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Full-Text Articles in Astrophysics and Astronomy
Swas Observations Of Water In Molecular Outflows, J Franklin, Ronald L. Snell, Mj Kaufman, Gj Melnick, Da Neufeld, Dj Hollenbach, Ea Bergin
Swas Observations Of Water In Molecular Outflows, J Franklin, Ronald L. Snell, Mj Kaufman, Gj Melnick, Da Neufeld, Dj Hollenbach, Ea Bergin
Astronomy Department Faculty Publication Series
We present detections of the ground-state 110→ 101 transition of ortho-H2O at 557 GHz in 18 molecular outflows based on data from the Submillimeter Wave Astronomy Satellite (SWAS). These results are combined with ground-based observations of the J = 1–0 transitions of 12CO and 13CO obtained at the Five College Radio Astronomy Observatory (FCRAO). Data from Infrared Space Observatory (ISO) for a subset of the outflows are also discussed. Assuming that the SWAS water-line emission originates from the same gas traced by CO emission, we find that the outflowing …
Large-Scale Structure Of The Molecular Gas In Taurus Revealed By High Linear Dynamic Range Spectral Line Mapping, Pf Goldsmith, M Heyer, Gopal Narayanan, Ronald L. Snell, D Li, C Brunt
Large-Scale Structure Of The Molecular Gas In Taurus Revealed By High Linear Dynamic Range Spectral Line Mapping, Pf Goldsmith, M Heyer, Gopal Narayanan, Ronald L. Snell, D Li, C Brunt
Astronomy Department Faculty Publication Series
We report the results of a 100 deg2 survey of the Taurus molecular cloud region in 12CO and 13CO J = 1→ 0. The image of the cloud in each velocity channel includes 3 × 106 Nyquist-sampled pixels on a 20'' grid. The high sensitivity and large spatial dynamic range of the maps reveal a very complex, highly structured cloud morphology, including filaments, cavities, and rings. The axes of the striations seen in the 12CO emission from relatively diffuse gas are aligned with the direction of the magnetic field. We have developed a statistical …
The Incidence Of Highly Obscured Star-Forming Regions In Sings Galaxies, Mkm Prescott, Rc Kennicutt, Gj Bendo, Ba Buckalew, D Calzetti, Cw Engelbracht, Kd Gordon, Dj Hollenbach, Jc Lee, J Moustakas, Da Dale, G Helou, Th Jarrett, Ej Murphy, Jdt Smith, S Akiyama, Ml Sosey
The Incidence Of Highly Obscured Star-Forming Regions In Sings Galaxies, Mkm Prescott, Rc Kennicutt, Gj Bendo, Ba Buckalew, D Calzetti, Cw Engelbracht, Kd Gordon, Dj Hollenbach, Jc Lee, J Moustakas, Da Dale, G Helou, Th Jarrett, Ej Murphy, Jdt Smith, S Akiyama, Ml Sosey
Astronomy Department Faculty Publication Series
Using the new capabilities of Spitzer and extensive multiwavelength data from SINGS, it is now possible to study the infrared properties of star formation in nearby galaxies down to scales equivalent to large H II regions. We are therefore able to determine what fraction of large, infrared-selected star-forming regions in normal galaxies are highly obscured and address how much of the star formation we miss by relying solely on the optical portion of the spectrum. Employing a new empirical method for deriving attenuations of infrared-selected star-forming regions, we investigate the statistics of obscured star formation on 500 pc scales in …
Star Formation In Ngc 5194 (M51a). Ii. The Spatially Resolved Star Formation Law, Rc Kennicutt, D Calzetti, F Walter, G Helou, Dj Hollenbach, L Armus, G Bendo, Da Dale, Bt Draine, Cw Engelbracht, Kd Gordon, Mkm Prescott, Mw Regan, Md Thornley, C Bot, E Brinks, E De Blok, D De Mello, M Meyer, J Moustakas, Ej Murphy, K Sheth, Jdt Smith
Star Formation In Ngc 5194 (M51a). Ii. The Spatially Resolved Star Formation Law, Rc Kennicutt, D Calzetti, F Walter, G Helou, Dj Hollenbach, L Armus, G Bendo, Da Dale, Bt Draine, Cw Engelbracht, Kd Gordon, Mkm Prescott, Mw Regan, Md Thornley, C Bot, E Brinks, E De Blok, D De Mello, M Meyer, J Moustakas, Ej Murphy, K Sheth, Jdt Smith
Astronomy Department Faculty Publication Series
We have studied the relationship between the star formation rate (SFR), surface density, and gas surface density in the spiral galaxy M51a (NGC 5194), using multiwavelength data obtained as part of the Spitzer Infrared Nearby Galaxies Survey (SINGS). We introduce a new SFR index based on a linear combination of Hα emission-line and 24 μm continuum luminosities, which provides reliable extinction-corrected ionizing fluxes and SFR densities over a wide range of dust attenuations. The combination of these extinction-corrected SFR densities with aperture synthesis H I and CO maps has allowed us to probe the form of the spatially resolved star …
Star Formation And Feedback In Smoothed Particle Hydrodynamic Simulations - I. Isolated Galaxies, G Stinson, A Seth, N Katz, J Wadsley, F Governato, T Quinn
Star Formation And Feedback In Smoothed Particle Hydrodynamic Simulations - I. Isolated Galaxies, G Stinson, A Seth, N Katz, J Wadsley, F Governato, T Quinn
Astronomy Department Faculty Publication Series
We present an analysis of star formation and feedback recipes appropriate for galactic smoothed particle hydrodynamics simulations. Using an isolated Milky Way-like galaxy, we constrain these recipes based on well-established observational results. Our star formation recipe is based on that of Katz with the additional inclusion of physically motivated supernova feedback recipes. We propose a new feedback recipe in which Type II supernovae are modelled using an analytical treatment of blastwaves. With this feedback mechanism and a tuning of other star formation parameters, the star formation in our isolated Milky Way-like galaxy follows the slope and normalization of the observed …
