A high HDO/H${}_2$O ratio in the Class I protostar L1551 IRS5

Abstract

Water is a very abundant molecule in star-forming regions. Its deuterium fractionation is an important tool for understanding its formation and evolution during the star and planet formation processes. While the HDO/H${}_2$O ratio has been determined toward several Class 0 protostars and comets, the number of studies toward Class I protostars is limited. We aim to study the water deuteration toward the Class I binary protostar L1551 IRS5 and to investigate the effect of evolutionary stage and environment on variations in the water D/H ratio. Observations were made using the NOEMA interferometer. The HDO 3${}_{1,2}$-2${}_{2,1}$ transition at 225.9 GHz and the H${}_2^{18}$O 3${}_{1,3}$-2${}_{2,0}$ transition at 203.4 GHz were covered with a spatial resolution of 0.5'' $\times$ 0.8'', while the HDO 4${}_{2,2}$-4${}_{2,3}$ transition at 143.7 GHz was observed with a resolution of 2.0'' $\times$ 2.5''. We used both LTE and non-LTE models. The three transitions are detected. The line profiles display two peaks, one at $\sim$6 km s${}^{-1}$ and one at $\sim$9 km s${}^{-1}$. We derive an HDO/H${}_2$O ratio of (2.1 $\pm$ 0.8) $\times$ 10${}^{-3}$ for the redshifted component and a lower limit of $>$ 0.3 $\times$ 10${}^{-3}$ for the blueshifted component due to the blending with the redshifted CH${}_3$OCH${}_3$ emission. The HDO/H${}_2$O in L1551 IRS5 is similar to the ratios in isolated Class 0 sources and to the Class I V883 Ori, while it is significantly higher than in the clustered Class 0 sources and the comets. This suggests that the chemistry of protostars in low source densities clouds share more similarities with the isolated sources than the protostars of very dense clusters. If Class 0 protostars with few sources around and isolated Class 0 objects are comparable in the HDO/H${}_2$O ratio, it would mean that there is little water reprocessing from the Class 0 to Class I protostellar stage.

arXiv commentAccepted in A&A, 10 pages, 8 figures

References in corpus (35)

• Astropy: A Community Python Package for Astronomy
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• A computer program for fast non-LTE analysis of interstellar line spectra
• How to Calculate Molecular Column Density
• Detection of the Water Reservoir in a Forming Planetary System
• The ancient heritage of water ice in the solar system
• ISOCAM observations of the rho Ophiuchi cloud: Luminosity and mass functions of the pre-main sequence embedded cluster
• A Large Catalog of Accurate Distances to Local Molecular Clouds: The Gaia DR2 Edition
• Imaging the water-snow line during a protostellar outburst
• The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds. III. Perseus Observed with IRAC
• The ALMA-PILS survey: Isotopic composition of oxygen-containing complex organic molecules toward IRAS 16293-2422B
• Water in star-forming regions (WISH): Physics and chemistry from clouds to disks as probed by Herschel spectroscopy
• A Near-IR Spectroscopic Survey of FU Orionis Objects
• A study of deuterated water in the low-mass protostar IRAS16293-2422
• Herschel measurements of the D/H and 16O/18O ratios in water in the Oort-cloud comet C/2009 P1 (Garradd)
• Isotopic ratios of H, C, N, O, and S in comets C/2012 F6 (Lemmon) and C/2014 Q2 (Lovejoy)
• Terrestrial deuterium-to-hydrogen ratio in water in hyperactive comets
• A Herschel Study of D/H in Water in the Jupiter-Family Comet 45P/Honda-Mrkos-Pajdusakova and Prospects for D/H Measurements with CCAT
• Reconstructing the history of water ice formation from HDO/H2O and D2O/HDO ratios in protostellar cores
• The deuterium fractionation of water on solar-system scales in deeply-embedded low-mass protostars
• The 16OH/18OH and OD/OH isotope ratios in comet C/2002 T7 (LINEAR)
• Accretion of water in carbonaceous chondrites: current evidence and implications for the delivery of water to early Earth
• Warm water deuterium fractionation in IRAS 16293-2422 - The high-resolution ALMA and SMA view
• A 3D view of the Taurus star-forming region by Gaia and Herschel: multiple populations related to the filamentary molecular cloud
• FAUST I. The hot corino at the heart of the prototypical Class I protostar L1551 IRS5
• The HDO/H2O ratio in gas in the inner regions of a low-mass protostar
• High D${}_2$O/HDO ratio in the inner regions of the low-mass protostar NGC1333 IRAS2A
• ALMA observations of water deuteration: A physical diagnostic of the formation of protostars
• Water deuterium fractionation in the inner regions of two solar type protostars
• Missing water in Class I protostellar disks
• Resolved ALMA continuum image of the circumbinary ring and circumstellar disks in the L1551 IRS 5 system
• Modeling chemistry during star formation: Water deuteration in dynamic star-forming regions
• Circumbinary Disks of the Protostellar Binary Systems in the L1551 Region
• Hot and dense water in the inner 25 AU of SVS13-A

Cited by in corpus (8)

• JWST detections of amorphous and crystalline HDO ice toward massive protostars
• HDO ice detected toward an isolated low-mass protostar with JWST
• Was Earth's water acquired locally during the earliest phases of the Solar System formation?
• Chemical inventory of the envelope of the Class I protostar L1551 IRS 5
• The hot corino-like chemistry of four FUor-like protostars
• Molecular inventory of a young eruptive star's environment -- Case study of the classical FU Orionis star V1057 Cyg
• Water vapor emission at the warm cavity wall of the HD 100546 disk as revealed by ALMA
• Hunting for methanol in the water rich, planet forming disk around HL Tau