First results of the<i>Herschel</i>key program “Dust, Ice and Gas In Time” (DIGIT): Dust and gas spectroscopy of HD 100546

Sturm, B.; Bouwman, J.; Henning, Th.; Evans, Neal J.; Acke, B.; Mulders, Gijs D.; Waters, L.B.F.M.; Dishoeck, E. F. van; Meeus, G.; Green, J. D.; Augereau, J.-C.; Olofsson, J.; Salyk, Colette; Najita, J.; Herczeg, Gregory J.; Kempen, T. A. van; Kristensen, L. E.; Dominik, C.; Carr, John S.; Waelkens, Christoffel; Bergin, Edwin A.; Blake, Geoffrey A.; Brown, J. M.; Chen, J.-H.; Cieza, Lucas A.; Dunham, Michael M.; Glassgold, A. E.; Güdel, M.; Harvey, P. M.; Hogerheijde, M. R.; Jaffe, D. T.; Jørgensen, J. K.; Kim, H. J.; Knez, C.; Lacy, J. H.; Lee, Jeong Eun; Maret, S.; Meijerink, R.; Merın, Bruno; Mundy, Lee G.; Pontoppidan, K. M.; Visser, R.; Yıldız, U. A.

doi:10.1051/0004-6361/201014674

Cited by 75 publications

(102 citation statements)

References 21 publications

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“…More sensitive data could reveal higher J emission lines also for these sources. The result for HD 100546 is similar to that found in an earlier analysis (Sturm et al 2010). We note that the fit predicts line fluxes that are too high when compared to the observations for a few transitions (around 22 → 21, or E up = 1397 K).…”

Section: Rotation Diagramssupporting

confidence: 86%

“…The far-IR lines of CO in HAEBEs and TTS were also observed by DIGIT (Sturm et al 2010) and GASPS (Meeus et al 2012) with the instrument PACS (Poglitsch et al 2010) onboard Herschel (Pilbratt et al 2010). Bruderer et al (2012;hereafter BR12) have modelled pure rotational CO transitions in HD 100546 (Sturm et al 2010).…”

Section: Introductionmentioning

confidence: 90%

“…Bruderer et al (2012;hereafter BR12) have modelled pure rotational CO transitions in HD 100546 (Sturm et al 2010). They have showed the following: 1) On the disc surface, the gas temperature is decoupled from the dust temperature.…”

Section: Introductionmentioning

confidence: 99%

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DIGIT survey of far-infrared lines from protoplanetary discs

Meeus

Salyk

Bruderer

et al. 2013

A&A

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CO is an important component of a protoplanetary disc as it is one of the most abundant gas phase species. Furthermore, observations of CO transitions can be used as a diagnostic of the gas, tracing conditions in both the inner and outer disc. We present Herschel/PACS spectroscopy of a sample of 22 Herbig Ae/Be (HAEBEs) and eight T Tauri stars (TTS), covering the pure rotational CO transitions from J = 14 → 13 up to J = 49 → 48. CO is detected in only five HAEBEs, namely AB Aur, HD 36112, HD 97048, HD 100546, and IRS 48, and in four TTS, namely AS 205, S CrA, RU Lup, and DG Tau. The highest transition detected is J = 36 → 35 with E up of 3669 K, seen in HD 100546 and DG Tau. We construct rotational diagrams for the discs with at least three CO detections to derive T rot and find average temperatures of 270 K for the HAEBEs and 485 K for the TTS. The HD 100546 star requires an extra temperature component at T rot ∼ 900-1000 K, suggesting a range of temperatures in its disc atmosphere, which is consistent with thermo-chemical disc models. In HAEBEs, the objects with CO detections all have flared discs in which the gas and dust are thermally decoupled. We use a small model grid to analyse our observations and find that an increased amount of flaring means higher line flux, as it increases the mass in warm gas. CO is not detected in our flat discs as the emission is below the detection limit. We find that HAEBE sources with CO detections have high L UV and strong PAH emission, which is again connected to the heating of the gas. In TTS, the objects with CO detections are all sources with evidence of a disc wind or outflow. For both groups of objects, sources with CO detections generally have high UV luminosity (either stellar in HAEBEs or due to accretion in TTS), but this is not a sufficient condition for the detection of the far-IR CO lines.

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Section: Rotation Diagramssupporting

confidence: 86%

Section: Introductionmentioning

confidence: 90%

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DIGIT survey of far-infrared lines from protoplanetary discs

Meeus

Salyk

Bruderer

et al. 2013

A&A

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“…We present here 50−200 μm spectra of a sample of protoplanetary disks around Herbig AeBe and T Tauri stars obtained in the context of the "Dust, Ice and Gas in Time" (DIGIT) key program (Sturm et al 2010). The unprecedented sensitivity of the PACS instrument (Poglitsch et al 2010) on board the Herschel Space Observatory (Pilbratt et al 2010) allows for the first time the detection of weak atomic and molecular emission down to a few 10 −18 W m −2 .…”