Water Absorption From Line-Of-Sight Clouds Toward W49a, R Plume, Mj Kaufman, Da Neufeld, Ronald L. Snell, Dj Hollenbach, Pf Goldsmith, J Howe, Ea Bergin, Gj Melnick, F Bensch
Water Absorption From Line-Of-Sight Clouds Toward W49a, R Plume, Mj Kaufman, Da Neufeld, Ronald L. Snell, Dj Hollenbach, Pf Goldsmith, J Howe, Ea Bergin, Gj Melnick, F Bensch
Astronomy Department Faculty Publication Series
We have observed six clouds along the line of sight toward W49A using the Submillimeter Wave Astronomy Satellite and several ground-based observatories. The ortho-H2O 110 → 101 and OH (1665 and 1667 MHz) transitions are observed in absorption, whereas the low-J CO, 13CO, and C18O lines, as well as the [C I] 3P1-3P0 transition, are seen in emission. The emission lines allow us to determine the gas density (n ~ 1500-3000 cm-3) and CO column densities [N(CO) ~ 7.9 …
A Survey Of 557 Ghz Water Vapor Emission In The Ngc 1333 Molecular Cloud, Ea Bergin, Mj Kaufman, Gj Melnick, Ronald L. Snell, Je Howe
A Survey Of 557 Ghz Water Vapor Emission In The Ngc 1333 Molecular Cloud, Ea Bergin, Mj Kaufman, Gj Melnick, Ronald L. Snell, Je Howe
Astronomy Department Faculty Publication Series
Using NASA's Submillimeter Wave Astronomy Satellite (SWAS), we have examined the production of water in quiescent and shocked molecular gas through a survey of the 556.936 GHz 110-101 transition of ortho-H2O in the NGC 1333 molecular core. These observations reveal broad emission lines associated with the IRAS 2, IRAS 4, IRAS 7, and HH 7-11 outflows. Toward three positions we detect narrow (Δv ~ 2-3 km s-1) emission lines clearly associated with the ambient gas. The SWAS observations, with a resolution of ~4', are supplemented with observations from the Infrared …
Star Formation In Bright-Rimmed Clouds. I. Millimeter And Submillimeter Molecular Line Surveys, Ch De Vries, Gopal Narayanan, Ronald L. Snell
Star Formation In Bright-Rimmed Clouds. I. Millimeter And Submillimeter Molecular Line Surveys, Ch De Vries, Gopal Narayanan, Ronald L. Snell
Astronomy Department Faculty Publication Series
We present the results of the first detailed millimeter and submillimeter molecular line survey of bright-rimmed clouds, observed at FCRAO in the CO (J = 1 → 0), C18O (J = 1 → 0), HCO+ (J = 1 → 0), H13CO+ (J = 1 → 0), and N2H+ (J = 1 → 0) transitions, and at the Heinrich Hertz Telescope in the CO (J = 2 → 1), HCO+ (J = 3 → 2), HCO+ (J = 4 → 3), H …
Sensitive Limits On The Water Abundance In Cold Low-Mass Molecular Cores, Ea Bergin, Ronald L. Snell
Sensitive Limits On The Water Abundance In Cold Low-Mass Molecular Cores, Ea Bergin, Ronald L. Snell
Astronomy Department Faculty Publication Series
We present Submillimeter Wave Astronomy Satellite observations of water vapor in two cold starless clouds, B68 and core D in ρ Ophiuchi. Sensitive nondetections of the 110-101 transition of o-H2O are reported for each source. Both molecular cores have been previously examined by detailed observations that have characterized the physical structure. Using these rather well-defined physical properties and a Monte Carlo radiation transfer model, we have removed one of the largest uncertainties from the abundance calculation and set the lowest water abundance limit to date in cold low-mass molecular cores. These limits are x(o-H …
High-Redshift Galaxies In Cold Dark Matter Models, Dh Weinberg, L Hernquist, N Katz
High-Redshift Galaxies In Cold Dark Matter Models, Dh Weinberg, L Hernquist, N Katz
Astronomy Department Faculty Publication Series
We use hydrodynamic cosmological simulations to predict the star formation properties of high-redshift galaxies (z = 2-6) in five variants of the inflationary cold dark matter scenario, paying particular attention to z = 3, the redshift of the largest "Lyman break galaxy" (LBG) samples. Because we link the star formation timescale to the local gas density, the rate at which a galaxy forms stars is governed mainly by the rate at which it accretes cooled gas from the surrounding medium. At z = 3, star formation in most of the simulated galaxies is steady on ~200 Myr timescales, and …
Embedded Stellar Clusters In The W3/W4/W5 Molecular Cloud Complex, Jm Carpenter, Mh Heyer, Ronald L. Snell
Embedded Stellar Clusters In The W3/W4/W5 Molecular Cloud Complex, Jm Carpenter, Mh Heyer, Ronald L. Snell
Astronomy Department Faculty Publication Series
We analyze the embedded stellar content in the vicinity of the W3/W4/W5 H II regions using the FCRAO Outer Galaxy 12CO (1-0) Survey, the IRAS Point Source Catalog, published radio continuum surveys, and new near-infrared and molecular-line observations. Thirty-four IRAS point sources are identified that have far-infrared colors characteristic of embedded star forming regions, and we have obtained K' mosaics and 13CO (1-0) maps for 32 of them. Ten of the IRAS sources are associated with an OB star and 19 with a stellar cluster, although three OB stars are not identified with a cluster. Half of the …