Browsing by Keyword "ISM: molecules"
Now showing items 1-20 of 29
-
C2absorption-line diagnostics of diffuse interstellar clouds
(Oxford University Press (OUP), 2002)The excitation of the diatomic carbon molecule in diffuse interstellar clouds is discussed for a cloud with large density fluctuations of small linear filling factor along the line of sight. Possible implications for the ... -
Complex Organic Molecules During Low-Mass Star Formation: Pilot Survey Results
(IOP Publishing, 2014)Complex organic molecules (COMs) are known to be abundant toward some low-mass young stellar objects (YSOs), but how these detections relate to typical COM abundance are not yet understood. We aim to constrain the frequency ... -
Dense Cores in Perseus: The Influence of Stellar Content and Cluster Environment
(American Astronomical Society, 2009)We present the chemistry, temperature, and dynamical state of a sample of 193 dense cores or core candidates in the Perseus Molecular cloud and compare the properties of cores associated with young stars and clusters with ... -
Detection of HCO+ towards Cygnus OB2 No. 12
(Oxford University Press (OUP), 2000)HCO+ has been detected for the first time towards the star Cygnus OB2 No. 12 through emission of the 1−0 rotational transition at 89GHz. The CO(J=2−1) transition has also been observed. The observations are consistent with ... -
Direct Observation of a Sharp Transition to Coherence in Dense Cores
(American Astronomical Society, 2010)We present \(NH_3\) observations of the B5 region in Perseus obtained with the Green Bank Telescope. The map covers a region large enough \((\sim 11'×14')\) that it contains the entire dense core observed in previous dust ... -
Discovery of Candidate H2O Disk Masers in Active Galactic Nuclei and Estimations of Centripetal Accelerations
(IOP Publishing, 2009)Based on spectroscopic signatures, about one-third of known H2O maser sources in active galactic nuclei (AGNs) are believed to arise in highly inclined accretion disks around central engines. These “disk maser candidates” ... -
The Discovery of H2O Maser Emission in Seven AGN and at High Velocities in the Circinus Galaxy
(IOP Publishing, 2002)We report the discovery of H2O maser emission at 1.35 cm wavelength in seven active galactic nuclei (at distances up to < 80 Mpc) during a survey conducted at the 70-m diameter antenna of the NASA Deep Space Network near ... -
Discovery of Water Maser Emission in Eight AGNs with 70 m Antennas of NASA’s Deep Space Network
(IOP Publishing, 2006)We report the discovery of water maser emission in eight active galactic nuclei (AGN) with the 70-m NASA Deep Space Network (DSN) antennas at Tidbinbilla, Australia and Robledo, Spain. The positions of the newly discovered ... -
Discovery of Water Maser Emission in Five AGNs and a Possible Correlation Between Water Maser and Nuclear 2–10 keV Luminosities
(IOP Publishing, 2006)We report the discovery of water maser emission in five active galactic nuclei (AGN) with the 100-m Green Bank Telescope (GBT). The positions of the newly discovered masers, measured with the VLA, are consistent with the ... -
Fine‐Structure Excitation of C + and Si + by Atomic Hydrogen
(IOP Publishing, 2005)We present calculations of cross sections for fine-structure excitation in collisions of carbon and silicon ions in the 2P state with atomic hydrogen in the ground state. The results are based on accurate calculations of ... -
First Detection of c-C3H2 in a Circumstellar Disk
(IOP Publishing, 2013)We report the first detection of c-C3H2 in a circumstellar disk. The c-C3H2 J = 6-5 line (217.882 GHz) is detected and imaged through Atacama Large Millimeter Array (ALMA) Science Verification observations toward the disk ... -
G11.92–0.61-MM2: A bonafide massive prestellar core?
(IOP Publishing, 2014)Core accretion models of massive star formation require the existence of stable massive starless cores, but robust observational examples of such objects have proven elusive. We report subarcsecond-resolution Submillimeter ... -
A Green Bank Telescope Search for Water Masers in Nearby Active Galactic Nuclei
(IOP Publishing, 2004)Using the Green Bank Telescope, we have conducted a survey for 1.3 cm water maser emission toward the nuclei of nearby active galaxies, the most sensitive large survey for H2O masers to date. Among 145 galaxies observed, ... -
H2 excitation in turbulent interstellar clouds
(Oxford University Press (OUP), 2005)We discuss the observational differences between lines of sight that intercept a group of turbulent dissipative structures and lines of sight that cross less-active regions. Using time-dependent calculations we show that ... -
H3+ in Diffuse Interstellar Gas
(Oxford University Press (OUP), 2000)A model is constructed of the material in front of the star Cygnus OB2 no. 12 in which dense cores are embedded in diffuse clumps of gas. The model reproduces the measured abundances of Graphic C2 and CO, and predicts a ... -
Hydrated sulphuric acid in dense molecular clouds
(Oxford University Press (OUP), 2003)We consider sulphur depletion in dense molecular clouds, and suggest hydrated sulphuric acid, H2SO4 · nH2O, as a component of interstellar dust in icy mantles. We discuss the formation of hydrated sulphuric acid in collapsing ... -
Indirect Ultraviolet Photodesorption from CO:N2 Binary Ices — An Efficient Grain-Gas Process
(IOP Publishing, 2013)Ultraviolet (UV) ice photodesorption is an important non-thermal desorption pathway in many interstellar environments that has been invoked to explain observations of cold molecules in disks, clouds, and cloud cores. ... -
Inferring the Composition of Super-Jupiter Mass Companions of Pulsars with Radio Line Spectroscopy
(American Astronomical Society, 2017)We propose using radio line spectroscopy to detect molecular absorption lines (such as OH at 1.6-1.7 GHz) before and after the total eclipse of black widow (BW) and other short orbital period binary pulsars with low mass ... -
Infrared Spectroscopic Survey of The Quiescent Medium of Nearby Clouds. I. Ice Formation and Grain Growth in Lupus
(IOP Publishing, 2013)Infrared photometry and spectroscopy (1-25 um) of background stars reddened by the Lupus molecular cloud complex are used to determine the properties of the grains and the composition of the ices before they are incorporated ... -
Line Imaging of Orion KL at 865 μm with the Submillimeter Array
(IOP Publishing, 2005)We present the first submm (865 µm) imaging spectral line survey at one arcsecond resolution conducted with the Submillimeter Array toward Orion-KL. Within the two × two GHz bandpasses (lower and upper sidebands, 337.2–339.2GHz ...