Linking the dust and chemical evolution: Taurus and Perseus

Bop, Cheikh T; Lique, François; Esplugues, G.; Rodríguez-Baras, M.; Krämer, C.; Romero, C.; Fuente, A.; Caselli, P.; Rivière-Marichalar, P.; Kirk, J. M.; Chacón-Tanarro, A.; Roueff, E.; Mroczkowski, Tony; Bhandarkar, Tanay; Devlin, Mark J.; Dicker, Simon; Lowe, Ian; Mason, B. S.; Sarazin, Craig L.; Sievers, Jonathan

doi:10.1051/0004-6361/202245000

Cited by 9 publications

(5 citation statements)

References 146 publications

(200 reference statements)

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“…The variations of β 1,2 observed by us are well above the calibration errors and indicate systematic variations of the grain population emitting at mm wavelengths. Similar β values have been found in these and other cores of Taurus using also other millimeter/submillimeter cameras [3,5,12,13,20]. [15].…”

Section: The Dust Emissivity Indexsupporting

confidence: 84%

“…The filamentary structure of NGC1333-C7 exhibits an almost constant β 1,2 ∼ 1.6 with the sole exception of core #2 exhibiting a much lower value of ∼ 1.0. Interestingly, core #2 is a Class I protostellar object and its Deuteration, measured by the ratio of DCN/H 13 CN abundances, is significantly lower than for the other cores of this region [12]. Its low β 1,2 value indicates bare grains, devoid of ice mantles, consistent with a more evolved state.…”

Section: Discussionmentioning

confidence: 91%

“…The dual-band camera NIKA2 [16] at the IRAM 30-meter telescope was used to map four regions in the nearby molecular filaments of Taurus and Perseus simultaneously at 1 and 2 mm wavelengths. The regions were selected from a survey of gas phase abundances in 29 starless cores covering different star formation activity, GEMS 1 , a large program using the EMIR eightband heterodyne receiver at the 30-meter telescope [6,12]. The gas phase abundances of Carbon, Oxygen, Nitrogen, and Sulphur were measured together with the ionization fraction X(e − ) by spatially resolved cuts of molecular key tracers through the cores.…”

Section: Cores In Taurus and Perseusmentioning

confidence: 99%

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NIKA2 observations of starless cores in Taurus and Perseus

Kramer,

Adam,

Ade

et al. 2024

EPJ Web Conf.

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Dusty starless cores play an important role in regulating the initial phases of the formation of stars and planets. In their interiors, dust grains coagulate and ice mantles form, thereby changing the millimeter emissivities and hence the ability to cool. We mapped four regions with more than a dozen cores in the nearby Galactic filaments of Taurus and Perseus using the NIKA2 camera at the IRAM 30-meter telescope. Combining the 1mm to 2mm flux ratio maps with dust temperature maps from Herschel allowed to create maps of the dust emissivity index β1,2 at resolutions of 2430 and 5600 a.u. in Taurus and Perseus, respectively. Here, we study the variation with total column densities and environment. β1,2 values at the core centers (Av =12 – 19 mag) vary significantly between ~ 1.1 and 2.3. Several cores show a strong rise of β1,2 from the outskirts at ~ 4 mag to the peaks of optical extinctions, consistent with the predictions of grain models and the gradual build-up of ice mantles on coagulated grains in the dense interiors of starless cores.

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Section: The Dust Emissivity Indexsupporting

confidence: 84%

Section: Discussionmentioning

confidence: 91%

Section: Cores In Taurus and Perseusmentioning

confidence: 99%

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NIKA2 observations of starless cores in Taurus and Perseus

Kramer,

Adam,

Ade

et al. 2024

EPJ Web Conf.

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“…The 15 NH 3 collisional coefficients are not available. However, we expect that they can differ at most by 10-15%; similar differences have been found in 15 N-bearing isotopologues of HNC and HCN (see Navarro-Almaida et al 2023). Furthermore, for T K < 15 K, T rot ≈ T K with a maximum difference of < 10%.…”

