The First Interferometric Measurements of NH2D/NH3 Ratio in Hot Corinos
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The First Interferometric Measurements of NH2D/NH3 Ratio in Hot Corinos. / Yamato, Yoshihide; Furuya, Kenji; Aikawa, Yuri; Persson, Magnus V.; Tobin, John J.; Jorgensen, Jes K.; Kama, Mihkel.
I: Astrophysical Journal, Bind 941, Nr. 1, 75, 01.12.2022.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - The First Interferometric Measurements of NH2D/NH3 Ratio in Hot Corinos
AU - Yamato, Yoshihide
AU - Furuya, Kenji
AU - Aikawa, Yuri
AU - Persson, Magnus V.
AU - Tobin, John J.
AU - Jorgensen, Jes K.
AU - Kama, Mihkel
PY - 2022/12/1
Y1 - 2022/12/1
N2 - The chemical evolution of nitrogen during star and planet formation is still not fully understood. Ammonia (NH3) is a key specie in the understanding of the molecular evolution in star-forming clouds and nitrogen isotope fractionation. In this paper, we present high-spatial-resolution observations of multiple emission lines of NH3 toward the protobinary system NGC1333 IRAS4A with the Karl G. Jansky Very Large Array. We spatially resolved the binary (hereafter, 4A1 and 4A2) and detected compact emission of NH3 transitions with high excitation energies (greater than or similar to 100 K) from the vicinity of the protostars, indicating the NH3 ice has sublimated at the inner hot region. The NH3 column density is estimated to be similar to 10(17)-10(18) cm(-2). We also detected two NH2D transitions, allowing us to constrain the deuterium fractionation of ammonia. The NH2D/NH3 ratios are as high as similar to 0.3-1 in both 4A1 and 4A2. From comparisons with the astrochemical models in the literature, the high NH2D/NH3 ratios suggest that the formation of NH3 ices mainly started in the prestellar phase after the formation of bulk water ice finished, and that the primary nitrogen reservoir in the star-forming cloud could be atomic nitrogen (or N atoms) rather than nitrogen-bearing species such as N-2 and NH3. The implications on the physical properties of IRAS4A's cores are discussed as well.
AB - The chemical evolution of nitrogen during star and planet formation is still not fully understood. Ammonia (NH3) is a key specie in the understanding of the molecular evolution in star-forming clouds and nitrogen isotope fractionation. In this paper, we present high-spatial-resolution observations of multiple emission lines of NH3 toward the protobinary system NGC1333 IRAS4A with the Karl G. Jansky Very Large Array. We spatially resolved the binary (hereafter, 4A1 and 4A2) and detected compact emission of NH3 transitions with high excitation energies (greater than or similar to 100 K) from the vicinity of the protostars, indicating the NH3 ice has sublimated at the inner hot region. The NH3 column density is estimated to be similar to 10(17)-10(18) cm(-2). We also detected two NH2D transitions, allowing us to constrain the deuterium fractionation of ammonia. The NH2D/NH3 ratios are as high as similar to 0.3-1 in both 4A1 and 4A2. From comparisons with the astrochemical models in the literature, the high NH2D/NH3 ratios suggest that the formation of NH3 ices mainly started in the prestellar phase after the formation of bulk water ice finished, and that the primary nitrogen reservoir in the star-forming cloud could be atomic nitrogen (or N atoms) rather than nitrogen-bearing species such as N-2 and NH3. The implications on the physical properties of IRAS4A's cores are discussed as well.
KW - DEUTERATED AMMONIA
KW - HYPERFINE STRUCTURE
KW - INTERSTELLAR ICES
KW - DENSE CORES
KW - SUBMILLIMETER
KW - ABUNDANCE
KW - ROTATION
KW - NITROGEN
KW - NH3
KW - PARAMETERS
U2 - 10.3847/1538-4357/ac9ea5
DO - 10.3847/1538-4357/ac9ea5
M3 - Journal article
VL - 941
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 1
M1 - 75
ER -
ID: 332118936