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203. Dissecting Galaxy Colors with GALEX , SDSS, and Spitzer

Author

Johnson, B. D., primary, Schiminovich, D., additional, Seibert, M., additional, Treyer, M. A., additional, Charlot, S., additional, Heckman, T. M., additional, Martin, D. C., additional, Salim, S., additional, Kauffmann, G., additional, Bianchi, L., additional, Donas, J., additional, Friedman, P. G., additional, Lee, Y.-W., additional, Madore, B. F., additional, Milliard, B., additional, Morrissey, P., additional, Neff, S. G., additional, Rich, R. M., additional, Szalay, A. S., additional, Forster, K., additional, Barlow, T. A., additional, Conrow, T., additional, Small, T., additional, and Wyder, T. K., additional

Published
2006
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204. Star Formation in the Nearby Universe: The Ultraviolet and Infrared Points of View

Author

Iglesias‐Paramo, J., primary, Buat, V., additional, Takeuchi, T. T., additional, Xu, K., additional, Boissier, S., additional, Boselli, A., additional, Burgarella, D., additional, Madore, B. F., additional, Gil de Paz, A., additional, Bianchi, L., additional, Barlow, T. A., additional, Byun, Y.‐I., additional, Donas, J., additional, Forster, K., additional, Friedman, P. G., additional, Heckman, T. M., additional, Jelinski, P. N., additional, Lee, Y.‐W., additional, Malina, R. F., additional, Martin, D. C., additional, Milliard, B., additional, Morrissey, P. F., additional, Neff, S. G., additional, Rich, R. M., additional, Schiminovich, D., additional, Seibert, M., additional, Siegmund, O. H. W., additional, Small, T., additional, Szalay, A. S., additional, Welsh, B. Y., additional, and Wyder, T. K., additional

Published
2006
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208. GALEX Ultraviolet Observations of the Interacting Galaxy NGC 4438 in the Virgo Cluster

Author

Boselli, A., primary, Boissier, S., additional, Cortese, L., additional, Gil de Paz, A., additional, Buat, V., additional, Iglesias-Paramo, J., additional, Madore, B. F., additional, Barlow, T., additional, Bianchi, L., additional, Byun, Y.-I., additional, Donas, J., additional, Forster, K., additional, Friedman, P. G., additional, Heckman, T. M., additional, Jelinsky, P., additional, Lee, Y.-W., additional, Malina, R., additional, Martin, D. C., additional, Milliard, B., additional, Morrissey, P., additional, Neff, S., additional, Rich, R. M., additional, Schiminovich, D., additional, Seibert, M., additional, Siegmund, O., additional, Small, T., additional, Szalay, A. S., additional, Welsh, B., additional, and Wyder, T. K., additional

Published
2005
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209. The GALEX Ultraviolet Luminosity Function of the Cluster of Galaxies A1367

Author

Cortese, L., primary, Boselli, A., additional, Gavazzi, G., additional, Iglesias-Paramo, J., additional, Madore, B. F., additional, Barlow, T., additional, Bianchi, L., additional, Byun, Y.-I., additional, Donas, J., additional, Forster, K., additional, Friedman, P. G., additional, Heckman, T. M., additional, Jelinsky, P., additional, Lee, Y.-W., additional, Malina, R., additional, Martin, D. C., additional, Milliard, B., additional, Morrissey, P., additional, Neff, S., additional, Rich, R. M., additional, Schiminovich, D., additional, Siegmund, O., additional, Small, T., additional, Szalay, A. S., additional, Treyer, M. A., additional, Welsh, B., additional, and Wyder, T. K., additional

Published
2005
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210. Testing the Empirical Relation between Ultraviolet Color and Attenuation of Galaxies

