Chemistry and Physics of a Low-metallicity Hot Core in the Large Magellanic Cloud

Shimonishi, Takashi; Das, Ankan; Sakai, Nami; Tanaka, Kei E. I.; Aikawa, Yuri; Onaka, Takashi; Watanabe, Yoshimasa; Nishimura, Y.

doi:10.3847/1538-4357/ab6e6b

Cited by 26 publications

(54 citation statements)

References 92 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our grid of models also suggest that the COM abundances depend more sensitively on T min when A amb v is lower. It is in line with the recent observations, which show large abundance variations of COMs among cores in LMC and SMC (Shimonishi et al 2016;Sewi lo et al 2018;Shimonishi et al 2018Shimonishi et al , 2020, since the visual extinction is lower in those low-metalicity galaxies compared with that in our Galaxy. Vidal et al (2019) calculated the three-phase model in 110 models of star-forming core of Vaytet & Haugbølle (2017).…”

Section: Comparison With Previous Worksupporting

confidence: 93%

Chemical Variation among Protostellar Cores: Dependence on Prestellar Core Conditions

Aikawa,

Furuya,

Yamamoto

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

Hot corino chemistry and warm carbon chain chemistry (WCCC) are driven by gasgrain interactions in star-forming cores: radical-radical recombination reactions to form complex organic molecules (COMs) in the ice mantle, sublimation of CH 4 and COMs, and their subsequent gas-phase reactions. These chemical features are expected to depend on the composition of ice mantle which is set in the prestellar phase. We calculated the gas-grain chemical reaction network considering a layered ice-mantle structure in star-forming cores, to investigate how the hot corino chemistry and WCCC depend on the physical condition of the static phase before the onset of gravitational collapse. We found that WCCC becomes more active, if the temperature is lower, or the visual extinction is lower in the static phase, or the static phase is longer. Dependence of hot corino chemistry on the static-phase condition is more complex. While CH 3 OH is less abundant in the models with warmer static phase, some COMs are formed efficiently in those warm models, since there are various formation paths of COMs. If the visual extinction is lower, photolysis makes COMs less abundant in the static phase. Once the collapse starts and visual extinction increases, however, COMs can be formed efficiently. Duration of the static phase does not largely affect COM abundances. Chemical diversity between prototypical hot corinos and hybrid sources, in which both COMs and carbon chains are reasonably abundant, can be explained by the variation of prestellar conditions. Deficiency of gaseous COMs in prototypical WCCC sources is, however, hard to reproduce within our models.

show abstract

Section: Comparison With Previous Worksupporting

confidence: 93%

Chemical Variation among Protostellar Cores: Dependence on Prestellar Core Conditions

Aikawa,

Furuya,

Yamamoto

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…We use the reaction pathways shown in the Appendix (see Table A1) to check the fate of the P-bearing species in various parts of the ISM (diffuse clouds, PDRs, hot corino, and hot cores). Here, we employ mainly two models to study the chemical evolution of these species; a) spectral synthesis code, Cloudy (version 17.02, last described by Ferland et al 2017) and b) Chemical Model for Molecular Cloud (hereafter CMMC) code (Das et al 2015;Gorai et al 2017a,b;Sil et al 2018;Shimonishi et al 2020).…”

Section: Chemical Modelmentioning

confidence: 99%

Chemical complexity of phosphorous bearing species in various regions of the Interstellar medium

Sil,

Srivastav,

Bhat

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

Phosphorus related species are not known to be as omnipresent in space as hydrogen, carbon, nitrogen, oxygen, and sulfur-bearing species. Astronomers spotted very few P-bearing molecules in the interstellar medium and circumstellar envelopes. Limited discovery of the P-bearing species imposes severe constraints in modeling the P-chemistry. In this paper, we carry out extensive chemical models to follow the fate of P-bearing species in diffuse clouds, photon-dominated or photodissociation regions (PDRs), and hot cores/corinos. We notice a curious correlation between the abundances of PO and PN and atomic nitrogen. Since N atoms are comparatively abundant in diffuse clouds and PDRs than in the hot core/corino region, PO/PN reflects < 1 in diffuse clouds, << 1 in PDRs, and > 1 in the late warm-up evolutionary phase of the hot core/corino regions. During the end of the post-warm-up phase, we obtain PO/PN > 1 for hot core and < 1 for its low mass analog. We employ a radiative transfer model to investigate the transitions of some of the P-bearing species in diffuse cloud and hot core regions and estimate the line profiles. Our study estimates the required integration time to observe these transitions with ground-based and space-based telescopes. We also carry out quantum chemical computation of the infrared features of PH 3 along with various impurities. We notice that SO 2 overlaps with the PH 3 bendingscissoring modes around ∼ (1000 − 1100) cm −1 . We also find that the presence of CO 2 can strongly influence the intensity of the stretching modes around ∼ 2400 cm −1 of PH 3 .

