A search for mid-infrared molecular hydrogen emission from protoplanetary disks

Carmona, A.; Ancker, M. E. van den; Henning, Th.; Pavlyuchenkov, Ya. N.; Dullemond, C. P.; Goto, Miwa; Thi, Wing-Fai; Bouwman, J.; Waters, L. B. F. M.

doi:10.1051/0004-6361:20077846

Cited by 55 publications

(82 citation statements)

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“…Employing Chiang & Goldreich (1997) Herbig Ae two-layer disk models (using the implementation by Dullemond et al 2001, described in Carmona et al 2008b, we calculated the amount of gas in the surface layer at T surf > 1000 K for disks of mass 10, 40 and 100 M J (see Figs. 4 and 5 of Carmona et al 2008b). We found that the mass of gas at T surf > 1000 K is ∼0.01 M moon .…”

Section: H 2 Near-ir Emission In the Context Of Diverse Disk Structurmentioning

confidence: 76%

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A survey for near-infrared H₂emission in Herbig Ae/Be stars: emission from the outer disks of HD 97048 and HD 100546

Plas

Ancker

Audard

et al. 2011

A&A

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We report on a sensitive search for H 2 1-0 S(1), 1-0 S(0) and 2-1 S(1) ro-vibrational emission at 2.12, 2.22 and 2.25 μm in a sample of 15 Herbig Ae/Be stars employing CRIRES, the ESO-VLT near-infrared high-resolution spectrograph, at R ∼ 90 000. We report the detection of the H 2 1-0 S(1) line toward HD 100546 and HD 97048. In the other 13 targets, the line is not detected. The H 2 1-0 S(0) and 2-1 S(1) lines are undetected in all sources. These observations are the first detection of near-IR H 2 emission in HD 100546. The H 2 1-0 S(1) lines observed in HD 100546 and HD 97048 are observed at a velocity consistent with the rest velocity of both stars, suggesting that they are produced in the circumstellar disk. In HD 97048 the emission is spatially resolved and it is observed to extend at least up to 200 AU from the star. We report an increase of one order of magnitude in the H 2 1-0 S(1) line flux with respect to previous measurements taken in 2003 for this star, which suggests line variability. In HD 100546 the emission is tentatively spatially resolved and may extend at least up to 50 AU from the star. Modeling of the H 2 1-0 S(1) line profiles and their spatial extent with flat Keplerian disks shows that most of the emission is produced at a radius larger than 5 AU. Upper limits to the H 2 1-0 S(0)/1-0 S(1) and H 2 2-1 S(1)/1-0 S(1) line ratios in HD 97048 are consistent with H 2 gas at T > 2000 K and suggest that the emission observed may be produced by X-ray excitation. The upper limits for the line ratios for HD 100546 are inconclusive. Because the H 2 emission is located at large radii, for both sources a thermal emission scenario (i.e., gas heated by collisions with dust) is implausible. We argue that the observation of H 2 emission at large radii may be indicative of an extended disk atmosphere at radii >5 AU. This may be explained by a hydrostatic disk in which gas and dust are thermally decoupled or by a disk wind caused by photoevaporation.

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Section: H 2 Near-ir Emission In the Context Of Diverse Disk Structurmentioning

confidence: 76%

“…In the mid-IR, H 2 pure-rotational transitions trace thermal emission of warm gas at few hundred K (e.g. Thi et al 2001;Bitner et al 2007;Martin-Zaïdi et al 2007, 2010Lahuis et al 2007;Carmona et al 2008b). In the specific case of the near-infrared, A&A 533, A39 (2011) Meeus et al (2001).…”

Section: Introductionmentioning

confidence: 99%

A survey for near-infrared H₂emission in Herbig Ae/Be stars: emission from the outer disks of HD 97048 and HD 100546

Plas

Ancker

Audard

et al. 2011

A&A

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“…Observations show that the emission has the characteristic shape suggestive of a rotating disk (Carr 1989). The CO rovibrational band at 4.7 μm is estimated to arise within 1-10 AU from the star (e.g., Najita et al 2003;Blake & Boogert 2004;Rettig et al 2004;Salyk et al 2007;Carmona et al 2008b) with characteristic temperatures between 100 to a few 1000 K.…”

