[en] The angular distributions of the ¹⁵N(³He,d)¹⁶O reaction were measured with the aim to determine the direct capture rate of the astrophysical reaction ¹⁵N(p, γ)¹⁶O by deducing asymptotic normalization coefficients (ANC). The ¹⁵N(p,γ)¹⁶O reaction is a part of the CNO cycle having importance in the nucleosynthesis of the N and O isotopes. The measurement was carried out on the cyclotron U120M of NPI CAS at the energy 25.74 MeV of ³He ions in a gas chamber containing the high purity ¹⁵N isotope. The preliminary results of corresponding spectroscopic factors and ANC's were used for the estimation of the S-factor for the direct capture ¹⁵N(p,γ)¹⁶O. Using the widths of the resonances E_R = 312 and 962 keV, the total S-factor was determined within the framework of the R-matrix approach

[en] The ¹⁵N(p,γ)¹⁶O reaction provides a path from the CN cycle to the CNO bi-cycle and CNO tri-cycle. The measured astrophysical factor for this reaction is dominated by resonant capture through two strong J^π=1^- resonances at E_R=312 and 962 keV and direct capture to the ground state. Asymptotic normalization coefficients (ANCs) for the ground and seven excited states in ¹⁶O were extracted from the comparison of experimental differential cross sections for the ¹⁵N(³He,d)¹⁶O reaction with distorted-wave Born approximation calculations. Using these ANCs and proton and α resonance widths determined from an R-matrix fit to the data from the ¹⁵N(p,α)¹²C reaction, we carried out an R-matrix calculation to obtain the astrophysical factor for the ¹⁵N(p,γ)¹⁶O reaction. The results indicate that the direct capture contribution was previously overestimated. We find the astrophysical factor to be S(0)=36.0±6.0 keV b, which is about a factor of 2 lower than the presently accepted value. We conclude that for every 2200±300 cycles of the main CN cycle one CN catalyst is lost due to this reaction

[en] We present the N₂H⁺ (J = 1 → 0) map of the Serpens South molecular cloud obtained as part of the CARMA Large Area Star Formation Survey. The observations cover 250 arcmin² and fully sample structures from 3000 AU to 3 pc with a velocity resolution of 0.16 km s^–1, and they can be used to constrain the origin and evolution of molecular cloud filaments. The spatial distribution of the N₂H⁺ emission is characterized by long filaments that resemble those observed in the dust continuum emission by Herschel. However, the gas filaments are typically narrower such that, in some cases, two or three quasi-parallel N₂H⁺ filaments comprise a single observed dust continuum filament. The difference between the dust and gas filament widths casts doubt on Herschel ability to resolve the Serpens South filaments. Some molecular filaments show velocity gradients along their major axis, and two are characterized by a steep velocity gradient in the direction perpendicular to the filament axis. The observed velocity gradient along one of these filaments was previously postulated as evidence for mass infall toward the central cluster, but these kind of gradients can be interpreted as projection of large-scale turbulence