Long Carbon Chains in the Warm Carbon-chain-chemistry Source L1527: First Detection of C<sub>7</sub>H in Molecular Clouds

Araki, Mitsunori; Takano, Shuro; Sakai, Nami; Yamamoto, Satoshi; Oyama, Takahiro; Kuze, Nobuhiko; Tsukiyama, Koichi

doi:10.3847/1538-4357/aa8637

Cited by 20 publications

(9 citation statements)

References 41 publications

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“…B1-b: Marcelino et al (2005, 2009, 2010); Agúndez et al (2008); Öberg et al (2010); Cernicharo et al (2012); Loison et al (2016, 2017); Fuente et al (2016); Widicus Weaver et al (2017); Marcelino et al (in preparation). L1527: Sakai et al (2008b); Marcelino et al (2009, 2010); Araki et al (2017); Yoshida et al (2019). Adopted H 2 column densities (needed to convert molecular column densities to fractional abundances) are 1 × 10 22 cm –2 for TMC-1 (Cernicharo & Guélin 1987), 5.4 × 10 22 cm –2 for L1544 (Jiménez-Serra et al 2016), 7.6 × 10 22 cm –2 for B1-b (Daniel et al 2013), and 2.8 × 10 22 cm –2 for L1527 (Jørgensen et al 2002).…”

Section: Figmentioning

confidence: 99%

A sensitive λ 3 mm line survey of L483

Agúndez

Marcelino

Cernicharo

et al. 2019

A&A

111

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An exhaustive chemical characterization of dense cores is mandatory to our understanding of chemical composition changes from a starless to a protostellar stage. However, only a few sources have had their molecular composition characterized in detail. Here we present a λ 3 mm line survey of L483, a dense core around a Class 0 protostar, which was observed with the IRAM 30m telescope in the 80-116 GHz frequency range. We detected 71 molecules (140 including different isotopologs), most of which are present in the cold and quiescent ambient cloud according to their narrow lines (FWHM ~0.5 km s−1) and low rotational temperatures (≲10 K). Of particular interest among the detected molecules are the cis isomer of HCOOH, the complex organic molecules HCOOCH3, CH3OCH3, and C2H5OH, a wide variety of carbon chains, nitrogen oxides like N2O, and saturated molecules like CH3SH, in addition to eight new interstellar molecules (HCCO, HCS, HSC, NCCNH+, CNCN, NCO, H2NCO+, and NS+) whose detection has already been reported. In general, fractional molecular abundances in L483 are systematically lower than in TMC-1 (especially for carbon chains), tend to be higher than in L1544 and B1-b, and are similar to those in L1527. Apart from the overabundance of carbon chains in TMC-1, we find that L483 does not have a marked chemical differentiation with respect to starless/prestellar cores like TMC-1 and L1544, although it does chemically differentiate from Class 0 hot corino sources like IRAS 16293–2422. This fact suggests that the chemical composition of the ambient cloud of some Class 0 sources could be largely inherited from the dark cloud starless/prestellar phase. We explore the use of potential chemical evolutionary indicators, such as the HNCO/C3S, SO2/C2S, and CH3SH/C2S ratios, to trace the prestellar/protostellar transition. We also derived isotopic ratios for a variety of molecules, many of which show isotopic ratios close to the values for the local interstellar medium (remarkably all those involving 34S and 33S), while there are also several isotopic anomalies like an extreme depletion in 13C for one of the two isotopologs of c-C3H2, a drastic enrichment in 18O for SO and HNCO (SO being also largely enriched in 17O), and different abundances for the two 13C substituted species of C2H and the two 15N substituted species of N2H+. We report the first detection in space of some minor isotopologs like c-C3D. The exhaustive chemical characterization of L483 presented here, together with similar studies of other prestellar and protostellar sources, should allow us to identify the main factors that regulate the chemical composition of cores along the process of formation of low-mass protostars.

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Section: Figmentioning

confidence: 99%

A sensitive λ 3 mm line survey of L483

Agúndez

Marcelino

Cernicharo

et al. 2019

A&A

111

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“…This trend is more significant in longer chains as reported by Sakai et al (2008b). Note that Araki et al (2017) As for COMs, the column density ratios relative to CH 3 OH in L1527 and TMC-1 are compared in Table 11. The column densities in TMC-1 are taken from Soma et al (2018).…”

Section: Tmc-1mentioning

confidence: 99%

An unbiased spectral line survey observation toward the low-mass star-forming region L1527