Author

Seibert, Mark, primary, Martin, D. Christopher, additional, Heckman, Timothy M., additional, Buat, Veronique, additional, Hoopes, Charles, additional, Barlow, T., additional, Bianchi, L., additional, Byun, Y.-I., additional, Donas, J., additional, Forster, K., additional, Friedman, P. G., additional, Jelinsky, P., additional, Lee, Y.-W., additional, Madore, B. F., additional, Malina, R., additional, Milliard, B., additional, Morrissey, P., additional, Neff, S., additional, Rich, R. M., additional, Schiminovich, D., additional, Siegmund, O., additional, Small, T., additional, Szalay, A. S., additional, Welsh, B., additional, and Wyder, T. K., additional

Published
2005
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211. GALEX Observations of the Sloan Digital Sky Survey: A Comparison

Author

Seibert, Mark, primary, Budavári, Tamás, additional, Rhee, Jaehyon, additional, Rey, Soo-Chang, additional, Schiminovich, David, additional, Salim, Samir, additional, Martin, D. Christopher, additional, Szalay, Alex S., additional, Forster, Karl, additional, Rich, R. Michael, additional, Barlow, T., additional, Bianchi, L., additional, Byun, Y.-I., additional, Donas, J., additional, Friedman, P. G., additional, Heckman, T. M., additional, Jelinsky, P., additional, Lee, Y.-W., additional, Madore, B. F., additional, Malina, R., additional, Milliard, B., additional, Morrissey, P., additional, Neff, S., additional, Siegmund, O., additional, Small, T., additional, Welsh, B., additional, and Wyder, T. K., additional

Published
2005
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212. Ultraviolet Emission from Stellar Populations within Tidal Tails: Catching the Youngest Galaxies in Formation?

Author

Neff, S. G., primary, Thilker, D. A., additional, Seibert, M., additional, de Paz, A. Gil, additional, Bianchi, L., additional, Schiminovich, D., additional, Martin, D. C., additional, Madore, B. F., additional, Rich, R. M., additional, Barlow, T. A., additional, Byun, Y.-I., additional, Donas, J., additional, Forster, K., additional, Friedman, P. G., additional, Heckman, T. M., additional, Jelinsky, P. N., additional, Lee, Y.-W., additional, Malina, R. F., additional, Milliard, B., additional, Morrissey, P., additional, Siegmund, O. H. W., additional, Small, T., additional, Szalay, A. S., additional, Welsh, B. Y., additional, and Wyder, T. K., additional

Published
2005
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213. Dust Attenuation in the Nearby Universe: A Comparison between Galaxies Selected in the Ultraviolet and in the Far-Infrared

Author

Buat, V., primary, Iglesias-Páramo, J., additional, Seibert, M., additional, Burgarella, D., additional, Charlot, S., additional, Martin, D. C., additional, Xu, C. K., additional, Heckman, T. M., additional, Boissier, S., additional, Boselli, A., additional, Barlow, T., additional, Bianchi, L., additional, Byun, Y.-I., additional, Donas, J., additional, Forster, K., additional, Friedman, P. G., additional, Jelinski, P., additional, Lee, Y.-W., additional, Madore, B. F., additional, Malina, R., additional, Milliard, B., additional, Morissey, P., additional, Neff, S., additional, Rich, M., additional, Schiminovitch, D., additional, Siegmund, O., additional, Small, T., additional, Szalay, A. S., additional, Welsh, B., additional, and Wyder, T. K., additional

Published
2005
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214. Galaxy Evolution Explorer Ultraviolet Color-Magnitude Relations and Evidence of Recent Star Formation in Early-Type Galaxies

Author

Yi, S. K., primary, Yoon, S.-J., additional, Kaviraj, S., additional, Deharveng, J.-M., additional, Rich, R. M., additional, Salim, S., additional, Boselli, A., additional, Lee, Y.-W., additional, Ree, C. H., additional, Sohn, Y.-J., additional, Rey, S.-C., additional, Lee, J.-W., additional, Rhee, J., additional, Bianchi, L., additional, Byun, Y.-I., additional, Donas, J., additional, Friedman, P. G., additional, Heckman, T. M., additional, Jelinsky, P., additional, Madore, B. F., additional, Malina, R., additional, Martin, D. C., additional, Milliard, B., additional, Morrissey, P., additional, Neff, S., additional, Schiminovich, D., additional, Siegmund, O., additional, Small, T., additional, Szalay, A. S., additional, Jee, M. J., additional, Kim, S.-W., additional, Barlow, T., additional, Forster, K., additional, Welsh, B., additional, and Wyder, T. K., additional

