145 citations · 394 across the 13 of their papers we have counts for
10 papers
Nuclear spin ratios of deuterated ammonia in prestellar cores. LAsMA observations of H-MM1 and Oph D
Jorma Harju, Jaime E. Pineda, Olli Sipilä +6
We determine the ortho/para ratios of NH2D and NHD2 in two dense, starless cores, where their formation is supposed to be dominated by gas-phase reactions, which, in turn, is predi…
Combined model for , , and spin-state chemistry in molecular clouds
O. Sipilä, L. Colzi, E. Roueff +3
We present a new gas-grain chemical model for the combined isotopic fractionation of carbon and nitrogen in molecular clouds, in which the isotope chemistry of carbon and nitrogen…
A Survey of Deuterated Ammonia in the Cepheus Star-Forming Region L1251
Maria Galloway-Sprietsma, Yancy L. Shirley, James Di Francesco +4
Understanding the chemical processes during starless core and prestellar core evolution is an important step in understanding the initial stages of star and disk formation. This pr…
Nitrogen fractionation towards a pre-stellar core traces isotope-selective photodissociation
Silvia Spezzano, Paola Caselli, Olli Sipilä +1
Isotopologue abundance ratios are important to understand the evolution of astrophysical objects and ultimately the origins of a planetary system like our own. Being nitrogen a fun…
Effect of grain size distribution and size-dependent grain heating on molecular abundances in starless and pre-stellar cores
O. Sipilä, B. Zhao, P. Caselli
We present a new gas-grain chemical model to constrain the effect of grain size distribution on molecular abundances in starless and pre-stellar cores. We introduce grain-size depe…
Carbon isotopic fractionation in molecular clouds
L. Colzi, O. Sipilä, E. Roueff +2
C-fractionation has been studied from a theoretical point of view with different models of time-dependent chemistry, including both isotope-selective photodissociation and low-temp…