Solis

Lattanzi, Valerio; Alves, F. O.; Padovani, M.; Fontani, F.; Caselli, P.; Ceccarelli, C.; López-Sepulcre, A.; Favre, Cécile; Neri, R.; Chahine, L.; Vastel, C.; Evans, Lucy

doi:10.1051/0004-6361/202142736

Cited by 4 publications

(1 citation statement)

References 38 publications

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“…Thus, chemical processing might occur via ionization during earlier evolutionary phases. Indeed, numerous combined observational efforts, over much larger spatial scales, suggest that particle ionization rates might be quite high (>10 −15 s −1 ) during some portion of the protostellar phase (Ceccarelli et al 2014;Favre et al 2018;Cabedo et al 2023;Lattanzi et al 2023). This is supported by theoretical work that suggests cosmic rays could be generated via shocks within the jets (Padovani et al 2016;Gaches & Offner 2018).…”

Section: Disk Ionizationmentioning

confidence: 94%

The Carbon Isotopic Ratio and Planet Formation

Bergin,

Bosman,

Teague

et al. 2024

ApJ

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We present the first detection of 13CCH in a protoplanetary disk (TW Hya). Using observations of C2H, we measure CCH/13CCH = 65 ± 20 gas with a CO isotopic ratio of 12CO/13CO = 21 ± 5. The TW Hya disk exhibits a gas phase C/O that exceeds unity, and C2H is the tracer of this excess carbon. We confirm that the TW Hya gaseous disk exhibits two separate carbon isotopic reservoirs, as noted previously. We explore two theoretical solutions for the development of this dichotomy. One model represents TW Hya today with a protoplanetary disk exposed to a cosmic-ray ionization rate that is below interstellar as consistent with current estimates. We find that this model does not have sufficient ionization in cold (T < 40 K) layers to activate carbon isotopic fractionation. The second model investigates a younger TW Hya protostellar disk exposed to an interstellar cosmic-ray ionization rate. We find that the younger model has sources of ionization deeper in a colder disk that generates two independent isotopic reservoirs. One reservoir is 12C-enriched carried by methane/hydrocarbon ices, and the other is 13C-enriched carried by gaseous CO. The former potentially provides a source of methane/hydrocarbon ices to power the chemistry that generates the anomalously strong C2H emission in this (and other) disk systems in later stages. The latter provides a source of gaseous 13C-rich material to generate isotopic enrichments in forming giant planets, as recently detected in the super-Jupiter TYC 8998-760-1 b by Zhang et al.

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Section: Disk Ionizationmentioning

confidence: 94%

The Carbon Isotopic Ratio and Planet Formation

Bergin,

Bosman,

Teague

et al. 2024

ApJ

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A new analytic approach to infer the cosmic-ray ionization rate in hot molecular cores from HCO⁺, N₂H⁺, and CO observations

Luo,

Bisbas,

Padovani

et al. 2024

A&A

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The cosmic-ray ionization rate ($ is one of the key parameters in star formation, since it regulates the chemical and dynamical evolution of molecular clouds by ionizing molecules and determining the coupling between the magnetic field and gas. However, measurements of $ in dense clouds (e.g. H $) are difficult and sensitive to the model assumptions. The aim is to find a convenient analytic approach that can be used in high-mass star-forming regions (HMSFRs), especially for warm gas environments such as hot molecular cores (HMCs). We propose a new analytic approach to calculate $ through HCO$^+$, N$_2$H$^+$, and CO measurements. By comparing our method with various astrochemical models and with observations found in the literature, we identify the parameter space for which the analytic approach is applicable. Our method gives a good approximation, to within $50$<!PCT!>, of $ in dense and warm gas (e.g. H $, $T = 50, 100$\,K) for V 4$\,mag and $t at Solar metallicity. The analytic approach gives better results for higher densities. However, it starts to underestimate $ at low metallicity ($Z = 0.1Z_ when the value is too high ($ $ s$^ $). By applying our method to the OMC-2 FIR4 envelope and the L1157-B1 shock region, we find $ values of $(1.0 $ s$^ $ and $(2.2 $ s$^ $, consistent with those previously reported. We calculate $ toward a total of 82 samples in HMSFRs, finding that the average value of $ toward all HMC samples ($ = (7.4pm 5.0)times $) is more than an order of magnitude higher than the theoretical prediction of cosmic-ray attenuation models, favoring the scenario that locally accelerated cosmic rays in embedded protostars should be responsible for the observed high $ zeta_2$.

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Multiple chemical tracers finally unveil the intricate NGC 1333 IRAS 4A outflow system. FAUST XVI

Chahine,

Ceccarelli,

De Simone

et al. 2024

Monthly Notices of the Royal Astronomical Society

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The exploration of outflows in protobinary systems presents a challenging yet crucial endeavour, offering valuable insights into the dynamic interplay between protostars and their evolution. In this study, we examine the morphology and dynamics of jets and outflows within the IRAS 4A protobinary system. This analysis is based on ALMA observations of SiO(5–4), H2CO(30, 3–20, 3), and HDCO(41, 4–31, 3) with a spatial resolution of ∼150 au. Leveraging an astrochemical approach involving the use of diverse tracers beyond traditional ones has enabled the identification of novel features and a comprehensive understanding of the broader outflow dynamics. Our analysis reveals the presence of two jets in the redshifted emission, emanating from IRAS 4A1 and IRAS 4A2, respectively. Furthermore, we identify four distinct outflows in the region for the first time, with each protostar, 4A1 and 4A2, contributing to two of them. We characterise the morphology and orientation of each outflow, challenging previous suggestions of bends in their trajectories. The outflow cavities of IRAS 4A1 exhibit extensions of 10″ and 13″ with position angles (PA) of 0○ and -12○, respectively, while those of IRAS 4A2 are more extended, spanning 18″ and 25″ with PAs of 29○ and 26○. We propose that the misalignment of the cavities is due to a jet precession in each protostar, a notion supported by the observation that the more extended cavities of the same source exhibit lower velocities, indicating they may stem from older ejection events.

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Solis

Cited by 4 publications

References 38 publications

The Carbon Isotopic Ratio and Planet Formation

The Carbon Isotopic Ratio and Planet Formation

A new analytic approach to infer the cosmic-ray ionization rate in hot molecular cores from HCO⁺, N₂H⁺, and CO observations

Multiple chemical tracers finally unveil the intricate NGC 1333 IRAS 4A outflow system. FAUST XVI

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Solis

Cited by 4 publications

References 38 publications

The Carbon Isotopic Ratio and Planet Formation

The Carbon Isotopic Ratio and Planet Formation

A new analytic approach to infer the cosmic-ray ionization rate in hot molecular cores from HCO+, N2H+, and CO observations

Multiple chemical tracers finally unveil the intricate NGC 1333 IRAS 4A outflow system. FAUST XVI

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A new analytic approach to infer the cosmic-ray ionization rate in hot molecular cores from HCO⁺, N₂H⁺, and CO observations