Published
2005
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215. The GALEX VIMOS-VLT Deep Survey Measurement of the Evolution of the 1500 Å Luminosity Function

Author

Arnouts, S., primary, Schiminovich, D., additional, Ilbert, O., additional, Tresse, L., additional, Milliard, B., additional, Treyer, M., additional, Bardelli, S., additional, Budavari, T., additional, Wyder, T. K., additional, Zucca, E., additional, Le Fèvre, O., additional, Martin, D. C., additional, Vettolani, G., additional, Adami, C., additional, Arnaboldi, M., additional, Barlow, T., additional, Bianchi, L., additional, Bolzonella, M., additional, Bottini, D., additional, Byun, Y.-I., additional, Cappi, A., additional, Charlot, S., additional, Contini, T., additional, Donas, J., additional, Forster, K., additional, Foucaud, S., additional, Franzetti, P., additional, Friedman, P. G., additional, Garilli, B., additional, Gavignaud, I., additional, Guzzo, L., additional, Heckman, T. M., additional, Hoopes, C., additional, Iovino, A., additional, Jelinsky, P., additional, Le Brun, V., additional, Lee, Y.-W., additional, Maccagni, D., additional, Madore, B. F., additional, Malina, R., additional, Marano, B., additional, Marinoni, C., additional, McCracken, H. J., additional, Mazure, A., additional, Meneux, B., additional, Merighi, R., additional, Morrissey, P., additional, Neff, S., additional, Paltani, S., additional, Pellò, R., additional, Picat, J. P., additional, Pollo, A., additional, Pozzetti, L., additional, Radovich, M., additional, Rich, R. M., additional, Scaramella, R., additional, Scodeggio, M., additional, Seibert, M., additional, Siegmund, O., additional, Small, T., additional, Szalay, A. S., additional, Welsh, B., additional, Xu, C. K., additional, Zamorani, G., additional, and Zanichelli, A., additional

Published
2005
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216. The GALEX -VVDS Measurement of the Evolution of the Far-Ultraviolet Luminosity Density and the Cosmic Star Formation Rate

Author

Schiminovich, D., primary, Ilbert, O., additional, Arnouts, S., additional, Milliard, B., additional, Tresse, L., additional, Le Fèvre, O., additional, Treyer, M., additional, Wyder, T. K., additional, Budavári, T., additional, Zucca, E., additional, Zamorani, G., additional, Martin, D. C., additional, Adami, C., additional, Arnaboldi, M., additional, Bardelli, S., additional, Barlow, T., additional, Bianchi, L., additional, Bolzonella, M., additional, Bottini, D., additional, Byun, Y.-I., additional, Cappi, A., additional, Contini, T., additional, Charlot, S., additional, Donas, J., additional, Forster, K., additional, Foucaud, S., additional, Franzetti, P., additional, Friedman, P. G., additional, Garilli, B., additional, Gavignaud, I., additional, Guzzo, L., additional, Heckman, T. M., additional, Hoopes, C., additional, Iovino, A., additional, Jelinsky, P., additional, Le Brun, V., additional, Lee, Y.-W., additional, Maccagni, D., additional, Madore, B. F., additional, Malina, R., additional, Marano, B., additional, Marinoni, C., additional, McCracken, H. J., additional, Mazure, A., additional, Meneux, B., additional, Morrissey, P., additional, Neff, S., additional, Paltani, S., additional, Pellò, R., additional, Picat, J. P., additional, Pollo, A., additional, Pozzetti, L., additional, Radovich, M., additional, Rich, R. M., additional, Scaramella, R., additional, Scodeggio, M., additional, Seibert, M., additional, Siegmund, O., additional, Small, T., additional, Szalay, A. S., additional, Vettolani, G., additional, Welsh, B., additional, Xu, C. K., additional, and Zanichelli, A., additional

