Molecular content of the circumstellar disk in AB Aurigae

Fuente, A.; Cernicharo, J.; Agúndez, M.; Berné, O.; Goicoechea, J. R.; Alonso-Albi, T.; Marcelino, N.

doi:10.1051/0004-6361/201014905

Cited by 68 publications

(103 citation statements)

References 16 publications

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“…The clear detection of C 17 O confirms the large CO content of this source. H 2 CO is convincingly detected, confirming the result of Fuente et al (2010) using the para-H 2 CO 3 0,3 −2 0,2 line at 218.2 GHz. However, we find no evidence at all for CN or SO from the disk, which were claimed to be detected by these authors.…”

Section: Discussionsupporting

confidence: 82%

“…We only have a narrow (0.4 km s −1 ), 3.5σ feature in CN(2−1) at a velocity consistent with cloud emission. The CN (1−0) line quoted by Fuente et al (2010) must have been residual emission from the cloud. For SO, they report a line intensity of 26 mK km s −1 for the 3 4 −2 3 line, and 60 mK km s −1 for the 5 6 −4 5 transitions, while we obtain a 3σ upper limit of 21 mK km s −1 for the 5 4 −4 3 using the AB Aur velocity and line widths.…”

Section: Discussionmentioning

confidence: 99%

“…For SO, they report a line intensity of 26 mK km s −1 for the 3 4 −2 3 line, and 60 mK km s −1 for the 5 6 −4 5 transitions, while we obtain a 3σ upper limit of 21 mK km s −1 for the 5 4 −4 3 using the AB Aur velocity and line widths. Note that Fuente et al (2010) used a larger throw (120 ) than us in the wobbler switching, so that their results are more susceptible to residual emission from the envelope.…”

Section: Discussionmentioning

confidence: 99%

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A sensitive survey for¹³CO, CN, H₂CO, and SO in the disks of T Tauri and Herbig Ae stars

Guilloteau¹,

Folco²,

Dutrey³

et al. 2013

A&A

108

151

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Aims. We investigate the suitability of several molecular tracers, in particular CN N = 2−1 line emission, as a confusion-free probe of the kinematics of circumstellar disks. Methods. We use the IRAM 30-m telescope to perform a sensitive search for CN N = 2−1 in 42 T Tauri or Herbig Ae systems located principally in the Taurus-Auriga region. 13 CO J = 2−1 is observed simultaneously to provide an indication of the level of confusion with the surrounding molecular cloud. The bandpass also contains two transitions of ortho-H 2 CO, one of SO and the C 17 O J = 2−1 line which provide complementary information on the nature of the emission. Results. While 13 CO is in general dominated by residual emission from the cloud, CN exhibits a high disk detection rate >50% in our sample. We even report CN detection in stars for which interferometric searches failed to detect 12 CO, presumably because of obscuration by a foreground, optically thick, cloud. Comparison between CN and o-H 2 CO or SO line profiles and intensities divide the sample in two main categories. Sources with SO emission are bright and have strong H 2 CO emission, leading in general to [H 2 CO/CN] > 0.5. Furthermore, their line profiles, combined with a priori information on the objects, suggest that the emission is coming from outflows or envelopes rather than from a circumstellar disk. On the other hand, most sources have [H 2 CO/CN] < 0.3, no SO emission, and some of them exhibit clear double-peaked profiles characteristics of rotating disks. In this second category, CN is likely tracing the proto-planetary disks. From the line flux and opacity derived from the hyperfine ratios, we constrain the outer radii of the disks, which range from 300 to 600 AU. The overall gas disk detection rate (including all molecular tracers) is ∼68%, and decreases for fainter continuum sources. Conclusions. The current study demonstrates that gas disks, like dust disks, are ubiquitous around young PMS stars in regions of isolated star formation, and that a large fraction of them have R out > ∼ 300 AU. It also shows the potential of the CN N = 2−1 transition to probe the kinematics of these disks, thereby measuring the stellar mass, using high resolution observations with ALMA.

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Section: Discussionsupporting

confidence: 82%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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A sensitive survey for¹³CO, CN, H₂CO, and SO in the disks of T Tauri and Herbig Ae stars

Guilloteau¹,

Folco²,

Dutrey³

et al. 2013

A&A

108

151

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“…A wide variety of complex organic species have been found in low-and high-mass protostars at the stage when the source is still embedded in a dense envelope (see Herbst & van Dishoeck 2009, for review). For disks, the pure rotational lines of CO, H 2 O, HCO + , H 2 CO, HCN, N 2 H + , CN, C 2 H, SO, DCO + and DCN have been reported but more complex molecules have not yet been detected (e.g., Dutrey et al 1997;Kastner et al 1997;Thi et al 2004;Fuente et al 2010;Henning et al 2010;Öberg et al 2011;Hogerheijde et al 2011). Although these millimeter data have the advantage that they do not suffer from dust extinction and can thus probe down to the midplane, current facilities are only sensitive to the cooler gas in the outer disk (>50 AU).…”

