# Astrophysics and Astronomy Commons™

## All Articles in Astrophysics and Astronomy

6,287 full-text articles. Page 184 of 190.

The Magellanic Clouds Survey: A Bridge To Nearby Galaxies, 2010 University of Massachusetts - Amherst

#### The Magellanic Clouds Survey: A Bridge To Nearby Galaxies, P Scowen, R Jansen, M Beasley, D Calzetti

##### Astronomy Department Faculty Publication Series

We outline to the community the value of a Magellanic Clouds Survey that consists of three components: I) a complete-area, high resolution, multi-band UV-near-IR broadband survey; II) a narrowband survey in 7 key nebular filters to cover a statistically significant sample of representative HII regions and a large-area, contiguous survey of the diffuse, warm ISM; and III) a comprehensive FUV spectroscopic survey of 1300 early-type stars. The science areas enabled by such a dataset are as follows: A) assessment of massive star feedback in both HII regions and the diffuse, warm ISM; B) completion of a comprehensive study of the ...

The Size Evolution Of Passive Galaxies: Observations From The Wide Field Camera 3 Early Release Science Program, 2010 University of Massachusetts - Amherst

#### The Size Evolution Of Passive Galaxies: Observations From The Wide Field Camera 3 Early Release Science Program, Ryan Jr, Mccarthy, Cohen, Yan, Hathi, Koekemoer, Rutkowski, Mechtley, Windhorst, O’Connell, Balick, Bond, Bushouse, D Calzetti

##### Astronomy Department Faculty Publication Series

We present results on the size evolution of passively evolving galaxies at 1 . z . 2 drawn from the Wide Field Camera 3 Early Release Science program. Our sample was constructed using an analog to the passive BzK selection criterion, which isolates galaxies with little or no on-going star formation at z & 1.5. We identify 30 galaxies in 40 arcmin2 to H < 25 mag. We supplement spectroscopic redshifts from the literature with photometric redshifts determined from the 15-band photometry from 0.22 . 8 ƒÊm. We determine effective radii from SLersic profile fits to the H-band image using an empirical PSF. We find that size evolution is a strong function of stellar mass, with the most massive (M 1011 M) galaxies undergoing the most rapid evolution from z 2 to the present. Parameterizing the size evolution as (1 + z)., we find a tentative scaling between and stellar mass of .1.8 + 1.4 log(M/109 M). We briefly discuss the implications of this result for our understanding of the dynamical evolution of the red galaxies.

Recommendations Of The Vao-Science Council, 2010 University of Massachusetts - Amherst

#### Recommendations Of The Vao-Science Council, G Fabbiano, D Calzetti

##### Astronomy Department Faculty Publication Series

No abstract provided.

Properties Of Compact 250 Μm Emission And H Ii Regions In M 33 (Herm33es)*, 2010 University of Massachusetts - Amherst

#### Properties Of Compact 250 Μm Emission And H Ii Regions In M 33 (Herm33es)*, S Verley, M Relaño, C Kramer, E Xilouris, M Boquien, D Calzetti

##### Astronomy Department Faculty Publication Series

Aims. Within the framework of the HERM33ES key program, using the high resolution and sensitivity of the Herschel photometric data, we study the compact emission in the Local Group spiral galaxy M 33 to investigate the nature of the compact SPIRE emission sources. We extracted a catalogue of sources at 250 μm in order to investigate the nature of this compact emission. Taking advantage of the unprecedented Herschel resolution at these wavelengths, we also focus on a more precise study of some striking Hα shells in the northern part of the galaxy. Methods. We present a catalogue of 159 compact ...

The Hubble Space Telescope Wide Field Camera 3 Early Release Science Data: Panchromatic Faint Object Counts From 0.2{2 Microns Wavelength, 2010 University of Massachusetts - Amherst

#### The Hubble Space Telescope Wide Field Camera 3 Early Release Science Data: Panchromatic Faint Object Counts From 0.2{2 Microns Wavelength, R Windhorst, S Cohen, N Hathi, P Mccarthy Jr, R Ryan, H Yan, I Baldry, S Driver, J Frogel, D Hill, L Kelvin, A Koekemoer, M Mechtley, R O'Connell, A Robotham, M Rutkowski, M Seibert, R Tuffs, B Balick, H Bond, H Bushouse, D Calzetti

##### Astronomy Department Faculty Publication Series

We describe the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) Early Re- lease Science (ERS) observations in the Great Observatories Origins Deep Survey (GOODS) South eld. The new WFC3 ERS data provide calibrated, drizzled mosaics in the mid-UV lters F225W, F275W, and F336W, as well as in the near-IR lters F098W (Ys), F125W (J), and F160W (H) in 1{2 HST orbits per lter. Together with the existing HST Advanced Camera for Surveys (ACS) GOODS-South mosaics in the BVi'z' lters, these panchromatic 10-band ERS data cover 40{50 square arcmin from from 0.2-1.7 m in ...

