Physical Conditions of Gas Components in Debris Disks of 49 Ceti and HD 21997

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F20%3A00553635" target="_blank" >RIV/67985815:_____/20:00553635 - isvavai.cz</a>

Result on the web

<a href="https://doi.org/10.3847/1538-4357/abc5bb" target="_blank" >https://doi.org/10.3847/1538-4357/abc5bb</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.3847/1538-4357/abc5bb" target="_blank" >10.3847/1538-4357/abc5bb</a>

Result language

angličtina

Original language name

Physical Conditions of Gas Components in Debris Disks of 49 Ceti and HD 21997

Original language description

Characterization of the gas component in debris disks is of fundamental importance for understanding their origin. To address this goal, we have conducted non-LTE (local thermodynamic equilibrium) analyses of the rotational spectral lines of CO including those of rare isotopologues ((CO)-C-13 and (CO)-O-18) that have been observed toward the gaseous debris disks of 49 Ceti and HD 21997 with the Atacama Large Millimeter/submillimeter Array (ALMA) and the Atacama Compact Array (ACA). The analyses have been carried out for a wide range of H-2 density, and the observed line intensities are found to be reproduced as long as the H-2 density is higher than 10(3) cm(-3). The CO column density and the gas temperature are evaluated to be (1.8-5.9) x 10(17) cm(-2) and 8-11 K for 49 Ceti and (2.6-15) x 10(17) cm(-2) and 8-12 K for HD 21997, respectively, where the H-2 collision is assumed for the rotational excitation of CO. The results do not change significantly even if electron collision is considered. Thus, CO molecules can be excited under environments containing no H-2 or a small number of H-2 molecules, even where collisions with CO, C, O, and C+ would make an important contribution to the CO excitation in addition to H-2. Meanwhile, our result does not rule out the case of abundant H-2 molecules. The low gas temperature observed in the debris disks is discussed in terms of inefficient heating by interstellar and stellar UV radiation.

Czech name

—

Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10308 - Astronomy (including astrophysics,space science)

Project

—

Continuities

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Publication year

2020

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Astrophysical Journal

ISSN

0004-637X

e-ISSN

1538-4357

Volume of the periodical

905

Issue of the periodical within the volume

2

Country of publishing house

GB - UNITED KINGDOM

Number of pages

16

Pages from-to

122

UT code for WoS article

000600810500001

EID of the result in the Scopus database

2-s2.0-85098887582