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Observation of CO emission around asymptotic giant branch (AGB) stars is the primary method to determine gas mass-loss rates. While radiative transfer models have shown that molecular levels of CO can become mildly inverted, causing maser…

Solar and Stellar Astrophysics · Physics 2021-10-04 W. H. T. Vlemmings , T. Khouri , D. Tafoya

Recent targeted studies of associated HI absorption in radio galaxies are starting to map out the location, and potential cosmological evolution, of the cold gas in the host galaxies of Active Galactic Nuclei (AGN). The observed 21 cm…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 J. R. Allison , E. M. Sadler , S. J. Curran , S. N. Reeves

Using a radiative transfer code (DUSTY) parameters of the circumstellar dust shells of 15 hot post-AGB stars have been derived. Combining the optical, near and far-infrared (ISO, IRAS) data of the stars, we have reconstructed their spectral…

Astrophysics · Physics 2007-05-23 G. Sarkar Nee Gauba , M. Parthasarathy

The presence, distribution and kinematics of atomic neutral hydrogen in the central regions of galaxies can be traced by the HI 21~cm line observed in absorption. Depending only on the strength of the radio continuum, the associated…

Astrophysics of Galaxies · Physics 2024-12-11 Raffaella Morganti

We present and interpret observations of atomic and molecular gas toward the southern elliptical galaxy NGC 1316 (Fornax A), a strong double-lobe radio source with a disturbed optical morphology that includes numerous shells and loops. The…

The energetic feedback that is generated by radio jets in active galactic nuclei (AGNs) has been suggested to be able to produce fast outflows of atomic hydrogen (HI) gas that can be studied in absorption at high spatial resolution. We have…

Astrophysics of Galaxies · Physics 2018-09-19 R. Schulz , R. Morganti , K. Nyland , Z. Paragi , E. K. Mahony , T. Oosterloo

Atomic hydrogen (HI) dominates the mass of the cold interstellar medium, undergoing thermal condensation to form molecular gas and fuel star formation. Kinematically colder HI components, identified via kinematic decomposition of HI 21 cm…

Many aspects of the evolutionary phase in which Asymptotic Giant Branch stars (AGB stars) are in transition to become Planetary Nebulae (PNe) are still poorly understood. An important question is how the circumstellar envelopes of AGB stars…

Solar and Stellar Astrophysics · Physics 2019-08-14 L. Cerrigone , K. M. Menten , T. Kaminski

The HIFI instrument on board the Herschel Space Observatory has been used to observe interstellar nitrogen hydrides along the sight-line towards G10.6-0.4 in order to improve our understanding of the interstellar chemistry of nitrogen. We…

The atomic hydrogen gas (HI) disk in the outer region (beyond ~10 kpc from the centre) of Milky Way can provide valuable information about the structure of the dark matter halo. The recent 3-D thickness map of the outer HI disk from the all…

Astrophysics of Galaxies · Physics 2011-02-11 Kanak Saha , Evan S. Levine , Chanda J. Jog , Leo Blitz

This paper reports a detection of the 30 micron emission feature from the C-rich Asymptotic Giant Branch (AGB) star IRAS 03313+6058 based on the ISO-SWS observation. Modeling of the spectral energy distribution shows that this emission…

Astrophysics · Physics 2019-08-17 B. W. Jiang , R. Szczerba , S. Deguchi

We present 1.4 GHz HI absorption line observations towards the starburst in NGC2146, made with the VLA and MERLIN. The HI gas has a rotating disk/ring structure with column densities between 6 and 18 x 10(21) atoms cm(-2). The HI absorption…

Astrophysics · Physics 2007-05-23 A. Tarchi , A. Greve , A. B. Peck , N. Neininger , K. A. Wills , A. Pedlar , U. Klein

We present Chandra snapshot observations for a sample of 7 sources selected from the Arecibo OH megamaser (OHM) survey at z~0.13-0.22 and with far-infrared luminosities in excess of 10^{11} L_sun. In contrast with the known H2O megamasers,…

Astrophysics · Physics 2009-11-13 C. Vignali , W. N. Brandt , A. Comastri , J. Darling

We have used the Robert C. Byrd Green Bank Telescope to perform the most sensitive search to date for neutral atomic hydrogen (HI) in the circumstellar envelope (CSE) of the carbon star IRC+10216. Our observations have uncovered a low…

Solar and Stellar Astrophysics · Physics 2015-06-23 L. D. Matthews , E. Gerard , T. Le Bertre

Very sensitive 21cm HI measurements have been made at several locations around the Local Group galaxy M31 using the Green Bank Telescope (GBT) at an angular resolution of 9.1', with a 5$\sigma$ detection level of $\rm{N_{HI} = 3.9 \times…

Astrophysics of Galaxies · Physics 2016-01-27 Spencer A. Wolfe , Felix J. Lockman , D. J. Pisano

We have studied the small scale distribution of atomic hydrogen (HI) using 21-cm absorption spectra against multiple-component background radio continuum sources from the 21-SPONGE survey and the Millennium Arecibo Absorption Line Survey.…

Observations of the neutral atomic hydrogen (HI) in the nuclear starburst galaxy NGC 4945 with MeerKAT are presented. We find a large amount of halo gas, previously missed by HI observations, accounting for 6.8% of the total HI mass. This…

The atomic hydrogen (HI) properties of star-forming galaxies in the local Universe are known to correlate with other galaxy properties via the ``HI scaling relations''. The redshift evolution of these relations serves as an important…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-14 Apurba Bera , Nissim Kanekar , Jayaram N. Chengalur , Jasjeet S. Bagla

Aims. We aim to resolve the spatial and kinematic sub-structures in five detached-shell sources to provide detailed constraints for hydrodynamic models that describe the formation and evolution of the shells. Methods. We use observations of…

Solar and Stellar Astrophysics · Physics 2024-07-03 M. Maercker , E. De Beck , T. Khouri , W. H. T. Vlemmings , J. Gustafsson , H. Olofsson , D. Tafoya , F. Kerschbaum , M. Lindqvist

The optical spectrum of the broad-line radio galaxy Arp 102B has been monitored for more than thirteen years to investigate the nature of the source of its broad, double-peaked hydrogen Balmer emission lines. The shape of the lines varied…