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

Kód výsledku v 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>

Výsledek na webu

<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>

Jazyk výsledku

angličtina

Název v původním jazyce

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

Popis výsledku v původním jazyce

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.

Název v anglickém jazyce

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

Popis výsledku anglicky

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.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

—

Návaznosti

—

Rok uplatnění

2020

Kód důvěrnosti údajů

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

Název periodika

Astrophysical Journal

ISSN

0004-637X

e-ISSN

1538-4357

Svazek periodika

905

Číslo periodika v rámci svazku

2

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

16

Strana od-do

122

Kód UT WoS článku

000600810500001

EID výsledku v databázi Scopus

2-s2.0-85098887582