Nearby Galaxies With Spitzer, 2010 University of Massachusetts - Amherst

#### Nearby Galaxies With Spitzer, D Calzetti

##### Astronomy Department Faculty Publication Series

We review the main advances brought by the Spitzer Space Telescope in the field of nearby galaxies studies, concentrating on a few subject areas, including: (1) the physics of the Polycyclic Aromatic Hydrocarbons that generate the mid–infrared features between 3.5 ìm and 20 ìm; (2) the use of the mid– and far–infrared emission from galaxies as star formation rate indicators; and (3) the improvement of mid–infrared diagnostics to discriminate between thermal (star–formation)and non–thermal (AGN) emission in galaxies and galaxy centers.

Hubble Space Telescope Imaging Of Lyman Alpha Emission At Z = 4.41, 2010 University of Massachusetts - Amherst

#### Hubble Space Telescope Imaging Of Lyman Alpha Emission At Z = 4.41, S Finkelstein, S Cohen, R Windhorst, R Ryan, N Hathi, K Finkelstein, J Anderson, N Grogin, A Koekemoer, S Malhotra, M Mutchler, J Rhoads, P Mccarthy, R O’Connell, B Balick, H Bond, D Calzetti

##### Astronomy Department Faculty Publication Series

We present the highest redshift detections of resolved Ly emission, using Hubble Space Telescope/ACS F658N narrowband-imaging data taken in parallel with the Wide Field Camera 3 Early Release Science program in the GOODS CDF-S. We detect Ly emission from three spectroscopically confirmed z = 4.4 Ly emitting galaxies (LAEs), more than doubling the sample of LAEs with resolved Ly emission. Comparing the light distribution between the rest-frame ultraviolet continuum and narrowband images, we investigate the escape of Ly photons at high redshift. While our data do not support a positional offset between the Ly and rest-frame ultraviolet (UV) continuum ...

Exoptf Science Uniquely Enabled By Far-Ir Interferometry: Probing The Formation Of Planetary Systems, And Finding And Characterizing Exoplanets, 2010 University of Massachusetts Amherst

#### Exoptf Science Uniquely Enabled By Far-Ir Interferometry: Probing The Formation Of Planetary Systems, And Finding And Characterizing Exoplanets, D Leisawitz, T Armstrong, C Benderb, D Benford, D Calzetti

##### Astronomy Department Faculty Publication Series

By providing sensitive sub-arcsecond images and integral field spectroscopy in the 25 – 400 ìm wavelength range, a far-IR interferometer will revolutionize our understanding of planetary system formation, reveal otherwise-undetectable planets through the disk perturbations they induce, and spectroscopically probe the atmospheres of extrasolar giant planets in orbits typical of most of the planets in our solar system. The technical challenges associated with interferometry in the far-IR are greatly relaxed relative to those encountered at shorter wavelengths or when starlight nulling is required. A structurally connected far-IR interferometer with a maximum baseline length of 36 m can resolve the interesting spatial ...

Uv-Dropout Galaxies In The Goods-South Field From Wfc3 Early Release Science Observations, 2010 University of Massachusetts - Amherst

#### Uv-Dropout Galaxies In The Goods-South Field From Wfc3 Early Release Science Observations, N Hathi, R Ryan, S Cohen, H Yan, R Windhorst, P Mccarthy, R O'Connell, A Koekemoer, M Rutkowsk, B Balick, H Bond, D Calzetti

##### Astronomy Department Faculty Publication Series

We combine new high sensitivity ultraviolet (UV) imaging from the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) with existing deep HST/Advanced Camera for Surveys optical images from the Great Observatories Origins Deep Survey (GOODS) program to identify UV-dropouts, which are Lyman break galaxy (LBG) candidates at z sime 1-3. These new HST/WFC3 observations were taken over 50 arcmin2 in the GOODS-South field as a part of the Early Release Science program. The uniqueness of these new UV data is that they are observed in three UV/optical (WFC3 UVIS) channel filters (F225W, F275W, and ...