Published
2005
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217. Star Formation Triggering Mechanisms in Dwarf Galaxies: The Far-Ultraviolet, H-alpha, and HI Morphology of Holmberg II

Author

Stewart, S. G., Fanelli, M. N., Byrd, G. G., Hill, J. K., Westpfahl, D. J., Cheng, K. P., O'Connell, R. W., Roberts, M. S., Neff, S. G., Smith, A. M., Stecher, T. P., Stewart, S. G., Fanelli, M. N., Byrd, G. G., Hill, J. K., Westpfahl, D. J., Cheng, K. P., O'Connell, R. W., Roberts, M. S., Neff, S. G., Smith, A. M., and Stecher, T. P.

Abstract

Far-UV (FUV), H-alpha, and HI observations of dwarf galaxy Holmberg II are used to trace the interaction between sites of massive star formation and the neutral and ionized components of the surrounding ISM. The data emphasize the importance of local conditions in regulating star formation from evidence such as massive stars inside ionized shells, compact HII regions surrounding aging clusters, and stars formed in chains of progressing age. Large-scale triggering by HI shells is supported by observations of progenitor populations as well as secondary sites of star formation associated with their dense rims. Analysis of the energy available from massive stars inside HI shells indicates energy deposited into the ISM from supernovae and stellar winds is sufficient to account for the HI morphology. Ages of individual star forming regions are derived using B, H-alpha, and FUV photometry. The distribution of ages is reconciled with the HI morphology, showing a clear preference of young regions for areas of dense HI and old regions for HI voids. Global kinematical properties may also play a role in the star formation process since differences in the rotation characteristics of the neutral gas disk correlate with differences in triggering mechanisms., Comment: 24 Pages, 20 Figures, to appear in ApJ

Published
1999

218. The Emergence of the Modern Universe: Tracing the Cosmic Web

Author

Shull, J. M., Savage, B. D., Morse, J. A., Neff, S. G., Clarke, J. T., Heckman, T., Kinney, A. L., Jenkins, E. B., Dupree, A. K., Baum, S. A., Hasan, H., Shull, J. M., Savage, B. D., Morse, J. A., Neff, S. G., Clarke, J. T., Heckman, T., Kinney, A. L., Jenkins, E. B., Dupree, A. K., Baum, S. A., and Hasan, H.

Abstract

This is the report of the Ultraviolet-Optical Working Group (UVOWG) commissioned by NASA to study the scientific rationale for new missions in ultraviolet/optical space astronomy approximately ten years from now, when the Hubble Space Telescope (HST) is de-orbited. The UVOWG focused on a scientific theme, The Emergence of the Modern Universe, the period from redshifts z = 3 to 0, occupying over 80% of cosmic time and beginning after the first galaxies, quasars, and stars emerged into their present form. We considered high-throughput UV spectroscopy (10-50x throughput of HST/COS) and wide-field optical imaging (at least 10 arcmin square). The exciting science to be addressed in the post-HST era includes studies of dark matter and baryons, the origin and evolution of the elements, and the major construction phase of galaxies and quasars. Key unanswered questions include: Where is the rest of the unseen universe? What is the interplay of the dark and luminous universe? How did the IGM collapse to form the galaxies and clusters? When were galaxies, clusters, and stellar populations assembled into their current form? What is the history of star formation and chemical evolution? Are massive black holes a natural part of most galaxies? A large-aperture UV/O telescope in space (ST-2010) will provide a major facility in the 21st century for solving these scientific problems. The UVOWG recommends that the first mission be a 4m aperture, SIRTF-class mission that focuses on UV spectroscopy and wide-field imaging. In the coming decade, NASA should investigate the feasibility of an 8m telescope, by 2010, with deployable optics similar to NGST. No high-throughput UV/Optical mission will be possible without significant NASA investments in technology, including UV detectors, gratings, mirrors, and imagers., Comment: Report of UV/O Working Group to NASA, 72 pages, 13 figures, Full document with postscript figures available at http://casa.colorado.edu/~uvconf/UVOWG.html

Published
1999

220. Far-Ultraviolet Color Gradients in Early-Type Galaxies

Author

Ohl, R. G., O'Connell, R. W., Bohlin, R. C., Collins, N. R., Dorman, B., Fanelli, M. N., Neff, S. G., Roberts, M. S., Smith, A. M., Stecher, T. P., Ohl, R. G., O'Connell, R. W., Bohlin, R. C., Collins, N. R., Dorman, B., Fanelli, M. N., Neff, S. G., Roberts, M. S., Smith, A. M., and Stecher, T. P.

