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To understand physical properties of the interstellar medium (ISM) on various scales, we investigate it at parsec resolution on the kiloparsec scale. Here, we report on the sub-kpc scale Gas Density Histogram (GDH) of the Milky Way. The GDH…

The recent detection of gas-phase methanol (CH$_3$OH) lines in the disc of TW Hya by Walsh et al. provided the first observational constraints on the complex O-bearing organic content in protoplanetary discs. The emission has a ring-like…

太阳与恒星天体物理 · 物理学 2017-03-14 S. Yu. Parfenov , D. A. Semenov , Th. Henning , A. S. Shapovalova , A. M. Sobolev , R. Teague

Protoplanetary disks around young stars are the sites of planet formation. While the dust mass can be estimated using standard methods, determining the gas mass - and thus the amount of material available to form giant planets - has proven…

太阳与恒星天体物理 · 物理学 2017-09-13 Leon Trapman , Anna Miotello , Mihkel Kama , Ewine F. van Dishoeck , Simon Bruderer

Due to our vantage point in the disk of the Galaxy, its 3D structure is not directly accessible. However, knowing the spatial distribution, e.g. of atomic and molecular hydrogen gas is of great importance for interpreting and modelling…

星系天体物理 · 物理学 2023-09-26 Laurin Söding , Philipp Mertsch , Vo Hong Minh Phan

The Central Molecular Zone (CMZ) at the center of our Galaxy is the best template to study star formation processes under extreme conditions, similar to those in high-redshift galaxies. We observed on-the-fly maps of para-H$_{2}$CO…

星系天体物理 · 物理学 2016-11-09 K. Immer , J. Kauffmann , T. Pillai , A. Ginsburg , K. M. Menten

The total mass estimate of molecular clouds suffers from the uncertainty in the H$_2$-CO conversion factor, the so-called $X_{\rm CO}$ factor, which is used to convert the $^{12}$CO (1--0) integrated intensity to the H$_2$ column density.…

The Large Magellanic Cloud (LMC), the closest star forming galaxy with low metallicity, provides an ideal laboratory to study star formation in such an environment. The classical dense molecular gas thermometer NH3 is rarely available in a…

星系天体物理 · 物理学 2017-03-22 X. D. Tang , C. Henkel , C. -H. R. Chen , K. M. Menten , R. Indebetouw , X. W. Zheng , J. Esimbek , J. J. Zhou , Y. Yuan , D. L. Li , Y. X. He

Chemical diversity of the gas in low-mass protostellar cores is widely recognized. In order to explore its origin, a survey of chemical composition toward 36 Class 0/I protostars in the Perseus molecular cloud complex, which are selected in…

We present an analysis of archival ISO observations of pure-rotational lines of H2 in three pointings in the central 3 parsecs of the Galaxy: toward the Southwest region and Northeast region of the Galactic center Circumnuclear Disk, and…

星系天体物理 · 物理学 2017-12-13 E. A. C. Mills , A. Togi , M. Kaufman

CH2 transitions between 68 and 71 GHz were first detected toward the Orion-KL and W51 Main SFRs. Given their upper level energies of 225 K, they were thought to arise in dense, hot molecular cores near newly formed stars. However, this has…

星系天体物理 · 物理学 2021-03-10 A. M. Jacob , K. M. Menten , Y. Gong , P. Bergman , M. Tiwari , S. Bruenken , A. O. H. Olofsson

Local star-forming galaxies show properties that are thought to differ from galaxies in the early Universe. Among them, the ionizing stellar populations and the gas geometry make the recipes designed to derive chemical abundances from…

星系天体物理 · 物理学 2021-04-07 E. Pérez-Montero , R. Amorín , J. Sánchez Almeida , J. M. Vílchez , R. García-Benito , C. Kehrig

(Abridged) We study the response of the gas to energetic processes associated with high-mass star formation and compare it with studies on low- and intermediate-mass young stellar objects (YSOs) using the same methods. The far-IR line…

We present the results of N2H+(1-0) observations of 35 dense molecular cloud cores from the northern and southern hemispheres where massive stars and star clusters are formed. Line emission has been detected in 33 sources, for 28 sources…

天体物理学 · 物理学 2009-11-07 L. Pirogov , I. Zinchenko , P. Caselli , L. E. B. Johansson , P. C. Myers

We have started a measurement campaign of numerous methanol isotopologs in low-lying torsional states in order to provide extensive line lists for radio astronomical observations from an adequate spectroscopic model and to investigate how…

Stars form within molecular clouds, so characterizing the physical states of molecular clouds is key in understanding the process of star formation. Cloud structure and stability is frequently assessed using metrics including the virial…

星系天体物理 · 物理学 2022-07-20 Theo J. O'Neill , Remy Indebetouw , Alberto D. Bolatto , Suzanne C. Madden , Tony Wong

Upcoming facilities such as the Herschel Space Observatory or ALMA will deliver a wealth of molecular line observations of young stellar objects (YSOs). Based on line fluxes, chemical abundances can then be estimated by radiative transfer…

太阳与恒星天体物理 · 物理学 2009-07-22 Simon Bruderer , Steven D. Doty , Arnold O. Benz

The abundance of cold molecular gas plays a crucial role in models of galaxy evolution. While deep spectroscopic surveys of CO emission lines have been a primary tool for measuring this abundance, the difficulty of these observations has…

星系天体物理 · 物理学 2022-03-30 Ryan P. Keenan , Garrett K. Keating , Daniel P. Marrone

The cosmic-ray ionization rate (CRIR, $\zeta_2$) is one of the key parameters controlling the formation and destruction of various molecules in molecular clouds. However, the current most commonly used CRIR tracers, such as H$_3^+$, OH$^+$,…

星系天体物理 · 物理学 2023-04-07 Gan Luo , Zhiyu Zhang , Thomas G. Bisbas , Di Li , Ping Zhou , Ningyu Tang , Junzhi Wang , Pei Zuo , Nannan Yue

The H3+ ion plays a key role in the chemistry of dense interstellar gas clouds where stars and planets are forming. The low temperatures and high extinctions of such clouds make direct observations of H3+ impossible, but lead to large…

星系天体物理 · 物理学 2015-06-04 Floris van der Tak