show abstract

“…Methanol (CH 3 OH), methyl cyanide (CH 3 CN), and larger COMs have been found in the LMC toward hot cores (Sewiło et al 2018;Shimonishi et al 2020): small (D 0.1 pc), hot (T kin 100 K), and dense (n H 10 6−7 cm −3 ) regions around forming massive stars where ice mantles have recently been removed from dust grains as a result of thermal evaporation and/or sputtering in shock waves (e.g., Garay & Lizano 1999;Kurtz et al 2000;Cesaroni 2005;Palau et al 2011). A typical Galactic hot core has a very rich spectrum at submm wavelengths including lines from many complex organics -the products of interstellar grain-surface chemistry or postdesorption gas chemistry (e.g., Herbst & van Dishoeck 2009;Oberg 2016;Jørgensen et al 2020).…”

Section: Hot Molecular Cores In the Lmcmentioning

confidence: 99%

“…As described in Section 5, we adopted T (CH 3 CN) for hot cores N 105-2 A and 2 B to calculate N (H 2 ). For ST16, we recalculated the molecular abundances from Shimonishi et al (2020) by estimating N (H 2 ) using the dust temperature of 60 K provided in the paper (consistent with T (CH 3 CN) of 53 +10 −7 K) and assuming the same LMC dust-to-gas ratio as for N 105 and N 113 (Section 5). T (CH 3 OH) is the only temperature determination available for hot cores A1 and B3 in N 113 and it was used for the analysis.…”

Section: Chemical Differences Between Hot Cores N 105-2mentioning

confidence: 99%

ALMA Observations of Molecular Complexity in the Large Magellanic Cloud: The N105 Star-Forming Region

Sewiło,

Cordiner,

Charnley

et al. 2022

Preprint

View full text Add to dashboard Cite

The Large Magellanic Cloud (LMC) is the nearest laboratory for detailed studies on the formation and survival of complex organic molecules (COMs), including biologically important ones, in lowmetallicity environments-typical for earlier cosmological epochs. We report the results of 1.2 mm continuum and molecular line observations of three fields in the star-forming region N 105 with the Atacama Large Millimeter/submillimeter Array (ALMA). N 105 lies at the western edge of the LMC bar with on-going star formation traced by H 2 O, OH, and CH 3 OH masers, ultracompact H ii regions, and young stellar objects. Based on the spectral line modeling, we estimated rotational temperatures, column densities, and fractional molecular abundances for twelve 1.2 mm continuum sources. We identified sources with a range of chemical make-ups, including two bona fide hot cores and four hot core candidates. The CH 3 OH emission is widespread and associated with all the continuum sources. COMs CH 3 CN and CH 3 OCH 3 are detected toward two hot cores in N 105 together with smaller molecules typically found in Galactic hot cores (e.g., SO 2 , SO, and HNCO) with the molecular abundances roughly scaling with metallicity. We report a tentative detection of the astrobiologically relevant formamide molecule (NH 2 CHO) toward one of the hot cores; if confirmed, this would be the first detection of NH 2 CHO in an extragalactic sub-solar metallicity environment. We suggest that metallicity inhomogeneities resulting from the tidal interactions between the LMC and the Small

show abstract

Chemistry and Physics of a Low-metallicity Hot Core in the Large Magellanic Cloud

Cited by 26 publications

References 92 publications

Chemical Variation among Protostellar Cores: Dependence on Prestellar Core Conditions

Chemical Variation among Protostellar Cores: Dependence on Prestellar Core Conditions

Chemical complexity of phosphorous bearing species in various regions of the Interstellar medium

ALMA Observations of Molecular Complexity in the Large Magellanic Cloud: The N105 Star-Forming Region

Contact Info

Product

Resources

About