CO emission from discs around isolated HAeBe and Vega-excess stars

Dent, W. R. F.; Greaves, J. S.; Coulson, I. M.

doi:10.1111/j.1365-2966.2005.08938.x

Cited by 212 publications

(333 citation statements)

References 65 publications

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“…A uniform disk fit to the CO(3-2) emission, using the MIRIAD task imfit, derives an outer radius of 290 au for the CO gas, similar to the location of the inner dust ring (Biller et al 2015). This is similar to the outer radius derived from the CO line profile in single-dish observations (Dent et al 2005). Our integrated flux measurements are similar to those of previous CO(3-2) observations of the HD 141569 disk (Zuckerman et al 1995;Dent et al 2005).…”

Section: Observations and Resultssupporting

confidence: 77%

“…This is similar to the outer radius derived from the CO line profile in single-dish observations (Dent et al 2005). Our integrated flux measurements are similar to those of previous CO(3-2) observations of the HD 141569 disk (Zuckerman et al 1995;Dent et al 2005). The improved spatial resolution of uniform weighting of the CO(3-2) data (1 2×0 6 versus 1 5×1 0 for natural weighting) reveals a double-peaked structure indicative of an inner hole in the CO gas (Figure 1).…”

Section: Observations and Resultssupporting

confidence: 66%

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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: Observations and Resultssupporting

confidence: 77%

Section: Observations and Resultssupporting

confidence: 66%

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 is optically thin to UV continuum radiation and the grains have grown to at least µm size [45]. Nevertheless, gas is still present since the CO J=2-1 and 3-2 millimeter [11] and the v = 1 − 0 infrared [4] lines have been detected. Moreover, PAHs have been seen, albeit at a low level [68].…”

Section: A Disk Model Examplementioning

confidence: 99%

Photoprocesses in protoplanetary disks

2006

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Circumstellar disks are exposed to intense ultraviolet (UV) radiation from the young star. In the inner disks, the UV radiation can be enhanced by more than seven orders of magnitude compared with the average interstellar radiation field, resulting in a physical and chemical structure that resembles that of a dense photon-dominated region (PDR). This intense UV field affects the chemistry, the vertical structure of the disk, and the gas temperature, especially in the surface layers. The parameters which make disks different from more traditional PDRs are discussed, including the shape of the UV radiation field, grain growth, the absence of PAHs, the gas/dust ratio and the presence of inner holes. Illustrative infrared spectra from the Spitzer Space Telescope are shown. New photodissociation cross sections for selected species, including simple ions, are presented. Also, a summary of cross sections at the Lyman α 1216Å line, known to be strong for some T Tauri stars, is made. Photodissociation and ionization rates are computed for different radiation fields with color temperatures ranging from 30000 to 4000 K and grain sizes up to a few µm. The importance of a proper treatment of the photoprocesses is illustrated for the transitional disk toward HD 141569A which includes grain growth.

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“…These low-J transitions originate in cold, optically thick CO that is located in the outer disc and are routinely detected in HAEBEs (e.g., Thi et al 2001;Dent et al 2005) and in TTS (e.g., Koerner & Sargent 1995;Öberg et al 2010). As the lines are optically thick, the outer disc radius can be estimated from the line profile (e.g., Dent et al 2005;Panić et al 2008).…”

Section: Introductionmentioning

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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CO emission from discs around isolated HAeBe and Vega-excess stars

Cited by 212 publications

References 65 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

Photoprocesses in protoplanetary disks

DIGIT survey of far-infrared lines from protoplanetary discs

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