Section: Introductionmentioning

confidence: 99%

Exploring organic chemistry in planet-forming zones

Bast

Lahuis

Dishoeck

et al. 2013

A&A

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Context. Over the last few years, the chemistry of molecules other than CO in the planet-forming zones of disks is starting to be explored with Spitzer and high-resolution ground-based data. However, these studies have focused only on a few simple molecules. Aims. The aim of this study is to put observational constraints on the presence of more complex organic and sulfur-bearing molecules predicted to be abundant in chemical models of disks and to simulate high resolution spectra in view of future missions. Methods. High signal-to-noise ratio (S/N) Spitzer spectra of the near edge-on disks IRS 46 and GV Tau are used to search for midinfrared absorption bands of various molecules. These disks are good laboratories because absorption studies do not suffer from low line/continuum ratios that plague emission data. Simple local thermodynamic equilibrium (LTE) slab models are used to infer column densities (or upper limits) and excitation temperatures. Results. Mid-infrared bands of HCN, C 2 H 2 and CO 2 are clearly detected toward both sources. The HCN and C 2 H 2 absorption arises in warm gas with excitation temperatures of 400−700 K, whereas the CO 2 absorption originates in cooler gas of ∼250 K. Column densities and their ratios are comparable for the two sources. No other absorption features are detected at the 3σ level. Column density limits of the majority of molecules predicted to be abundant in the inner disk -C 2 H 4 , C 2 H 6 , C 6 H 6 , C 3 H 4 , C 4 H 2 , CH 3 , HNC, HC 3 N, CH 3 CN, NH 3 and SO 2 -are determined and compared with disk models. Conclusions. The inferred abundance ratios and limits with respect to C 2 H 2 and HCN are roughly consistent with models of the chemistry in high temperature gas. Models of UV irradiated disk surfaces generally agree better with the data than pure X-ray models. The limit on NH 3 /HCN implies that evaporation of NH 3 -containing ices is only a minor contributor. The inferred abundances and their limits also compare well with those found in comets, suggesting that part of the cometary material may derive from warm inner disk gas. The high resolution simulations show that future instruments on the James Webb Space Telescope (JWST), the Extremely Large Telescopes (ELTs), the Stratospheric Observatory for Infrared Astronomy (SOFIA) and the Space Infrared Telescope for Cosmology and Astrophysics (SPICA) can probe up to an order of magnitude lower abundance ratios and put important new constraints on the models, especially if pushed to high S/Ns.

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“…Higher densities, up to n H = 6 × 10 6 cm −3 , were found by Choi et al (2000); Rizzo et al (2003); and Pilleri et al (2013) to account for the emission of molecular species in the far-IR and radio domains. The UCH ii and the PDRs are surrounded by a moderate density (n H 2 ∼ 5 × 10 4 cm −3 ), cometary-shaped molecular cloud (Fuente et al 2010;Pilleri et al 2012Pilleri et al , 2013.…”

Section: Introductionmentioning

confidence: 99%

Kinematics of the ionized-to-neutral interfaces in Monoceros R2

Pilleri

Fuente

Gérin

et al. 2014

A&A

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Context. Monoceros R2 (Mon R2), at a distance of 830 pc, is the only ultra-compact H ii region (UC H ii) where its associated photon-dominated region (PDR) can be resolved with the Herschel Space Observatory. Aims. Our aim is to investigate observationally the kinematical patterns in the interface regions (i.e., the transition from atomic to molecular gas) associated with Mon R2. Methods. We used the HIFI instrument on board Herschel to observe the line profiles of the reactive ions CH + , OH + , and H 2 O + toward different positions in Mon R2. We derive the column density of these molecules and compare them with gas-phase chemistry models. Results. The reactive ion CH + is detected both in emission (at central and red-shifted velocities) and in absorption (at blue-shifted velocities). The OH + ion is detected in absorption at both blue-and red-shifted velocities, with similar column densities; H 2 O + is not detected at any of the positions, down to a rms of 40 mK toward the molecular peak. At this position, we find that the OH + absorption originates in a mainly atomic medium, and therefore is associated with the most exposed layers of the PDR. These results are consistent with the predictions from photo-chemical models. The line profiles are consistent with the atomic gas being entrained in the ionized gas flow along the walls of the cavity of the H ii region. Based on this evidence, we are able to propose a new geometrical model for this region. Conclusions. The kinematical patterns of the OH + and CH + absorption indicate the existence of a layer of mainly atomic gas for which we have derived, for the first time, some physical parameters and its dynamics.

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Molecular content of the circumstellar disk in AB Aurigae

Cited by 68 publications

References 16 publications

A sensitive survey for¹³CO, CN, H₂CO, and SO in the disks of T Tauri and Herbig Ae stars

A sensitive survey for¹³CO, CN, H₂CO, and SO in the disks of T Tauri and Herbig Ae stars

Exploring organic chemistry in planet-forming zones

Kinematics of the ionized-to-neutral interfaces in Monoceros R2

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Molecular content of the circumstellar disk in AB Aurigae

Cited by 68 publications

References 16 publications

A sensitive survey for13CO, CN, H2CO, and SO in the disks of T Tauri and Herbig Ae stars

A sensitive survey for13CO, CN, H2CO, and SO in the disks of T Tauri and Herbig Ae stars

Exploring organic chemistry in planet-forming zones

Kinematics of the ionized-to-neutral interfaces in Monoceros R2

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Product

Resources

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A sensitive survey for¹³CO, CN, H₂CO, and SO in the disks of T Tauri and Herbig Ae stars

A sensitive survey for¹³CO, CN, H₂CO, and SO in the disks of T Tauri and Herbig Ae stars