Abstract

We discuss far-UV (1500 A) surface photometry and FUV-B color profiles for 8 E/S0 galaxies from images taken with the Ultraviolet Imaging Telescope, primarily during the Astro-2 mission. In three cases, the FUV radial profiles are more consistent with an exponential than a de Vaucouleurs function, but there is no other evidence for the presence of a disk or of young, massive stars. In all cases except M32 the FUV-B color becomes redder at larger radii. There is a wide range of internal radial FUV-B color gradients. However, we find no correlation between the FUV-B color gradients and internal metallicity gradients based on Mg absorption features. We conclude that metallicity is not the sole parameter controlling the "UV upturn component" in old populations., Comment: 11 pages; tar.gz file includes LaTeX text file, 3 PostScript figures. Paper to be published in ApJ Letters

Published
1998
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221. The Hot Stars of Old Open Clusters: M67, NGC 188 and NGC6791

Author

Landsman, W., Bohlin, R. C., Neff, S. G., O'Connell, R. W., Roberts, M. S., Smith, A. M., Stecher, T. P., Landsman, W., Bohlin, R. C., Neff, S. G., O'Connell, R. W., Roberts, M. S., Smith, A. M., and Stecher, T. P.

Abstract

We analyze ultraviolet (~1500 A) images of the old open clusters M67, NGC 188, and NGC 6791 obtained with Ultraviolet Imaging Telescope (UIT) during the second flight of the Astro observatory in March 1995. Twenty stars are detected on the UIT image of M67, including 11 blue stragglers, seven white dwarf candidates, and the yellow giant -- white dwarf binary S1040. The ultraviolet photometry of the blue stragglers F90 (S975) and F131 (S1082) suggests that these stars have hot subluminous companions. We present a semi-empirical integrated ultraviolet spectrum of M67, and show that the blue stragglers dominate the integrated spectrum at wavelengths shorter than 2600 A. The number of white dwarfs in M67 is roughly consistent with the number expected from white dwarf cooling models. Eight candidate sdB/sdO stars are detected in NGC 6791, and two are detected in NGC 188. The luminosity range 1.10 < log L/Lsun < 1.27, derived from the ultraviolet photometry of the six sdB candidates, is consistent with theoretical models of metal-rich hot horizontal branch (HB) stars. The fraction of hot HB stars in both NGC 6791 and NGC 188 is about 30%, implying that the integrated spectra of both clusters should show a UV turnup at least as strong as that observed in any elliptical galaxy., Comment: 34 pages incl. 6 postscript figures, accepted for publication in AJ

Published
1998
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222. R&D on the Geant4 Radioactive Decay Physics.

Author

Hauf, S., Hoffmann, D. H. H., Lang, P., Neff, S., Kuster, M., Batič, M., Pia, M. G., Bell, Z. W., Weidenspointner, G., and Zoglauer, A.

Subjects
RADIOACTIVE decay, NUCLEAR reactions, GAMMA ray spectrometry, MONTE Carlo method, ASTROPHYSICAL fluid dynamics
Published
2012

228. A QSO in a Cluster at z=2.4

Author

Hutchings, J. B., Neff, S. G., Hutchings, J. B., and Neff, S. G.

Abstract

Photometry is presented in R, J, H, K of the z=2.37 QSO 0820+296 and its environment. Colours and magnitudes of most of the objects within 50 arcsec of the QSO suggest they are a group of galaxies at the QSO redshift with a young stellar population., Comment: 8 pages plus 1 table and 4 figures. To appear in the Astronomical Journal. Also available at http://www.hia.nrc.ca/eprints.html

Published
1997
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238. JHK Imaging and Photometry of Low z QSOs and Radio Galaxy

Author

Hutchings, J. B., Neff, S. G., Hutchings, J. B., and Neff, S. G.

