Arcsecond resolution images of the chemical structure of the low-mass protostar IRAS 16293-2422

Jørgensen, J. K.; Bourke, Tyler L.; Luong, Q. Nguyên; Takakuwa, Shigehisa

doi:10.1051/0004-6361/201117139

Cited by 104 publications

(195 citation statements)

References 33 publications

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“…Interferometric data of the HDO 3 1,2 −2 2,1 transition show that, in addition to the main emission coming from the source A, a weaker component of HDO is emitted at about 6 from core A (see Fig. 20 in Jørgensen et al 2011). The beam size of the IRAM-30 m telescope at 81 GHz encompasses this component and could explain the lack of predicted flux as well as the different line profile.…”

Section: Determination Of the Hdo Abundancementioning

confidence: 98%

“…As source A is more massive than source B, we considered that the structure is centered on core A. According to interferometric data of the HDO 3 1,2 −2 2,1 line at 226 GHz, deuterated water is mainly emitted by core A (Jørgensen et al 2011 Crimier et al (2010). The expected abundance profile of water is added (dashed-dotted line) on an arbitrary Y-scale.…”

Section: H 18mentioning

confidence: 99%

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A study of deuterated water in the low-mass protostar IRAS 16293-2422

Coutens¹,

Vastel²,

Caux³

et al. 2012

A&A

133

236

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Context. Water is a primordial species in the emergence of life, and comets may have brought a large fraction to Earth to form the oceans. To understand the evolution of water from the first stages of star formation to the formation of planets and comets, the HDO/H 2 O ratio is a powerful diagnostic. Aims. Our aim is to determine precisely the abundance distribution of HDO towards the low-mass protostar IRAS 16293-2422 and learn more about the water formation mechanisms by determining the HDO/H 2 O abundance ratio. Results. It is the first time that so many HDO and H 182 O transitions have been detected towards the same source with high spectral resolution. We derive an inner HDO abundance (T ≥ 100 K) of about 1.7 × 10 −7 and an outer HDO abundance (T < 100 K) of about 8 × 10 −11 . To reproduce the HDO absorption lines observed at 894 and 465 GHz, it is necessary to add an absorbing layer in front of the envelope. It may correspond to a water-rich layer created by the photodesorption of the ices at the edges of the molecular cloud. At a 3σ uncertainty, the HDO/H 2 O ratio is 1.4-5.8% in the hot corino, whereas it is 0.2-2.2% in the outer envelope. It is estimated at ∼4.8% in the added absorbing layer. Conclusions. Although it is clearly higher than the cosmic D/H abundance, the HDO/H 2 O ratio remains lower than the D/H ratio derived for other deuterated molecules observed in the same source. The similarity of the ratios derived in the hot corino and in the added absorbing layer suggests that water formed before the gravitational collapse of the protostar, contrary to formaldehyde and methanol, which formed later once the CO molecules had depleted on the grains.

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Section: Determination Of the Hdo Abundancementioning

confidence: 98%

Section: H 18mentioning

confidence: 99%

A study of deuterated water in the low-mass protostar IRAS 16293-2422

Coutens¹,

Vastel²,

Caux³

et al. 2012

A&A

133

236

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“…The determination of the centroid velocity toward each source is a matter of debate, where different studies present different results. While Bisschop et al (2008) argued that the high-excitation lines of the complex organics peak at V LSR = 1.5−2.5 km s −1 toward both sources, Jørgensen et al (2011) reported average systemic velocities of 3.2 and 2.7 km s −1 and average line widths of 2.6 and 1.9 km s −1 for A and B, respectively.…”

Section: Introductionmentioning

confidence: 98%

“…Several studies (e.g., Kuan et al 2004;Bottinelli et al 2004;Rao et al 2009;Bisschop et al 2008;Crimier et al 2010;Jørgensen et al 2011) have focused on I16293 to characterize the A&A 544, L7 (2012) respective nature of the two continuum sources. Indeed, I16293 is known to have a quadrupolar outflow (Walker et al 1988;Mizuno et al 1990;Castets et al 2001;Rao et al 2009) suggesting the existence of a binary system.…”

Section: Introductionmentioning

confidence: 99%

The first ALMA view of IRAS 16293-2422

Pineda

Maury

Fuller

et al. 2012

A&A

120

164

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Aims. We focus on the kinematical properties of a proto-binary to study the infall and rotation of gas toward its two protostellar components. Methods. We present ALMA Science Verification observations with high-spectral resolution of IRAS 16293-2422 at 220.2 GHz. The wealth of molecular lines in this source and the very high spectral resolution offered by ALMA allow us to study the gas kinematics with unprecedented detail. Results. We present the first detection of an inverse P-Cygni profile toward source B in the three brightest lines. The line profiles are fitted with a simple two-layer model to derive an infall rate of 4.5 × 10 −5 M yr −1 . This infall detection would rule-out the previously suggested possibility that source B is a T Tauri star. A position velocity diagram for source A shows evidence of rotation with an axis close to the line-of-sight.

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“…The broadband capabilities of modern interferometers allow many spectral lines to be observed in a single correlator setup, enabling astronomers to simultaneously trace multiple astrophysical phenomena, or undertake unbiased line surveys to work toward complete molecular inventories (e.g., Jørgensen et al 2011;Coutens et al 2016;Müller et al 2016). Within these data sets, many scientifically interesting lines may be weak or not detected due to low column densities or intrinsically low line strengths.…”

Section: Introductionmentioning

confidence: 99%

Detecting Weak Spectral Lines in Interferometric Data through Matched Filtering

Loomis

Öberg

Andrews

et al. 2018

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Modern radio interferometers enable observations of spectral lines with unprecedented spatial resolution and sensitivity. In spite of these technical advances, many lines of interest are still at best weakly detected and therefore necessitate detection and analysis techniques specialized for the low signal-to-noise ratio (S/N) regime. Matched filters can leverage knowledge of the source structure and kinematics to increase sensitivity of spectral line observations. Application of the filter in the native Fourier domain improves S/N while simultaneously avoiding the computational cost and ambiguities associated with imaging, making matched filtering a fast and robust method for weak spectral line detection. We demonstrate how an approximate matched filter can be constructed from a previously observed line or from a model of the source, and we show how this filter can be used to robustly infer a detection significance for weak spectral lines. When applied to ALMA Cycle 2 observations of CH 3 OH in the protoplanetary disk around TW Hya, the technique yields a ≈53% S/N boost over aperture-based spectral extraction methods, and we show that an even higher boost will be achieved for observations at higher spatial resolution. A Python-based open-source implementation of this technique is available under the MIT license at https://github.com/AstroChem/VISIBLE.

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Arcsecond resolution images of the chemical structure of the low-mass protostar IRAS 16293-2422

Cited by 104 publications

References 33 publications

A study of deuterated water in the low-mass protostar IRAS 16293-2422

A study of deuterated water in the low-mass protostar IRAS 16293-2422

The first ALMA view of IRAS 16293-2422

Detecting Weak Spectral Lines in Interferometric Data through Matched Filtering

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