Section: Introductionmentioning

confidence: 99%

DIGIT survey of far-infrared lines from protoplanetary disks

Fedele

Bruderer

Dishoeck

et al. 2013

A&A

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We present far-infrared (50−200 μm) spectroscopic observations of young pre-main-sequence stars taken with Herschel/PACS as part of the DIGIT key project. The sample includes 16 Herbig AeBe and 4 T Tauri sources observed in SED mode covering the entire spectral range. An additional 6 Herbig AeBe and 4 T Tauri systems have been observed in SED mode with a limited spectral coverage. Multiple atomic fine structure and molecular lines are detected at the source position:The most common feature is the [O i] 63 μm line detected in almost all of the sources, followed by OH. In contrast with CO, OH is detected toward both Herbig AeBe groups (flared and non-flared sources). An isothermal LTE slab model fit to the OH lines indicates column densities of 10 13 < N OH < 10 16 cm −2 , emitting radii 15 < r < 100 AU and excitation temperatures 100 < T ex < 400 K. We used the non-LTE code RADEX to verify the LTE assumption. High gas densities (n ≥ 10 10 cm −3 ) are needed to reproduce the observations. The OH emission thus comes from a warm layer in the disk at intermediate stellar distances. Warm H 2 O emission is detected through multiple lines toward the T Tauri systems AS 205, DG Tau, S CrA and RNO 90 and three Herbig AeBe systems HD 104237, HD 142527, HD 163296 (through line stacking). Overall, Herbig AeBe sources have higher OH/H 2 O abundance ratios across the disk than do T Tauri disks, from near-to far-infrared wavelengths. Far-infrared CH + emission is detected toward HD 100546 and HD 97048. The slab model suggests moderate excitation (T ex ∼ 100 K) and compact (r ∼ 60 AU) emission in the case of HD 100546.Off-source [O i] emission is detected toward DG Tau, whose origin is likely the outflow associated with this source. The [C ii] emission is spatially extended in all sources where the line is detected. This suggests that not all [C ii] emission is associated with the disk and that there is a substantial contribution from diffuse material around the young stars. The flux ratios of the atomic fine structure linesare analyzed with PDR models and require high gas density (n 10 5 cm −3 ) and high UV fluxes (G o ∼ 10 3 −10 7 ), consistent with a disk origin for the oxygen lines for most of the sources.

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“…However, that detection had a low signal-to-noise ratio (S/N) and the shape of the emission band was never analysed in terms of temperature or iron content. Herschel PACS spectra of that particular source were discussed by Sturm et al (2010), who presented the 69 μm band at unprecedented S/N and resolution and who found the emission to emerge from very iron-poor dust at a temperature of about ∼150-200 K.…”

Section: Introductionmentioning

confidence: 99%

The 69μm forsterite band in spectra of protoplanetary disks. Results from theHerschelDIGIT programme

Sturm

Bouwman

Henning

et al. 2013

A&A

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Context. We have analysed far-infrared spectra of 32 circumstellar disks around Herbig Ae/Be and T Tauri stars obtained within the Herschel key programme Dust, Ice and Gas in Time (DIGIT). The spectra were taken with the Photodetector Array Camera and Spectrometer (PACS) on board the Herschel Space Observatory. In this paper we focus on the detection and analysis of the 69 μm emission band of the crystalline silicate forsterite. Aims. This work aims at providing an overview of the 69 μm forsterite bands present in the DIGIT sample. We use characteristics of the emission band (peak position and FWHM) to derive the dust temperature and to constrain the iron content of the crystalline silicates. With this information, constraints can be placed on the spatial distribution of the forsterite in the disk and the formation history of the crystalline grains. Methods. The 69 μm forsterite emission feature is analysed in terms of position and shape to derive the temperature and composition of the dust by comparison to laboratory spectra of that band. The PACS spectra are combined with existing Spitzer IRS spectra and we compare the presence and strength of the 69 μm band to the forsterite bands at shorter wavelengths. Results. A total of 32 disk sources have been observed. Out of these 32, 8 sources show a 69 μm emission feature that can be attributed to forsterite. With the exception of the T Tauri star AS 205, all of the detections are for disks associated with Herbig Ae/Be stars. Most of the forsterite grains that give rise to the 69 μm bands are found to be warm (∼100-200 K) and iron-poor (less than ∼2% iron). AB Aur is the only source where the emission cannot be fitted with iron-free forsterite requiring approximately 3-4% of iron. Conclusions. Our findings support the hypothesis that the forsterite grains form through an equilibrium condensation process at high temperatures. The large width of the emission band in some sources may indicate the presence of forsterite reservoirs at different temperatures. The connection between the strength of the 69 and 33 μm bands shows that at least part of the emission in these two bands originates fom the same dust grains. We further find that any model that can explain the PACS and the Spitzer IRS observations must take the effects of a wavelength dependent optical depth into account. We find weak indications of a correlation of the detection rate of the 69 μm band with the spectral type of the host stars in our sample. However, the sample size is too small to obtain a definitive result.

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First results of theHerschelkey program “Dust, Ice and Gas In Time” (DIGIT): Dust and gas spectroscopy of HD 100546

Cited by 75 publications

References 21 publications

DIGIT survey of far-infrared lines from protoplanetary discs

DIGIT survey of far-infrared lines from protoplanetary discs

DIGIT survey of far-infrared lines from protoplanetary disks

The 69μm forsterite band in spectra of protoplanetary disks. Results from theHerschelDIGIT programme

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