Abstract

We describe J,H,K deep imaging of 90 arcmin fields around 4 QSOs and one Radio galaxy at redshifts in the range 0.06 to 0.30, and show their images, luminosity profiles, and NIR 2-colour diagrams of objects. We find that the QSO hosts are all resolved, and compare them with previous CCD images. The host galaxy colours are consistent with old and young stellar populations at the QSO redshift. The colours of nearby galaxies suggest that all the AGN live in groups of generally smaller companion galaxies, mostly with evolved populations at the same redshift. The two radio-loud objects live in richer cluster environments than the others. Gissel population models indicate reddening in the galaxies, star-forming regions, and possibly a systematic H-K offset. The QSO luminosity profiles are complex and reveal some of their tidal disturbance and star-formation history., Comment: 22 pages of text (latex), 2 tables )latex), and 15 figures (postscript). Accepted for publication in AJ, February 1997. Also available at http://www.dao.nrc.ca/DAO/SCIENCE/science.html

Published
1996
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239. Ultraviolet Imagery of NGC 6752: A Test of Extreme Horizontal Branch Models

Author

Landsman, W. B., Sweigart, A. V., Bohlin, R. C., Neff, S. G., O'Connell, R. W., Roberts, M. S., Smith, A. M., STecher, T. P., Landsman, W. B., Sweigart, A. V., Bohlin, R. C., Neff, S. G., O'Connell, R. W., Roberts, M. S., Smith, A. M., and STecher, T. P.

Abstract

We present a 1620 A image of the nearby globular cluster NGC 6752 obtained with the Ultraviolet Imaging Telescope (UIT) during the Astro-2 mission of the Space Shuttle Endeavour in 1995 March. An ultraviolet-visible color-magnitude diagram (CMD) is derived for 216 stars matched with the visible photometry of Buonanno et al. (1986). This CMD provides a nearly complete census of the hot horizontal branch (HB) population with good temperature and luminosity discrimination for comparison with theoretical tracks. The observed data show good agreement with the theoretical zero-age horizontal branch (ZAHB) of Sweigart (1996) for an assumed reddening of E(B-V) = 0.05 and a distance modulus of 13.05. The observed HB luminosity width is in excellent agreement with the theoretical models and supports the single star scenario for the origin of extreme horizontal branch (EHB) stars. However, only four stars can be identified as post-EHB stars, whereas almost three times this many are expected from the HB number counts. If this effect is not a statistical anomaly, then some non-canonical effect may be decreasing the post-EHB lifetime. The recent non-canonical models of Sweigart (1996), which have helium-enriched envelopes due to mixing along the red giant branch, cannot explain the deficit of post-EHB stars, but might be better able to explain their luminosity distribution., Comment: 14 pages, AASTeX, includes 4 EPS figures ApJ Letters accepted

Published
1996
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240. Ultraviolet Imaging Observations of the cD Galaxy in Abell 1795: Further Evidence for Massive Star Formation in a Cooling Flow

Author

Smith, Eric P., Bohlin, R. C., Bothun, G. D., O'Connell, R. W., Roberts, M. S., Neff, S. G., Smith, A. M., Stecher, T. P., Smith, Eric P., Bohlin, R. C., Bothun, G. D., O'Connell, R. W., Roberts, M. S., Neff, S. G., Smith, A. M., and Stecher, T. P.