Structure And Evolution Of The Opacity Of Spiral Disks, 2010 University of Massachusetts - Amherst

#### Structure And Evolution Of The Opacity Of Spiral Disks, B Holwerda, R González, W Keel, D Calzetti

##### Astronomy Department Faculty Publication Series

The opacity of a spiral disk due to dust absorption influences every measurement we make of it in the UV and optical. Two separate techniques directly measure the total absorption by dust in the disk: calibrated distant galaxy counts and overlapping galaxy pairs. The main results from both so far are a semi-transparent disk with more opaque arms and a relation between surface brightness and disk opacity. In the Spitzer era, spectral energy distribution models of spiral disks add a new perspective on the role of dust in spiral disks. Combined with the overall opacity from galaxy counts, we can ...

Setting The Normalcy Level Of Hi Properties In Isolated Galaxies, 2010 University of Massachusetts - Amherst

#### Setting The Normalcy Level Of Hi Properties In Isolated Galaxies, D Espada, L Verdes-Montenegro, E Athanassoula, A Bosma, Wk Huchtmeier, S Leon, U Lisenfeld, J Sabater, J Sulentic, S Verley, Min Yun

##### Astronomy Department Faculty Publication Series

Studying the atomic gas (HI) properties of the most isolated galaxies is essential to quantify the effect that the environment exerts on this sensitive component of the interstellar medium. We observed and compiled HI data for a well defined sample of ∼ 800 galaxies in the Catalog of Isolated Galaxies, as part of the AMIGA project (Analysis of the ISM in Isolated GAlaxies, http://amiga.iaa.es), which enlarges considerably previous samples used to quantify the HI deficiency in galaxies located in denser environments. By studying the shape of 182 HI profiles, we revisited the usually accepted result that, independently of ...

Detection Of Oh+ And H2o+ Towards Orion Kl, 2010 University of Massachusetts - Amherst

#### Detection Of Oh+ And H2o+ Towards Orion Kl, M Gupta, P Rimmer, Jc Pearson, S Yu, E Herbst, N Marada, Ea Bergin, Da Neufeld, Gj Melnick, R Bachiller, W Baechtold, Ta Bell, Ga Blake, E Caux, C Ceccarelli, J Cernicharo, G Chattopadhyay, C Comito, S Cabrit, Nr Crockett, F Daniel, E Falgarone, Mc Diez-Gonzalez, Ml Dubernet, Nr Erickson, M Emprechtinger, P Encrenaz, M Gerin, Jj Gill, Tf Giesen, Jr Goicoechea, Pf Goldsmith, C Joblin, D Johnstone, Wd Langer, B Larsson, Wb Latter, Rh Lin, Dc Lis, R Lieseau, Sd Lord, Fw Maiwald, S Maret, Pg Martin, J Martin-Pintado, Km Menten, P Morris, Hsp Muller, Ja Murphy, Lh Nordh, M Olberg, V Ossenkopf, L Pagani, M Perault, Tg Phillips, R Plume, Sl Qin, M Salez, La Samoska, P Schilke, E Schlecht, R Szczerba, J Stutzki, N Trappe, Ffs Van Der Tak, C Vastel, S Wang, Hw Yorke, J Zmuidzinas, A Boogert, R Gusten, P Hartogh, N Honingh, A Karpov, J Kooi, Jm Krieg, R Schieder, P Zaal

##### Astronomy Department Faculty Publication Series

We report observations of the reactive molecular ions OH+, H2O+, and H3O+ towards Orion KL with Herschel/HIFI. All three N = 1-0 fine-structure transitions of OH+ at 909, 971, and 1033 GHz and both fine-structure components of the doublet ortho-H2O+ 111–000 transition at 1115 and 1139 GHz were detected; an upper limit was obtained for H3O+. OH+ and H2O+ are observed purely in absorption, showing a narrow component at the source velocity of 9 km s-1, and a broad blueshifted absorption similar to that reported ...

