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相关论文: Predicting reliable H$_2$ column density maps from…

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Column-density maps of molecular clouds are one of the most important observables in the context of molecular cloud- and star-formation (SF) studies. With the Herschel satellite it is now possible to determine the column density from dust…

星系天体物理 · 物理学 2015-03-04 N. Schneider , V. Ossenkopf , T. Csengeri , R. Klessen , C. Federrath , P. Tremblin , P. Girichidis , S. Bontemps , Ph. Andre

$Aims.$ We characterize the molecular-line emission of three clouds whose star-formation rates span one order of magnitude: California, Perseus, and Orion A. $Methods.$ We use stratified random sampling to select positions representing the…

星系天体物理 · 物理学 2023-11-29 M. Tafalla , A. Usero , A. Hacar

Characterizing the conversion factor between CO emission and column density of molecular hydrogen, X_CO, is crucial in studying the gaseous content of galaxies, its evolution, and relation to star formation. In most cases the conversion…

宇宙学与河外天体物理 · 物理学 2015-06-03 Robert Feldmann , Nickolay Y. Gnedin , Andrey V. Kravtsov

We present the first results on the diffuse transition clouds observed in [CII] line emission at 158 microns (1.9 THz) towards Galactic longitudes near 340deg (5 LOSs) and 20deg (11 LOSs) as part of the GOT C+ survey. Out of the total 146…

星系天体物理 · 物理学 2015-05-19 T. Velusamy , W. D. Langer , J. L. Pineda , P. F. Goldsmith , D. Li. , H. W. Yorke

Volume density is a key physical quantity controlling the evolution of the interstellar medium (ISM) and star formation, but it cannot be accessed directly by observations of molecular clouds. We aim at estimating the volume density…

星系天体物理 · 物理学 2025-05-15 Jan H. Orkisz , Jouni Kainulainen

ABRIDGED: Context: HI and CO large scale surveys of the Milky Way trace the diffuse atomic clouds and the dense shielded regions of molecular hydrogen clouds. However, until recently, we have not had spectrally resolved C+ surveys to…

星系天体物理 · 物理学 2015-06-18 W. D. Langer , T. Velusamy , J. L. Pineda , K. Willacy , P. F. Goldsmith

The most usual tracer of molecular gas is line emission from CO. However, the reliability of that tracer has long been questioned in environments different from the Milky Way. We study the relationship between H2 and CO abundances using a…

星系天体物理 · 物理学 2015-05-18 S. C. O. Glover , M. -M. Mac Low

This study presents a catalog of 8107 molecular clouds that covers the entire Galactic plane and includes 98% of the $^{12}$CO emission observed within $b\pm5^\circ$. The catalog was produced using a hierarchical cluster identification…

星系天体物理 · 物理学 2017-01-11 Marc-Antoine Miville-Deschênes , Norman Murray , Eve J. Lee

We characterize the column density probability distributions functions (PDFs) of the atomic hydrogen gas, HI, associated with seven Galactic molecular clouds (MCs). We use 21 cm observations from the Leiden/Argentine/Bonn Galactic HI Survey…

星系天体物理 · 物理学 2016-10-05 Nia Imara , Blakesley Burkhart

Infrared stellar photometry from 2MASS and spectral line imaging observations of 12CO and 13CO J = 1-0 line emission from the FCRAO 14m telescope are analysed to assess the variation of the CO abundance with physical conditions throughout…

星系天体物理 · 物理学 2015-06-15 F. Ripple , M. H. Heyer , R. Gutermuth , R. L. Snell , C. M. Brunt

We present a study of the cold atomic hydrogen (HI) content of molecular clouds simulated within the SILCC-Zoom project. We produce synthetic observations of HI at 21 cm including HI self-absorption (HISA) and observational effects. We find…

星系天体物理 · 物理学 2022-03-14 D. Seifried , H. Beuther , S. Walch , J. Syed , J. D. Soler , P. Girichidis , R. Wünsch

Previous attempts at segmenting molecular line maps of molecular clouds have focused on using position-position-velocity data cubes of a single line to separate the spatial components of the cloud. In contrast, wide field spectral imaging…

To complement the optical absorption-line survey of diffuse molecular gas in Paper I, we obtained and analyzed far ultraviolet H$_2$ and CO data on lines of sight toward stars in Cep OB2 and Cep OB3. Possible correlations between column…

天体物理学 · 物理学 2009-11-13 K. Pan , S. R. Federman , Y. Sheffer , B. -G. Andersson

We have obtained column density maps for an unbiased sample of 120 molecular clouds in the third quadrant of the Milky Way mid-plane (b$\le |5|^{\circ}$) within the galactic longitude range from 195$^{\circ}$ to 225$^{\circ}$, using the…

星系天体物理 · 物理学 2022-08-31 Yuehui Ma , Hongchi Wang , Miaomiao Zhang , Chen Wang , Shaobo Zhang , Yao Liu , Chong Li , Yuqing Zheng , Lixia Yuan , Ji Yang

The formation of molecular hydrogen (H$_2$) and carbon monoxide (CO) is sensitive to the volume and column density distribution of the turbulent interstellar medium. In this paper, we study H$_2$ and CO formation in a large set of…

星系天体物理 · 物理学 2019-01-23 P. R. Joshi , S. Walch , D. Seifried , S. C. O. Glover , S. D. Clarke , M. Weis

Using UV spectra obtained with FUSE, HST, and/or IUE, we determine interstellar column densities of 12CO, 13CO, and/or C_2 for ten Galactic sight lines with 0.37<E(B-V)<0.72. The N(CO)/N(H_2) ratio varies over a factor of 100 in this…

天体物理学 · 物理学 2009-05-29 P. Sonnentrucker , D. E. Welty , J. A. Thorburn , D. G. York

We present a wide-field $(60\arcmin \times 30\arcmin)$ study of a dense region within the Polaris Flare, hereafter referred to as the `Polaris molecular cloud', using $^{12}$CO, $^{13}$CO, and C$^{18}$O ($J=1-0$) observations at $20\arcsec$…

星系天体物理 · 物理学 2025-02-18 Tomomi Shimoikura , Kazuhito Dobashi , Fumitaka Nakamura , Kotomi Taniguchi

We have conducted OH 18 cm survey toward 141 molecular clouds in various environments, including 33 optical dark clouds, 98 Planck Galactic cold clumps (PGCCs) and 10 Spitzer dark clouds with the Arecibo telescope. The deviations from local…

星系天体物理 · 物理学 2020-12-23 Ningyu Tang , Di Li , Nannan Yue , Pei Zuo , Tie Liu , Gan Luo , Longfei Chen , Sheng-Li Qin , Yuefang Wu , Carl Heiles

We present and analyze deep Herschel/HIFI observations of the [CII] 158um, [CI] 609um, and [CI] 370um lines towards 54 lines-of-sight (LOS) in the Large and Small Magellanic clouds. These observations are used to determine the physical…

We present the second dust continuum data release in the Census of High- and Medium-mass Protostars (CHaMP), expanding the methodology trialed in Pitts et al. 2019 to the entire CHaMP survey area ($280^{\circ}<l<300^{\circ}$,…

星系天体物理 · 物理学 2021-08-25 Rebecca L. Pitts , Peter J. Barnes