Yoshida

Sakai

Nishimura

et al. 2019

Publications of the Astronomical Society of Japan

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An unbiased spectral line survey toward a solar-type Class 0/I protostar, IRAS04368+2557, in L1527 has been carried out in the 3 mm band with the Nobeyama 45 m telescope. L1527 is known as a warm carbon-chain chemistry (WCCC) source, which harbors abundant unsaturated organic species such as C n H (n = 3, 4, 5, . . .) in a warm and dense region near the protostar. The observation covers the frequency range from 80 to 116 GHz. A supplementary observation has also been conducted in the 70 GHz band to observe fundamental transitions of deuterated species. In total, 69 molecular species are identified, among which 27 species are carbon-chain species and their isomers, including their minor isotopologues. This spectral line survey provides us with a good template of the chemical composition of the WCCC source.comparison with other sources such as starless cores showing cold carbon-chain chemistry (e.g., TMC-1 (CP); Kaifu et al. 2004) will give us valuable information on formation of these molecules in space.As an independent study, a similar spectral line survey observation toward this source was also carried out with the IRAM 30 m telescope, as part of the ASAI (Astrochemical Surveys At Iram) program. Its summary result has recently been reported (Lefloch et al. 2018), although detailed data exploitation has not been presented. The ASAI survey almost covers the frequency range of our survey in the 3 mm band with a larger beam size by a factor of 1.5.Nevertheless, independent spectral line surveys with different telescopes are always important for the fundamental sources such as L1527, because they give opportunities to confirm the consistency of the results, and also provide additional information such as the source sizes by taking advantage of the different beam sizes. Here, we report the results of our spectral line survey with NRO 45 m. 2 Observation The spectral line survey observations of L1527 were carried out with NRO 45 m during the seasons from 2006 to 2012. The frequency range was from 79.8 GHz to 116.8 GHz. The observed position was (α 2000 , δ 2000 ) = (4 h 39 m 53. s 89, 26 • 03 11. 0), which is the position of the protostar (Sakai et al. 2008b). In this observation, we used the SIS mixer receivers, S80 and S100, simultaneously from 2006 to 2008, while we employed the dual-polarization sidebandseparating SIS receiver T100H/V (Nakajima et al. 2008) from 2009 to 2012. The system temperatures varied from 250 to 350 K in the former and from 150 to 250 K in the latter.The intensity scale was calibrated by using the chopper-wheel method, and the calibration uncertainty is estimated to be better than 20%. The telescope pointing was checked once every 1 to 1.5 hour by observing the nearby SiO maser sources (NML-Tau and Ori-KL). The pointing accuracy was ensured to be better than 6 . The main-beam efficiency (η mb ) at 86 GHz was 0.43 from 2006 to 2008, 0.49 in 2009, and 0.42 from 2010 to 2012, as reported on the NRO website. The antenna temperature (T * A ) is converted to the main-beam brightness temperature (T...

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“…It was first found in the cold and less dense envelope of the giant star-forming region Sagittarius B2(N) (Hollis et al 2006). More recently, c-H 2 C 3 O was detected in four dark clouds or prestellar cores, TMC-1, B1-b, L483, and Lupus-1A (Loison et al 2016), and in the lowmass star-forming region L1527 (Araki et al 2017). Benson et al (1973) presented the first account on the rotational spectrum of cyclopropenone.…”

Section: Introductionmentioning

confidence: 99%

Rotational spectroscopy of isotopic cyclopropenone, c-H₂C₃O, and determination of its equilibrium structure

Müller

Brahmi

Guillemin

et al. 2021

A&A

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Context. Cyclopropenone was first detected in the cold and less dense envelope of the giant molecular cloud Sagittarius B2(N). It was found later in several cold dark clouds and it may be possible to detect its minor isotopic species in these environments. In addition, the main species may well be identified in warmer environments. Aims. We aim to extend existing line lists of isotopologs of c-H 2 C 3 O from the microwave to the millimeter region and create one for the singly deuterated isotopolog to facilitate their detections in space. Furthermore, we aim to extend the line list of the main isotopic species to the submillimeter region and to evaluate an equilibrium structure of the molecule. Methods. We employed a cyclopropenone sample in natural isotopic composition to investigate the rotational spectra of the main and 18 O-containing isotopologs as well as the two isotopomers containing one 13 C atom. Spectral recordings of the singly and doubly deuterated isotopic species were obtained using a cyclopropenone sample highly enriched in deuterium. We recorded rotational transitions in the 70−126 GHz and 160−245 GHz regions for all isotopologs and also in the 342−505 GHz range for the main species. Quantum-chemical calculations were carried out to evaluate initial spectroscopic parameters and the differences between ground-state and equilibrium rotational parameters in order to derive semi-empirical equilibrium structural parameters. Results. We determined new or improved spectroscopic parameters for six isotopologs and structural parameters according to different structure models. Conclusions. The spectroscopic parameters are accurate enough to identify minor isotopic species at centimeter and millimeter wavelengths while those of the main species are deemed to be reliable up to 1 THz. Our structural parameters differ from earlier ones. The deviations are attributed to misassignments in the earlier spectrum of one isotopic species.

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Long Carbon Chains in the Warm Carbon-chain-chemistry Source L1527: First Detection of C₇H in Molecular Clouds

Cited by 20 publications

References 41 publications

A sensitive λ 3 mm line survey of L483

A sensitive λ 3 mm line survey of L483

An unbiased spectral line survey observation toward the low-mass star-forming region L1527

Rotational spectroscopy of isotopic cyclopropenone, c-H₂C₃O, and determination of its equilibrium structure

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Long Carbon Chains in the Warm Carbon-chain-chemistry Source L1527: First Detection of C7H in Molecular Clouds

Cited by 20 publications

References 41 publications

A sensitive λ 3 mm line survey of L483

A sensitive λ 3 mm line survey of L483

An unbiased spectral line survey observation toward the low-mass star-forming region L1527

Rotational spectroscopy of isotopic cyclopropenone, c-H2C3O, and determination of its equilibrium structure

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Long Carbon Chains in the Warm Carbon-chain-chemistry Source L1527: First Detection of C₇H in Molecular Clouds

Rotational spectroscopy of isotopic cyclopropenone, c-H₂C₃O, and determination of its equilibrium structure