Search for HOOH in Orion

Liseau, R.; Larsson, Bengt

doi:10.1051/0004-6361/201526830

Cited by 28 publications

(35 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The derived dust opacity curve has been computed for a particular volume density of the gas, n d (H) and this ought to be consistent with that 13 For ρ Oph A, the (anisotropic) radiation field is more intense by two orders of magnitude (Liseau et al 1999). …”

Section: Discussionsupporting

confidence: 60%

“…west and east of the dense core, with respective radii of 0.06 pc and 0.5 pc. The bright B2 star HD 147889 is situated more than half a parsec away to the southwest and behind the cloud (Liseau et al 1999). Together, these stellar radiation sources are heating the dust of ρ Oph A from the outside.…”

Section: Extended Dust Emissionmentioning

confidence: 99%

“…1). In addition, Liseau et al (1999) in excess of 100 K. These phenomena probably refer to the outer layers of the cloud. The N 2 H + (6-5) line could be used to probe that temperature regime in a coherent map.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Gas and dust in the star-forming regionρ Oph A

Liseau

Larsson

Lunttila

et al. 2015

A&A

Self Cite

View full text Add to dashboard Cite

Aims. We aim at determining the spatial distribution of the gas and dust in star-forming regions and address their relative abundances in quantitative terms. We also examine the dust opacity exponent β for spatial and/or temporal variations. Methods. Using mapping observations of the very dense ρ Oph A core, we examined standard 1D and non-standard 3D methods to analyse data of far-infrared and submillimetre (submm) continuum radiation. The resulting dust surface density distribution can be compared to that of the gas. The latter was derived from the analysis of accompanying molecular line emission, observed with Herschel from space and with APEX from the ground. As a gas tracer we used N 2 H + , which is believed to be much less sensitive to freeze-out than CO and its isotopologues. Radiative transfer modelling of the N 2 H + (J = 3−2) and (J = 6−5) lines with their hyperfine structure explicitly taken into account provides solutions for the spatial distribution of the column density N(H 2 ), hence the surface density distribution of the gas. Results. The gas-to-dust mass ratio is varying across the map, with very low values in the central regions around the core SM 1. The global average, =88, is not far from the canonical value of 100, however. In ρ Oph A, the exponent β of the power-law description for the dust opacity exhibits a clear dependence on time, with high values of 2 for the envelope-dominated emission in starless Class -1 sources to low values close to 0 for the disk-dominated emission in Class III objects. β assumes intermediate values for evolutionary classes in between. Conclusions. Since β is primarily controlled by grain size, grain growth mostly occurs in circumstellar disks. The spatial segregation of gas and dust, seen in projection toward the core centre, probably implies that, like C 18 O, also N 2 H + is frozen onto the grains.

show abstract

Section: Discussionsupporting

confidence: 60%

Section: Extended Dust Emissionmentioning

confidence: 99%

See 1 more Smart Citation

Gas and dust in the star-forming regionρ Oph A

Liseau

Larsson

Lunttila

et al. 2015

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…In two recent papers (Feng et al 2015;Liseau & Larsson 2015) a tentative detection of three species has been reported. We do not confirm these detections, as discussed below.…”

