Observations of Herbig Ae/Be stars with<i>Herschel</i>/PACS

Meeus, G.; Montesinos, B.; Mendigutía, I.; Kamp, I.; Thi, Wing-Fai; Eiroa, C.; Grady, C. A.; Mathews, Geoffrey S.; Sandell, G.; Martin-Zaidi, C.; Brittain, S.; Dent, W. R. F.; Howard, Christian D.; Ménard, F.; Pinte, C.; Roberge, Aki; Vandenbussche, B.; Williams, Jonathan P.

doi:10.1051/0004-6361/201219225

Cited by 156 publications

(205 citation statements)

References 118 publications

(105 reference statements)

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“…Kamp & van Zadelhoff (2001) predict [O I] and [C II] play a large role in gas cooling, while Thi et al (2014), in their modeling of the HD 141569 system, find that CO itself can play a major role. Strong far-infrared emission from [O I] and [C II], at levels more comparable to protoplanetary disks than to debris disks, has been measured from the disk around HD 141569 (Meeus et al 2012) although these lines may only contribute significantly to the upper low density regions of the disk rather than the midplane being traced by our CO observations. Two-dimensional photodissociation region models (e.g., Hollenbach & Tielens 1999) predict that at the densities where CO becomes the dominant coolant, but before collisional equilibrium with the dust sets in, the gas temperature can drop below that of the dust.…”

Section: Discussionmentioning

confidence: 64%

Resolved Co Gas Interior to the Dust Rings of the Hd 141569 Disk

Flaherty

Hughes

Andrews

et al. 2016

ApJ

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The disk around HD 141569 is one of a handful of systems whose weak infrared emission is consistent with a debris disk, but still has a significant reservoir of gas. Here we report spatially resolved millimeter observations of the CO(3-2) and CO(1-0) emission as seen with the Submillimeter Array and CARMA. We find that the excitation temperature for CO is lower than expected from cospatial blackbody grains, similar to previous observations of analogous systems, and derive a gas mass that lies between that of gas-rich primordial disks and gas-poor debris disks. The data also indicate a large inner hole in the CO gas distribution and an outer radius that lies interior to the outer scattered light rings. This spatial distribution, with the dust rings just outside the gaseous disk, is consistent with the expected interactions between gas and dust in an optically thin disk. This indicates that gas can have a significant effect on the location of the dust within debris disks.

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Section: Discussionmentioning

confidence: 64%

Resolved Co Gas Interior to the Dust Rings of the Hd 141569 Disk

Flaherty

Hughes

Andrews

et al. 2016

ApJ

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“…These differences are likely due to different excitation mechanisms (e.g. collisions, infrared pumping, shocks) and different physical conditions (temperature and column density (Fedele et al 2012;Meeus et al 2012) and have been confirmed through a stacking analysis. Two other Herbig AeBe stars show hints of H 2 O emission: HD 142527 and HD 104237.…”

Section: H 2 Omentioning

confidence: 67%

“…The difference between the mid-and far-IR ratios are not significant. Herbig AeBe: the major difference between short and long wavelengths is the lack of any H 2 O lines at near-IR (Mandell et al 2008;Fedele et al 2011) whereas weak H 2 O lines are detected at mid-and far-IR in some sources (Pontoppidan et al 2010;Fedele et al 2012;Meeus et al 2012). Even though the detection rate of warm H 2 O is low and the individual lines are weak (< a few 10 −17 W m −2 ), this finding suggests a different H 2 O abundance between the inner and outer disk.…”

Section: Comparison To Near-and Mid-ir Spectroscopymentioning

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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“…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%

“…The HAEBE stars with strong L UV and flaring discs (group I) often have a high [O ] 63 µm line flux (Meeus et al 2012; Table 2. Observed CO line fluxes in W m −2 × 10 −18 (first row) and adjacent continuum flux density in Jy (second row).…”

Section: Relation With the (Uv) Luminositymentioning

confidence: 99%

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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Observations of Herbig Ae/Be stars withHerschel/PACS

Cited by 156 publications

References 118 publications

Resolved Co Gas Interior to the Dust Rings of the Hd 141569 Disk

Resolved Co Gas Interior to the Dust Rings of the Hd 141569 Disk

DIGIT survey of far-infrared lines from protoplanetary disks

DIGIT survey of far-infrared lines from protoplanetary discs

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