar disks

Cited by 18 publications

References 102 publications

The inner circumstellar disk of the UX Orionis star V1026 Scorpii

The inner circumstellar disk of the UX Orionis star V1026 Scorpii

Probing planet formation and disk substructures in the inner disk of Herbig Ae stars with CO rovibrational emission

The structure of disks around intermediate-mass young stars from mid-infrared interferometry

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