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We present maps of the column densities of H$_2$O, CO$_2$, and CO ices towards the molecular cores B~35A, DC~274.2-00.4, BHR~59, and DC~300.7-01.0. These ice maps, probing spatial distances in molecular cores as low as 2200~AU, challenge…

星系天体物理 · 物理学 2017-03-06 J. A. Noble , H. J. Fraser , K. M. Pontoppidan , A. M. Craigon

Complex organic molecules (COMs) are thought to be the precursors of pre-biotic molecules and are observed in many protostellar sources. For this paper we studied the formation of COMs during star formation and their evolution in the…

Recent observations have revealed significant variations in the abundances of gas- and ice-phase molecules in galaxies with different luminosities and types. In order to discuss the physical origins of these variations, we incorporate gas-…

星系天体物理 · 物理学 2025-12-16 K. Bekki , K. Furuya , T. Shimonishi

To study the demographics of interstellar ices in the Central Molecular Zone (CMZ) of the Milky Way, we obtain near-infrared spectra of $109$ red point sources using NASA IRTF/SpeX at Maunakea. We select the sample from near- and…

Solid-phase photo-processes involving icy dust grains greatly affect the chemical evolution of the interstellar medium by leading to the formation of complex organic molecules and by inducing photodesorption. So far, the focus of laboratory…

The origin and evolution of organic molecules represent a pivotal issue in the fields of astrobiology and astrochemistry, potentially shedding light on the origins of life. The James Webb Space Telescope (JWST), with its exceptional…

星系天体物理 · 物理学 2024-09-09 Lei Lei , Lei Feng , Yi-Zhong Fan

We present results from our spectroscopic study, using the Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope, designed to identify massive young stellar objects (YSOs) in the Galactic Center (GC). Our sample of 107 YSO…

We investigate the molecular evolution and D/H abundance ratios that develop as star formation proceeds from a dense-cloud core to a protostellar core, by solving a gas-grain reaction network applied to a 1-D radiative hydrodynamic model…

星系天体物理 · 物理学 2015-06-11 Yuri Aikawa , Valentine Wakelam , Franck Hersant , Robin T. Garrod , Eric Herbst

Luminosity bursts in young FU Orionis-type stars warm up the surrounding disks of gas and dust, thus inflicting changes on their morphological and chemical composition. In this work, we aim at studying the effects that such bursts may have…

Aims: Ices in dense star-forming cores contain the bulk of volatile molecules apart from H2 and thus represent a large fraction of dark cloud chemistry budget.To directly constrain the freeze-out profile of CO, the formation route of CO2…

天体物理学 · 物理学 2009-11-11 K. M. Pontoppidan

We report the detection of several molecular gas-phase and ice absorption features in three photometrically-selected young stellar object (YSO) candidates in the central 280 pc of the Milky Way. Our spectra, obtained with the Infrared…

During massive star formation, dense gas undergoes chemical evolution, producing both simple and complex organic molecules (COMs) characteristic of hot molecular cores. How this evolution depends on protostellar physical properties remains…

星系天体物理 · 物理学 2025-10-31 D. Gigli , P. Gorai , C. Y. Law , J. C. Tan , M. Bonfand , T. Rahman , Y. Zhang , K. Taniguchi , R. Fedriani , Z. Telkamp , V. Rosero , G. Cosentino

Molecular oxygen has been the subject of many observational searches as chemical models predicted it to be a reservoir of oxygen. Although it has been detected in two regions of the interstellar medium, its rarity is a challenge for…

星系天体物理 · 物理学 2019-06-04 V. Wakelam , M. Ruaud , P. Gratier , I. A. Bonnell

This work aims to utilize the increased sensitivity and resolution of the JWST to quantify the HDO/H$_{2}$O ratio in ices toward young stellar objects (YSOs) and to determine if the HDO/H$_{2}$O ratios measured in the gas phase toward…

The evolution of disks around Young Stellar Objects (YSOs) is deeply affected by the YSOs ultraviolet (UV) radiation field especially in the 500-1100 \AA\ spectral range. The two dominant processes are; the photo-dissociation of H_2…

太阳与恒星天体物理 · 物理学 2015-05-30 Andreas Pedersen , Ana Ines Gómez de Castro

We present Spitzer IRAC images that indicate the presence of cavities cut into the dense outer envelope surrounding very young pre-main sequence stars. These young stellar objects (YSOs) characterized by an outflow represent the earliest…

天体物理学 · 物理学 2007-11-28 Jonathan P. Seale , Leslie W. Looney

We investigate the evolution of molecular abundance in quiescent protoplanetary disks which are presumed to be around weak-line T Tauri stars. In the region of surface density less than $10^2$ g cm$^{-2}$ (distance from the star $\gtrsim…

天体物理学 · 物理学 2009-10-30 Y. Aikawa , T. Umebayashi , T. Nakano , S. M. Miyama

The temperature and density structure of molecular cloud cores are the most important physical quantities that determine the course of the protostellar collapse and the properties of the stars they form. Nevertheless, density profiles often…

Recent observations show that the CO gas abundance, relative to H$_2$, in many 1-10 Myr old protoplanetary disks may be heavily depleted, by a factor of 10-100 compared to the canonical interstellar medium value of 10$^{-4}$. When and how…

地球与行星天体物理 · 物理学 2020-03-11 Ke Zhang , Kamber R. Schwarz , Edwin A. Bergin

We investigate molecular evolution in a star-forming core that is initially a hydrostatic starless core and collapses to form a low-mass protostar. The results of a one-dimensional radiation-hydrodynamics calculation are adopted as a…

天体物理学 · 物理学 2009-11-13 Yuri Aikawa , Valentine Wakelam , Robin T. Garrod , Eric Herbst