Grain growth in the inner regions of Herbig Ae/Be 
star disks

Boekel, R.J.H.M. van; Waters, L.B.F.M.; Dominik, C.; Bouwman, J.; Koter, A. de; Dullemond, C. P.; Paresce, Francesco

doi:10.1051/0004-6361:20030141

Cited by 157 publications

(142 citation statements)

References 9 publications

(7 reference statements)

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“…The latter authors also suggest that UX Ori stars have self-shadowed disks. Consistently, the scheme of van Boekel et al (2003) classifies the star as a group II source. The DDN fit plotted in Fig.…”

Section: Hd 142527mentioning

confidence: 92%

Mid-infrared sizes of circumstellar disks around Herbig Ae/Be stars measured with MIDI on the VLTI

Leinert¹,

Boekel²,

Waters

et al. 2004

A&A

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177

179

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Abstract. We present the first long baseline mid-infrared interferometric observations of the circumstellar disks surrounding Herbig Ae/Be stars. The observations were obtained using the mid-infrared interferometric instrument MIDI at the European Southern Observatory (ESO) Very Large Telescope Interferometer VLTI on Cerro Paranal. The 102 m baseline given by the telescopes UT1 and UT3 was employed, which provides a maximum full spatial resolution of 20 milli-arcsec (mas) at a wavelength of 10 µm. The interferometric signal was spectrally dispersed at a resolution of 30, giving spectrally resolved visibility information from 8 µm to 13.5 µm. We observed seven nearby Herbig Ae/Be stars and resolved all objects. The warm dust disk of HD 100546 could even be resolved in single-telescope imaging. Characteristic dimensions of the emitting regions at 10 µm are found to be from 1 AU to 10 AU. The 10 µm sizes of our sample stars correlate with the slope of the 10-25 µm infrared spectrum in the sense that the reddest objects are the largest ones. Such a correlation would be consistent with a different geometry in terms of flaring or flat (self-shadowed) disks for sources with strong or moderate mid-infrared excess, respectively. We compare the observed spectrally resolved visibilities with predictions based on existing models of passive centrally irradiated hydrostatic disks made to fit the SEDs of the observed stars. We find broad qualitative agreement of the spectral shape of visibilities corresponding to these models with our observations. Quantitatively, there are discrepancies that show the need for a next step in modelling of circumstellar disks, satisfying both the spatial constraints such as are now available from the MIDI observations and the flux constraints from the SEDs in a consistent way.Key words. stars: circumstellar matter -techniques: interferometric -stars: formation -stars: pre-main-sequenceinfrared: stars Based on observations made with the Very Large Telescope Interferometer at Paranal Observatory.

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Section: Hd 142527mentioning

confidence: 92%

Mid-infrared sizes of circumstellar disks around Herbig Ae/Be stars measured with MIDI on the VLTI

Leinert¹,

Boekel²,

Waters

et al. 2004

A&A

Self Cite

177

179

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“…For both Herbig Ae/Be stars and T Tauri stars, a correlation between shape and strength is observed (e.g., van Boekel et al 2003;Kessler-Silacci et al 2006); strong features typically have low F 11.3 /F 9.8 ratios, which is interpreted as emission from small, amorphous silicate grains, as are found in the ISM. Conversely, a large F 11.3 /F 9.8 ratio (and weak silicate feature strength) suggests the presence of larger and/or more crystalline grains, i.e., more processed dust.…”

Section: First Steps Of Disk Evolutionmentioning

confidence: 96%

Disk Evolution in the Three Nearby Star-Forming Regions of Taurus, Chamaeleon, and Ophiuchus

Furlan

Watson

McClure

et al. 2009

ApJ

149

251

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We analyze samples of Spitzer Infrared Spectrograph spectra of T Tauri stars in the Ophiuchus, Taurus, and Chamaeleon I star-forming regions, whose median ages lie in the <1-2 Myr range. The median mid-infrared spectra of objects in these three regions are similar in shape, suggesting, on average, similar disk structures. When normalized to the same stellar luminosity, the medians follow each other closely, implying comparable mid-infrared excess emission from the circumstellar disks. We use the spectral index between 13 and 31 μm and the equivalent width of the 10 μm silicate emission feature to identify objects whose disk configuration departs from that of a continuous, optically thick accretion disk. Transitional disks, whose steep 13-31 μm spectral slope and near-IR flux deficit reveal inner disk clearing, occur with about the same frequency of a few percent in all three regions. Objects with unusually large 10 μm equivalent widths are more common (20%-30%); they could reveal the presence of disk gaps filled with optically thin dust. Based on their medians and fraction of evolved disks, T Tauri stars in Taurus and Chamaeleon I are very alike. Disk evolution sets in early, since already the youngest region, the Ophiuchus core (L1688), has more settled disks with larger grains. Our results indicate that protoplanetary disks show clear signs of dust evolution at an age of a few Myr, even as early as ∼1 Myr, but age is not the only factor determining the degree of evolution during the first few million years of a disk's lifetime.

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“…The major steps leading to planet formation start by grain growth and dust settling. While the early phases of such grain coagulation has been recently observed in the disk atmosphere (e.g., Przygodda et al 2003;van Boekel et al 2003;Meeus et al 2003) and in the disk midplane (e.g., Calvet et al 2002;Testi et al 2003;Natta et al 2004) of young low-and intermediate-mass stars, no such observation could be performed for the much fainter brown dwarf disks.…”

Section: That Of the T Tauri Disks? Can Brown Dwarf Disks Potentiallymentioning

confidence: 99%

Grain growth and dust settling in a brown dwarf disk

Apai¹,

Pascucci²,

Sterzik

et al. 2004

A&A

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Abstract. We present accurate mid-infrared observations of the disk around the young, bona fide brown dwarf CFHT-BD-Tau 4. We report GEMINI/T-ReCS measurements in the 7.9, 10.4 and 12.3 µm filters, from which we infer the presence of a prominent, broad silicate emission feature. The shape of the silicate feature is dominated by emission from 2 µm amorphous olivine grains. Such grains, being an order of magnitude larger than those in the interstellar medium, are a first proof of dust processing and grain growth in disks around brown dwarfs. The object's spectral energy distribution is below the prediction of the classical flared disk model but higher than that of the two-layer flat disk. A good match can be achieved by using an intermediate disk model with strongly reduced but non-zero flaring. Grain growth and dust settling processes provide a natural explanation for this disk geometry and we argue that such intermediate flaring might explain the observations of several other brown dwarf disks as well.

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Grain growth in the inner regions of Herbig Ae/Be star disks

Cited by 157 publications

References 9 publications

Mid-infrared sizes of circumstellar disks around Herbig Ae/Be stars measured with MIDI on the VLTI

Mid-infrared sizes of circumstellar disks around Herbig Ae/Be stars measured with MIDI on the VLTI

Disk Evolution in the Three Nearby Star-Forming Regions of Taurus, Chamaeleon, and Ophiuchus

Grain growth and dust settling in a brown dwarf disk

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