Section: Appendix B: Spectral Fitting Proceduressupporting

confidence: 69%

Nitrogen fractionation in ammonia and its insights into nitrogen chemistry

Redaelli¹,

Bizzocchi²,

Caselli³

et al. 2023

A&A

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Context. Observations of the nitrogen isotopic ratio 14N/15N in the interstellar medium are becoming more frequent thanks to increased telescope capabilities. However, interpreting these data is still puzzling. In particular, measurements of 14N/15N in diazenylium have revealed high levels of anti-fractionation in cold cores, which is challenging to explain. Aims. By using astrophysical simulations coupled with a gas-grain chemical code, it has been suggested that the 15N-depletion in prestellar cores could be inherited from the initial stages, when 14N15N is selectively photodissociated and 15N atoms deplete onto the dust grain, forming ammonia ices. Our aim is to test this hypothesis. Methods. We targeted three sources (the prestellar core L1544, the protostellar envelope IRAS4A, and the shocked region L1157-B1) with distinct degrees of desorption or sputtering of the ammonia ices. We observed the ammonia isotopologues with the Green Bank Telescope, and we inferred the ammonia 14N/15N via spectral fitting of the observed inversion transitions. Results.15NH3 (1,1) is detected in L1544 and IRAS4A, whilst only upper limits are deduced in L1157-B1. The NH3 isotopic ratio is significantly lower towards the protostar (14N/15N = 210 ± 50) than at the centre of L1544 (14N/15N = 390 ± 40), where it is consistent with the elemental value. We also present the first spatially resolved map of NH3 nitrogen isotopic ratio towards L1544. Conclusions. Our results are in agreement with the hypothesis that ammonia ices are enriched in 15N, leading to a decrease in the 14N/15N ratio when the ices are sublimated back into the gas phase for instance due to the temperature rise in protostellar envelopes. The ammonia 14N/15N value at the centre of L1544 is a factor of 2 lower than that of N2H+, which can be explained if a significant fraction of nitrogen remains in atomic form and if the ammonia formed on the dust grains is released in the gas phase via non-thermal desorption.

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“…) andNavarro-Almaida et al (2023). Following the same methodology explained inFuente et al (2019) and Rodríguez-Baras et al (2021), we assumed X(HCN)/X(H 13 CN) = 60 to estimate the HCN abundance.…”

mentioning

confidence: 99%

Gas phase Elemental abundances in Molecular cloudS (GEMS)

Rocha,

Roncero,

Bulut

et al. 2023

A&A

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Context. Carbon monosulphide (CS) is among the few sulphur-bearing species that have been widely observed in all environments, including in the most extreme, such as diffuse clouds. Moreover, CS has been widely used as a tracer of the gas density in the interstellar medium in our Galaxy and external galaxies. Therefore, a complete understanding of its chemistry in all environments is of paramount importance for the study of interstellar matter. Aims. Our group is revising the rates of the main formation and destruction mechanisms of CS. In particular, we focus on those involving open-shell species for which the classical capture model might not be sufficiently accurate. In this paper, we revise the rates of reactions CH + S → CS + H and C2 + S → CS + C. These reactions are important CS formation routes in some environments such as dark and diffuse warm gas. Methods. We performed ab initio calculations to characterize the main features of all the electronic states correlating to the open shell reactants. For CH+S, we calculated the full potential energy surfaces (PESs) for the lowest doublet states and the reaction rate constant with a quasi-classical method. For C2+S, the reaction can only take place through the three lower triplet states, which all present deep insertion wells. A detailed study of the long-range interactions for these triplet states allowed us to apply a statistic adiabatic method to determine the rate constants. Results. Our detailed theoretical study of the CH + S → CS + H reaction shows that its rate is nearly independent of the temperature in a range of 10–500 K, with an almost constant value of 5.5 × 10−11 cm3 s−1 at temperatures above 100 K. This is a factor of about 2–3 lower than the value obtained with the capture model. The rate of the reaction C2 + S → CS + C does depend on the temperature, and takes values close to 2.0 × 10−10 cm3 s−1 at low temperatures, which increase to ~ 5.0 × 10−10 cm3 s−1 for temperatures higher than 200 K. In this case, our detailed modeling - taking into account the electronic and spin states – provides a rate that is higher than the one currently used by factor of approximately 2. Conclusions. These reactions were selected based on their inclusion of open-shell species with many degenerate electronic states, and, unexpectedly, the results obtained in the present detailed calculations provide values that differ by a factor of about 2–3 from the simpler classical capture method. We updated the sulphur network with these new rates and compare our results in the prototypical case of TMC1 (CP). We find a reasonable agreement between model predictions and observations with a sulphur depletion factor of 20 relative to the sulphur cosmic abundance. However, it is not possible to fit the abundances of all sulphur-bearing molecules better than a factor of 10 at the same chemical time.

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Linking the dust and chemical evolution: Taurus and Perseus

Cited by 9 publications

References 146 publications

NIKA2 observations of starless cores in Taurus and Perseus

NIKA2 observations of starless cores in Taurus and Perseus

Nitrogen fractionation in ammonia and its insights into nitrogen chemistry

Gas phase Elemental abundances in Molecular cloudS (GEMS)

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