Section: Introductionmentioning

confidence: 99%

Searching for gas emission lines inSpitzerInfrared Spectrograph (IRS) spectra of young stars in Taurus

Baldovin-Saavedra

Audard

Güdel

et al. 2011

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Context. Our knowledge of circumstellar disks has traditionally been based on studies of dust. However, gas dominates the disk mass and its study is key to our understanding of accretion, outflows, and ultimately planet formation. The Spitzer Space Telescope provides access to gas emission lines in the mid-infrared, providing crucial new diagnostics of the physical conditions in accretion disks and outflows. Aims. We seek to identify gas emission lines in mid-infrared spectra of 64 pre-main-sequence stars in Taurus. Using line luminosities and other known star-disk-outflow parameters, we aim to identify correlations that will help to constrain gas heating, excitation mechanisms, and the line formation. Methods. We have based our study on Spitzer observations using the Infrared Spectrograph (IRS), mainly with the high-resolution modules. Line luminosities (or 3σ upper limits) have been obtained by fitting Gaussian profiles to the lines. We have further searched for correlations between the line luminosities and different parameters related to the star-disk system. Results. We have detected H 2 (17.03, 28.22 μm) emission in 6 objects, [Ne II] (12.81 μm) emission in 18 objects, and [Fe II] (17.93, 25.99 μm) emission in 7 objects. [Ne II] detections are found primarily in Class II objects. The luminosity of the [Ne II] line (L NeII ) is in general higher for objects known to drive jets than for those without known jets, but the two groups are not statistically distinguishable. L NeII is correlated with X-ray luminosity, but for Class II objects only. L NeII is also correlated with disk mass and accretion rate when the sample is divided into high and low accretors. Furthermore, we find correlations of L NeII with mid-IR continuum luminosity and with luminosity of the [O I] (6300 Å) line, the latter being an outflow tracer. L [FeII] correlates withṀ acc . No correlations were found between L H 2 and several tested parameters. Conclusions. Our study reveals a general trend toward accretion-related phenomena as the origin of the gas emission lines. Shocks in jets and outflowing material are more likely to play a significant role than shocks in infalling material. The role of X-ray irradiation is less prominent but still present for [Ne II], in particular for Class II sources, while the lack of correlation between [Fe II] and [Ne II] points toward different emitting mechanisms.

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“…Both the geometry and the dust in Herbig Ae/Be (HAEBE) discs are A&A 559, A84 (2013) only two objects. Earlier, Bitner et al (2008), Carmona et al (2008), and Martin-Zaïdi et al (2009 searched for pure rotational lines of H 2 at 17.035 µm in a sample of 20 HAEBEs; only two detections were reported. In TTS, the success rate is a little higher: Lahuis et al (2007) have detected mid-IR H 2 emission lines in six TTS, while Bary et al (2008) have found five more H 2 detections in the near-IR.…”

Section: Introductionmentioning

confidence: 99%

DIGIT survey of far-infrared lines from protoplanetary discs

Meeus

Salyk

Bruderer

et al. 2013

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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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A search for mid-infrared molecular hydrogen emission from protoplanetary disks

Cited by 55 publications

References 40 publications

A survey for near-infrared H₂emission in Herbig Ae/Be stars: emission from the outer disks of HD 97048 and HD 100546

A survey for near-infrared H₂emission in Herbig Ae/Be stars: emission from the outer disks of HD 97048 and HD 100546

Searching for gas emission lines inSpitzerInfrared Spectrograph (IRS) spectra of young stars in Taurus

DIGIT survey of far-infrared lines from protoplanetary discs

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A search for mid-infrared molecular hydrogen emission from protoplanetary disks

Cited by 55 publications

References 40 publications

A survey for near-infrared H2emission in Herbig Ae/Be stars: emission from the outer disks of HD 97048 and HD 100546

A survey for near-infrared H2emission in Herbig Ae/Be stars: emission from the outer disks of HD 97048 and HD 100546

Searching for gas emission lines inSpitzerInfrared Spectrograph (IRS) spectra of young stars in Taurus

DIGIT survey of far-infrared lines from protoplanetary discs

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A survey for near-infrared H₂emission in Herbig Ae/Be stars: emission from the outer disks of HD 97048 and HD 100546

A survey for near-infrared H₂emission in Herbig Ae/Be stars: emission from the outer disks of HD 97048 and HD 100546