Similar levels of deuteration in the pre-stellar core L1544 and the protostellar core HH211

Giers, K.; Spezzano, S.; Caselli, P.; Wirström, E. S.; Sipilä, O.; Pineda, Jaime E.; Redaelli, E.; Bop, Cheikh T; Lique, François

doi:10.1051/0004-6361/202346433

Cited by 4 publications

(2 citation statements)

References 110 publications

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“…Aikawa et al (2008) show that the CO sublimation radius, where T  20 K, is only ∼100 au at the time of protostar formation, similar to the resolution of our ALMA observations. Deuterium fractionations can remain high in the envelopes of young protostellar sources (Giers et al 2023), in agreement with the observed N 2 D + and NH 2 D within N6 (but offset from N6-mm).…”

Section: N6: Comparison With First Hydrostatic Core Predictionssupporting

confidence: 86%

The Initial Conditions of Clustered Core Collapse: Multiwavelength Analysis of Oph A SM1N and N6 at 100 au Resolution

Friesen,

Bourke,

Caselli

et al. 2024

ApJ

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We present new Atacama Large Millimeter/submillimeter Array (ALMA) continuum and NH2D, N2D+, and H2D+ line emission at matched, ∼100 au resolution toward the dense star-forming cores SM1N and N6 within the Ophiuchus molecular cloud. We determine the density and temperature structure of SM1N based on radiative transfer modeling and simulated observations of the multiwavelength continuum emission at 0.8, 2, and 3 mm. We show that SM1N is best fit by either a broken power-law or Plummer-like density profile with high central densities (n ∼ 108 cm−3), and an inner transition radius of only ∼80–300 au. The free-fall time of the inner region is only a few ×103 yr. The continuum modeling rules out the presence of an embedded first hydrostatic core (FHSC) or protostar. SM1N is therefore a dynamically unstable but still starless core. We find that NH2D is likely depleted at high densities within SM1N. The nonthermal velocity dispersions increase from NH2D to N2H+ and H2D+, possibly tracing increasing (but still subsonic) infall speeds at higher densities as predicted by some models of starless core contraction. Toward N6, we confirm the previous ALMA detection of a faint, embedded point source (N6-mm) in 0.8 mm continuum emission. NH2D and N2D+ avoid N6-mm within ∼100 au, while H2D+ is not strongly detected toward N6. The distribution of these tracers is consistent with heating by a young, warm object. N6-mm thus remains one of the best candidate FHSCs detected so far, although its observed (sub)millimeter luminosity remains below predictions for FHSCs.

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Section: N6: Comparison With First Hydrostatic Core Predictionssupporting

confidence: 86%

The Initial Conditions of Clustered Core Collapse: Multiwavelength Analysis of Oph A SM1N and N6 at 100 au Resolution

Friesen,

Bourke,

Caselli

et al. 2024

ApJ

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“…During the early stages of high-mass star-forming regions, they are deeply embedded in their parental molecular clouds. Consequently, recent observational studies focus on studying the cold gas (e.g., Wienen et al 2021;Galloway-Sprietsma et al 2022;Sakai et al 2022;van Gelder et al 2022;Giers et al 2023) and dust (e.g., Svoboda et al 2016;Sanhueza et al 2019;Redaelli et al 2022;Li et al 2023;Morii et al 2023) in high-mass star-forming regions at (sub)millimeter wavelengths.…”

Section: Introductionmentioning

confidence: 99%

Molecular Deuterations in Massive Starless Clump Candidates

Yang,

Wang,

Qiu

et al. 2024

ApJS

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Deuterated molecules are valuable probes for investigating the evolution and the kinematics in the earliest stages of star formation. In this study, we conduct a comprehensive investigation by performing a single-point survey of 101 starless clump candidates, and carrying out on-the-fly (OTF) observations of 11 selected sources, focusing on deuterated molecular lines using the IRAM 30 m telescope. In the single-point observation, we make 46 detections for DCO+ J = 1−0, 12 for DCN J = 1−0, 51 for DNC J = 1−0, 7 for N2D+ J = 1−0, 20 for DCO+ J = 2−1, and 10 for DCN J = 2−1. The starless clump candidates with deuterated molecule detections exhibit lower median kinetic temperatures and a narrower H2CO (1(0,1)−0(0,0)) median full width at half maximum compared to those without such detections, while simultaneously displaying similar median values of 1.1 mm intensity, mass, and distance. Furthermore, our OTF observations reveal that deuterated molecules predominantly have peaks near the 1.1 mm continuum peaks, with the DCO+ J = 1−0 emission demonstrating higher intensity in the deuterated peak region compared to the DCN and DNC J = 1−0 emissions. Additionally, the majority of emissions from deuterated molecules and 13C isotopologues exhibit peak positions close to those of the 1.1 mm continuum peaks. By analyzing the 20″ × 20″ regions with strongest deuterated emissions in the OTF observations, we estimated deuterated abundances of 0.004−0.045, 0.011−0.040, and 0.004−0.038 for D frac(HCN), D frac(HCO+), and D frac(HNC), respectively. The differential detection of deuterated molecular lines in our OTF observations could be attributed to variations in critical densities and formation pathways.

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Chemical inventory of the envelope of the Class I protostar L1551 IRS 5

Marchand,

Coutens,

Scigliuto

et al. 2024

A&A

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Episodic accretion in protostars leads to luminosity outbursts that end up heating their surroundings. This rise in temperature pushes the snow lines back, enabling the desorption of chemical species from dust grain surfaces, which may significantly alter the chemical history of the accreting envelope. However, a limited number of extensive chemical surveys of eruptive young stars have been performed thus far. In the present study, we carry out a large spectral survey of the binary Class I protostar L1551 IRS 5, known to be a FUor-like object, in the 3mm and 2mm bands with the IRAM-30m telescope. As a result, we detected more than 400 molecular lines. The source displays a great chemical richness with the detection of 75 species, including isotopologues. Among these species, there are 13 hydrocarbons, 25 N-bearing species, 30 O-bearing species, 15 S-bearing species, 12 deuterated molecules, and a total of 10 complex organic molecules (l-C$_4$H$_2$, CH$_3$CCH, CH$_2$DCCH, CH$_3$CHO, CH$_3$CN, CH$_3$OCH$_3$, CH$_3$OCHO, CH$_3$OH, CH$_2$DOH, and HC$_5$N). With the help of local thermodynamic equilibrium (LTE) and non-LTE models, we determined the column densities of most molecules as well as excitation and kinetic temperatures. While most of those molecules trace the cold envelope ($ 20$ K), the OCS and CH$_3$OH emission arise from the warm ($> 100$ K) innermost ($< 2$ regions. We compared the chemical inventory of L1551 IRS 5 and its column density ratios, including isotopic ratios, with other protostellar sources. A broad chemical diversity is seen among Class I objects. More observations with both single-dish telescopes and interferometers are needed to characterize the diversity in a larger sample of protostars, while more astrochemical models would help explain this diversity, in addition to the impact of luminosity outbursts on the chemistry of protostellar envelopes.

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Similar levels of deuteration in the pre-stellar core L1544 and the protostellar core HH211

Cited by 4 publications

References 110 publications

The Initial Conditions of Clustered Core Collapse: Multiwavelength Analysis of Oph A SM1N and N6 at 100 au Resolution

The Initial Conditions of Clustered Core Collapse: Multiwavelength Analysis of Oph A SM1N and N6 at 100 au Resolution

Molecular Deuterations in Massive Starless Clump Candidates

Chemical inventory of the envelope of the Class I protostar L1551 IRS 5

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