Section: Non-confirmation Of Species In Orionmentioning

confidence: 99%

The complexity of Orion: an ALMA view

Pagani

Favre

Goldsmith

et al. 2017

A&A

View full text Add to dashboard Cite

Context. We wish to improve our understanding of the Orion central star formation region (Orion-KL) and disentangle its complexity. Aims. We collected data with ALMA during cycle 2 in 16 GHz of total bandwidth spread between 215.1 and 252.0 GHz with a typical sensitivity of 5 mJy/beam (2.3 mJy/beam from 233.4 to 234.4 GHz) and a typical beam size of 1 . 7 × 1 . 0 (average position angle of 89 • ). We produced a continuum map and studied the emission lines in nine remarkable infrared spots in the region including the hot core and the compact ridge, plus the recently discovered ethylene glycol peak. Methods. We present the data, and report the detection of several species not previously seen in Orion, including n-and i-propyl cyanide (C 3 H 7 CN), and the tentative detection of a number of other species including glycolaldehyde (CH 2 (OH)CHO). The first detections of gGg ethylene glycol (gGg (CH 2 OH) 2 ) and of acetic acid (CH 3 COOH) in Orion are presented in a companion paper. We also report the possible detection of several vibrationally excited states of cyanoacetylene (HC 3 N), and of its 13 C isotopologues. We were not able to detect the 16 O 18 O line predicted by our detection of O 2 with Herschel, due to blending with a nearby line of vibrationally excited ethyl cyanide. We do not confirm the tentative detection of hexatriynyl (C 6 H) and cyanohexatriyne (HC 7 N) reported previously, or of hydrogen peroxide (H 2 O 2 ) emission. Results. We report a complex velocity structure only partially revealed before. Components as extreme as −7 and +19 km s −1 are detected inside the hot region. Thanks to different opacities of various velocity components, in some cases we can position these components along the line of sight. We propose that the systematically redshifted and blueshifted wings of several species observed in the northern part of the region are linked to the explosion that occurred ∼500 yr ago. The compact ridge, noticeably farther south displays extremely narrow lines (∼1 km s −1 ) revealing a quiescent region that has not been affected by this explosion. This probably indicates that the compact ridge is either over 10 000 au in front of or behind the rest of the region. Conclusions. Many lines remain unidentified, and only a detailed modeling of all known species, including vibrational states of isotopologues combined with the detailed spatial analysis offered by ALMA enriched with zero-spacing data, will allow new species to be detected.

show abstract

“…The widespread distribution of Denriched formaldehyde and the detection of H 2 O 2 in ρ Oph A (Bergman et al 2011a,b) both support the idea that the O 2 could be present following the evaporation of ice mantles from dust grains. A search for H 2 O 2 in Orion was unsuccessful (Liseau & Larsson 2015) although the upper limits for hydrogen peroxide in interstellar ices, H 2 O 2 /H 2 O< 9%, do not rule out it being quite abundant on dust grains (Smith et al 2011). In Orion, the O 2 emission is confined to the H 2 Peak 1 position and the originally reported abundance ratio was O 2 /H 2 ∼ 10 −6 (Goldsmith et al 2011b).…”

Section: Discussionmentioning

confidence: 99%

A SEARCH FOR O₂ IN CO-DEPLETED MOLECULAR CLOUD CORES WITH HERSCHEL

Wirström

Charnley

Cordiner

et al. 2016

ApJ

View full text Add to dashboard Cite

The general lack of molecular oxygen in molecular clouds is an outstanding problem in astrochemistry. Extensive searches with SWAS, Odin and Herschel have only produced two detections; upper limits to the O 2 abundance in the remaining sources observed are about 1000 times lower than predicted by chemical models. Previous atomic oxygen observations and inferences from observations of other molecules indicated that high abundances of O atoms might be present in dense cores exhibiting large amounts of CO depletion. Theoretical arguments concerning the oxygen gas-grain interaction in cold dense cores suggested that, if O atoms could survive in the gas after most of the rest of the heavy molecular material has frozen out on to dust, then O 2 could be formed efficiently in the gas. Using Herschel HIFI we searched a small sample of four depletion cores -L1544, L694-2, L429, Oph D -for emission in the low excitation O 2 N J =3 3 -1 2 line at 487.249 GHz. Molecular oxygen was not detected and we derive upper limits to its abundance in the range N(O 2 )/N(H 2 )≈ (0.6 − 1.6) × 10 −7 . We discuss the absence of O 2 in the light of recent laboratory and observational studies.

show abstract

Search for HOOH in Orion

Cited by 28 publications

References 19 publications

Gas and dust in the star-forming regionρ Oph A

Gas and dust in the star-forming regionρ Oph A

The complexity of Orion: an ALMA view

A SEARCH FOR O₂ IN CO-DEPLETED MOLECULAR CLOUD CORES WITH HERSCHEL

Contact Info

Product

Resources

About

Search for HOOH in Orion

Cited by 28 publications

References 19 publications

Gas and dust in the star-forming regionρ Oph A

Gas and dust in the star-forming regionρ Oph A

The complexity of Orion: an ALMA view

A SEARCH FOR O2 IN CO-DEPLETED MOLECULAR CLOUD CORES WITH HERSCHEL

Contact Info

Product

Resources

About

A SEARCH FOR O₂ IN CO-DEPLETED MOLECULAR CLOUD CORES WITH HERSCHEL