Westerbork Ultra-Deep Survey Of Hi At Z=0.2, 2010 University of Massachusetts - Amherst

#### Westerbork Ultra-Deep Survey Of Hi At Z=0.2, M Verheijen, B Deshev, J Van Gorkom, B Poggianti, A Chung, R Cybulski, Ks Dawarakanath, M Montero-Castano, G Morrison, D Schiminovich, A Szomoru, Min Yun

##### Astronomy Department Faculty Publication Series

In this contribution, we present some preliminary observational results from the completed ultra-deep survey of 21cm emission from neutral hydrogen at redshifts z=0.164-0.224 with the Westerbork Synthesis Radio Telescope. In two separate fields, a total of 160 individual galaxies has been detected in neutral hydrogen, with HI masses varying from 1.1x10^9 to 4.0x10^10 Msun. The largest galaxies are spatially resolved by the synthesized beam of 23x37 arcsec^2 while the velocity resolution of 19 km/s allowed the HI emission lines to be well resolved. The large scale structure in the surveyed volume ...

Is There Such A Thing As Quiet Sun?, 2010 University of Colorado, Boulder

#### Is There Such A Thing As Quiet Sun?, Mark Peter Rast

##### Astrophysical & Planetary Sciences Faculty Contributions

The Cycle 23–Cycle 24 minimum was deep and prolonged, similar to minima of the late 19th and early 20th centuries but quite different from those between the overlapping cycles of the early space age. This provides a unique opportunity to study the Sun at very low levels of magnetic activity. Here we examine the quiet Sun, defining it to be those portions of the Sun for which continuum intensity variations are dominated by thermal perturbations as op- posed to opacity fluctuations due to the presence of magnetic fields. We briefly present evidence that: (1) The expected thermal signature of ...

Modeling The Solar Irradiance Background Via Numerical Simulation, 2010 Universitá degli Studi di Roma “Tor Vergata”

#### Modeling The Solar Irradiance Background Via Numerical Simulation, B. Viticchié, M. Vantaggiato, F. Berrilli, D. Del Moro, V. Penza, E. Pietropaolo, M. Rast

##### Astrophysical & Planetary Sciences Faculty Contributions

Various small scale photospheric processes are responsible for spatial and temporal variations of solar emer- gent intensity. The contribution to total irradiance fluctua- tions of such small scale features is the solar irradiance back- ground. Here we examine the statistical properties of irradi- ance background computed via a n-body numerical scheme mimicking photospheric space-time correlations and cal- ibrated by means of IBIS/DST spectro-polarimetric data. Such computed properties are compared with experimen- tal results derived from the analysis of a VIRGO/SPM data. A future application of the model here presented could be the interpretation of stellar irradiance power spectra ...

2010 Solar And Space Physics Decadal Survey White Paper: Next Steps In Solar Spectral Irradiance Studies, 2010 University of Colorado, Boulder

#### 2010 Solar And Space Physics Decadal Survey White Paper: Next Steps In Solar Spectral Irradiance Studies, Mark P. Rast, Jerald W. Harder, Roberto Casini, Serena Criscuoli, Ilaria Ermolli, Juan Fontenla, Hanli Liu, Scott W. Mcintosh, Carolus J. Schrijver, Han Uitenbroek

##### Astrophysical & Planetary Sciences Faculty Contributions

Understanding the physical causes underlying solar spectral irradiance variations and the impact of these variations on terrestrial climate remain critical compelling challenges. On the solar side, the most fundamental unknown is the role of the “quiet-sun7 ,” a question brought into focus by spectral irradiance observations during the recent deep minimum, which show opposing trends in the infrared and ultraviolet portions of the spectrum (Harder et al. 2009). On the terrestrial side, while it is clear that the Sun played only a small role in late twentieth century warming, the signature of solar cycle variations in climate are now quite well ...

Pressure Support Versus Thermal Broadening In The Lyman Alpha Forest - Ii. Effects Of The Equation Of State On Transverse Structure, 2010 University of Massachusetts - Amherst

#### Pressure Support Versus Thermal Broadening In The Lyman Alpha Forest - Ii. Effects Of The Equation Of State On Transverse Structure, Ms Peeples, Dh Weinberg, R Dave, Ma Fardal, N Katz

##### Astronomy Department Faculty Publication Series

We examine the impact of gas pressure on the transverse coherence of high-redshift (2 ≤z≤ 4) Lyman α (Lyα) forest absorption along neighbouring lines of sight that probe the gas Jeans scale (projected separation Δrp≤ 500 h−1 kpc comoving, angular separation Δθ≲ 30 arcsec). We compare predictions from two smoothed particle hydrodynamics simulations that have different photoionization heating rates and thus different temperature–density relations in the intergalactic medium (IGM). We also compare spectra computed from the gas distributions to those computed from the pressureless dark matter. The coherence along neighbouring sightlines is markedly higher for the ...