Abstract

We present images from the Ultraviolet Imaging Telescope of the Abell 1795 cluster of galaxies. We compare the cD galaxy morphology and photometry of these data with those from existing archival and published data. The addition of a far--UV color helps us to construct and test star formation model scenarios for the sources of UV emission. Models of star formation with rates in the range $\sim5-20M_{\sun}$yr$^{-1}$ indicate that the best fitting models are those with continuous star formation or a recent ($\sim4$ Myr old) burst superimposed on an old population. The presence of dust in the galaxy, dramatically revealed by HST images complicates the interpretation of UV data. However, we find that the broad--band UV/optical colors of this cD galaxy can be reasonably matched by models using a Galactic form for the extinction law with $E_{B-V}=0.14$. We also briefly discuss other objects in the large UIT field of view., Comment: To appear in the Astrophysical Journal. 14 AAS preprint style pages plus 7 figures

Published
1996
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241. Ultraviolet Imaging Telescope Observations of OB Stars in the N 11 Region of the LMC

Author

Parker, J. Wm., Hill, J. K., Bohlin, R. C., O'Connell, R. W., Neff, S. G., Roberts, M. S., Smith, A. M., Stecher, T. P., Parker, J. Wm., Hill, J. K., Bohlin, R. C., O'Connell, R. W., Neff, S. G., Roberts, M. S., Smith, A. M., and Stecher, T. P.

Abstract

We present an analysis of far-ultraviolet (FUV: 130-180 nm) and optical (U, B, and V) data of the stellar and nebular content of the OB associations LH 9, 10, and 13 in the Large Magellanic Cloud region N 11. The FUV images from The Ultraviolet Imaging Telescope strongly select the hot O and B stars; over 1900 stars were detected in the FUV to a limiting magnitude of m(FUV) = 17 mag. The resulting FUV photometry combined with optical ground-based data indicate there are approximately 88 confirmed or candidate O stars in the LH 9, 10, and 13 fields alone (in an area of ~ 41 arcmin$^2$), and possibly as many as 170 to 240 O-type stars within the entire 40~arcmin-diameter field of view., Comment: AAS LaTeX style, 6 pages, 5 figures (Fig 1 as a GIF file, Figs 2-5 as encapsulated PostScript for embedding in the LaTeX file). Complete gzipped PostScript paper (including Figure 1) can be obtained from: http://k2.space.swri.edu/papers/papers.html In press in The Astrophysical Journal Letters

Published
1996
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242. UV Colors and Extinctions of HII Regions in the Whirlpool Galaxy (M51)

Author

Hill, J. K., Waller, W. H., Cornett, R. H., Bohlin, R. C., Cheng, K. -P., Neff, S. G., O'Connell, R. W., Roberts, M. S., Smith, A. M., Hintzen, P. M. N., Smith, E. P., Stecher, T. P., Hill, J. K., Waller, W. H., Cornett, R. H., Bohlin, R. C., Cheng, K. -P., Neff, S. G., O'Connell, R. W., Roberts, M. S., Smith, A. M., Hintzen, P. M. N., Smith, E. P., and Stecher, T. P.

Abstract

Far-UV (1520 ang.), U, H-alpha, and R images of the interacting Sbc spiral galaxy M51 were obtained by the Ultraviolet Imaging Telescope (UIT) and at Mt. Laguna Observatory. The mu(152)-mu(U) radial gradient of >1 mag, becoming bluer with increasing radius, is attributed primarily to a corresponding radial extinction gradient. Magnitudes in both UV bands and H-alpha fluxes are reported for 28 HII regions. Optical extinctions for the 28 corresponding UV sources are computed from the measured m(152)-U colors by fitting to the optical extinctions of Nakai and Kuno (1995). The normalized far-UV extinction A(152)/E(B-V) increases with radius or decreasing metallicity, from 5.99 to 6.54, compared with the Galactic value 8.33. The best-fit m(152)-U color for no extinction, -3.07, is the color of a model solar metallicity starburst of age ~2.5 Myr with IMF slope -1.0. HII regions show decreasing observed H-alpha fluxes with decreasing radius, relative to the H-alpha fluxes predicted from the observed f(152) for age 2.5 Myr, after correction for extinction. We attribute the increasing fraction of ``missing'' H-alpha flux with decreasing radius to increasing extinction in the Lyman continuum. Increasing extinction-corrected far-UV flux of the HII regions with decreasing radius is probably a result of the corresponding increasing column density of the interstellar gas resulting in larger mass OB associations. The estimated dust-absorbed Lyman continuum flux is ~0.6 times the far-infrared energy flux of M51 observed by IRAS., Comment: 21 pages, 6 figures, latex, uses AASMS4 and EPSF