Detection Of An Ultra-Bright Submillimeter Galaxy In The Subaru/Xmm-Newton Deep Field Using Aztec/Aste, 2010 University of Massachusetts - Amherst

#### Detection Of An Ultra-Bright Submillimeter Galaxy In The Subaru/Xmm-Newton Deep Field Using Aztec/Aste, S Ikarashi, K Kohno, Je Aguirre, I Aretxaga, V Arumugam, Je Austermann, Jj Bock, Cm Bradford, M Cirasuolo, L Earle, H Ezawa, H Furusawa, J Furusawa, J Glenn, B Hatsukade, Dh Hughes, D Iono, Rj Ivison, S Johnson, J Kamenetzky, R Kawabe, R Lupu, P Maloney, H Matsuhara, Pd Mauskopf, K Motohara, Ej Murphy, K Nakajima, K Nakanishi, Bj Naylor, Ht Nguyen, Ta Perera, Ks Scott, K Shimasaku, T Takagi, T Takata, Y Tamura, K Tanaka, T Tsukagoshi, Dj Wilner, Gw Wilson, Min Yun, J Zmuidzinas

##### Astronomy Department Faculty Publication Series

Abstract: We report the detection of an extremely bright ($\sim$34 mJy at 1100 $\mu$m and $\sim$73 mJy at 880 $\mu$m) submillimeter galaxy (SMG), AzTEC-ASTE-SXDF1100.001 (hereafter referred to as SXDF1100.001), discovered in 1100 $\mu$m observations of the Subaru/XMM-Newton Deep Field using AzTEC on ASTE. Subsequent CARMA 1300 $\mu$m and SMA 880 $\mu$m observations successfully pinpoint the location of SXDF1100.001 and suggest that it has two components, extended (FWHM of $\sim$4^{\prime\prime}) and compact (unresolved) ones. Z-Spec on CSO has also been used to obtain a wide band spectrum ...

Using 21 Cm Absorption In Small Impact Parameter Galaxy-Quasar Pairs To Probe Low-Redshift Damped And Sub-Damped Ly Alpha Systems, 2010 University of Massachusetts - Amherst

#### Using 21 Cm Absorption In Small Impact Parameter Galaxy-Quasar Pairs To Probe Low-Redshift Damped And Sub-Damped Ly Alpha Systems, S Borthakur, Tm Tripp, Min Yun, E Momjian, Jd Meiring, Dv Bowen, Dg York

##### Astronomy Department Faculty Publication Series

To search for low-redshift damped Lyα (DLA) and sub-DLA quasar absorbers, we have conducted a 21 cm absorption survey of radio-loud quasars at small impact parameters to foreground galaxies selected from the Sloan Digital Sky Survey (SDSS). Here we present the first results from this survey based on observations of SDSS J104257.58+074850.5 (z QSO = 2.66521), a quasar at an angular separation from a foreground galaxy (z gal = 0.03321) of 25 (1.7 kpc in projection). The foreground galaxy is a low-luminosity spiral with on-going star formation (0.004 M yr–1 kpc–2) and a ...

The Calibration Of Monochromatic Far-Infrared Star Formation Rate Indicators, 2010 University of Massachusetts Amherst

#### The Calibration Of Monochromatic Far-Infrared Star Formation Rate Indicators, D Calzetti, Sy Wu, S Hong, Rc Kennicutt, Jc Lee, Da Dale, Cw Engelbracht, L Van Zee, Bt Draine, Cn Hao, Kd Gordon, J Moustakas, Ej Murphy, M Regan, A Begum, M Block, J Dalcanton, J Funes, Ag De Paz, B Johnson, S Sakai, E Skillman, F Walter, D Weisz, B Williams, Y Wu

##### Astronomy Department Faculty Publication Series

Spitzer data at 24, 70, and 160 μm and ground-based Hα images are analyzed for a sample of 189 nearby star-forming and starburst galaxies to investigate whether reliable star formation rate (SFR) indicators can be defined using the monochromatic infrared dust emission centered at 70 and 160 μm. We compare recently published recipes for SFR measures using combinations of the 24 μm and observed Hα luminosities with those using 24 μm luminosity alone. From these comparisons, we derive a reference SFR indicator for use in our analysis. Linear correlations between SFR and the 70 μm and 160 μm luminosity are ...