Published
1996
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245. An update on the Axion Helioscopes front: current activities at CAST and the IAXO project

Author

Dafni, T., Arik, M., Armengaud, E., Aune, S., Avignone, F.T., Barth, K., Belov, A., Betz, M., Bräuninger, H., Brax, P., Breijnholt, N., Brun, P., Cantatore, G., Carmona, J.M., Carosi, G.P., Caspers, F., Caspi, S., Cetin, S.A., Chelouche, D., Christensen, F.E., Collar, J.I., Dael, A., Davenport, M., Derbin, A.V., Desch, K., Diago, A., Döbrich, B., Dratchnev, I., Dudarev, A., Eleftheriadis, C., Fanourakis, G., Ferrer-Ribas, E., Friedrich, P., Galán, J., García, J.A., Gardikiotis, A., Garza, J.G., Gazis, E.N., Georgiopoulou, E., Geralis, T., Gimeno, B., Giomataris, I., Gninenko, S., Gómez, H., González-Díaz, D., Gruber, E., Guendelman, E., Guthörl, T., Hailey, C.J., Hartmann, R., Hauf, S., Haug, F., Hasinoff, M.D., Hiramatsu, T., Hoffmann, D.H.H., Horns, D., Iguaz, F.J., Irastorza, I.G., Isern, J., Imai, K., Jacoby, J., Jaeckel, J., Jakobsen, A.C., Jakovčić, K., Kaminski, J., Kawasaki, M., Karuza, M., Königsmann, K., Kotthaus, R., Krčmar, M., Kousouris, K., Krieger, C., Kuster, M., Lakić, B., Laurent, J.M., Limousin, O., Lindner, A., Liolios, A., Ljubičić, A., Luzón, G., Matsuki, S., Muratova, V.N., Neff, S., Niinikoski, T., Nones, C., Ortega, I., Papaevangelou, T., Pivovaroff, M.J., Raffelt, G., Redondo, J., Riege, H., Ringwald, A., Rodríguez, A., Rosu, M., Russenschuck, S., Ruz, J., Saikawa, K., Savvidis, I., Sekiguchi, T., Semertzidis, Y.K., Shilon, I., Sikivie, P., Silva, H., Solanki, S.K., Stewart, L., ten Kate, H.H.J., Tomas, A., Troitsky, S., Vafeiadis, T., van Bibber, K., Vedrine, P., Villar, J.A., Vogel, J.K., Walckiers, L., Weltman, A., Wester, W., Yildiz, S.C., and Zioutas, K.

Abstract

Although they have not yet been detected, axions and axion-like particles (ALPs) continue to maintain the interest (even increasingly so) of the rare-event searches community as viable candidates for the Dark Matter of the Universe but also as a solution for several other puzzles of astrophysics. Their property of coupling to photons has inspired different experimental methods for their detection, one of which is the helioscope technique. The CERN Axion Solar Telescope (CAST) is the most sensitive helioscope built up to date and has recently published part of the latest data taken with the magnet bores gradually filled with 3He, probing the mass range up to 1.17 eV. The International AXion Observatory (IAXO) is being proposed as a facility where different axion studies can be performed, with the primary goal to study axions coming from the Sun. Designed to maximize sensitivity, it will improve the levels reached by CAST by almost 5 orders of magnitude in signal detection, that is more than one order of magnitude in terms of gaγ. Here we will summarize the most important aspects of the helioscopes, and focus mainly on IAXO, based on the recent papers [1, 2].

Published
2016
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250. Far-ultraviolet Color Gradients in Early-Type Galaxies

Author

Ohl, R. G., primary, O'Connell, R. W., additional, Bohlin, R. C., additional, Collins, N. R., additional, Dorman, B., additional, Fanelli, M. N., additional, Neff, S. G., additional, Roberts, M. S., additional, Smith, A. M., additional, and Stecher, T. P., additional

Published
1998
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