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The Narrow-Line Regions of LINERS as Resolved with the Hubble Space Telescope
Ho, Luis C.; Maoz, Dan; Eracleous, Michael +1 more
Low-ionization nuclear emission-line regions (LINERs) exist in the nuclei of a large fraction of luminous galaxies, but their connection with the active galactic nucleus (AGN) phenomenon has remained elusive. We present Hubble Space Telescope (HST) narrowband ([O III] λ5007 and Hα+[N II]) emission-line images of the central regions of 14 galaxies …
Turbulent Solar Convection and Its Coupling with Rotation: The Effect of Prandtl Number and Thermal Boundary Conditions on the Resulting Differential Rotation
Toomre, J.; Elliott, J. R.; Miesch, M. S.
The dynamics of the vigorous convection in the outer envelope of the Sun must determine the transport of energy, angular momentum, and magnetic fields and must therefore be responsible for the observed surface activity and the angular velocity profile inferred helioseismically from SOI-MDI p-mode frequency splittings. Many different theoretical tr…
The Contribution of Field OB Stars to the Ionization of the Diffuse Ionized Gas in M33
Hoopes, Charles G.; Walterbos, René A. M.
We present a study of the ionizing stars associated with the diffuse ionized gas (DIG) and H II regions in the nearby spiral galaxy M33. We compare our Schmidt Hα image to the far-ultraviolet (FUV, 1520 Å) image from the Ultraviolet Imaging Telescope (UIT). The Hα/FUV ratio is higher in H II regions than in the DIG, suggesting an older population …
The Formation of Encke Meteoroids and Dust Trail
Reach, William T.; Sykes, Mark V.; Lien, David +1 more
We observed Comet 2P/Encke with the Infrared Space Observatory ISOCAM on July 14, 1997, from a particularly favorable viewing geometry above the comet's orbital plane and at a distance of 0.25 AU. A structured coma was observed, along with a long, straight dust trail. For the first time, we are able to observe the path of particles as they evolve …
Absolute proper motions of open clusters. I. Observational data
Wielen, R.; Dettbarn, C.; Baumgardt, H.
Mean proper motions and parallaxes of 205 open clusters were determined from their member stars found in the Hipparcos Catalogue. 360 clusters were searched for possible members, excluding nearby clusters with distances D < 200 pc. Members were selected using ground based information (photometry, radial velocity, proper motion, distance from th…
The Unusual Infrared Object HDF-N J123656.3+621322
Papovich, Casey; Dickinson, Mark; Ferguson, Henry C. +11 more
We describe an object in the Hubble Deep Field North with very unusual near-infrared properties. It is readily visible in Hubble Space Telescope NICMOS images at 1.6 µm and from the ground at 2.2 µm, but it is undetected (with S/N<~2) in very deep WFPC2 and NICMOS data from 0.3 to 1.1 µm. The fν flux density drops b…
Kinematics of young stars. I. Local irregularities
Figueras, F.; Torra, J.; Fernández, D.
The local velocity field of young stars is dominated by the galactic rotation, the kinematics of the Gould Belt and the nearest OB associations and open clusters, and the kinematics of the spiral structure. We re-examined here this local velocity field by using a large sample of nearby O and B stars from the Hipparcos Catalogue. The high quality a…
On the Globular Cluster Initial Mass Function below 1 Msolar
Paresce, Francesco; De Marchi, Guido
Accurate luminosity functions (LFs) for a dozen globular clusters have now been measured at or just beyond their half-light radius using HST. They span almost the entire cluster main sequence (MS) below 0.75 Msolar. All these clusters exhibit LFs that rise continuously from an absolute I magnitude MI~=6 to a peak at MI
ISO-SWS observations of interstellar solid 13CO2: heated ice and the Galactic 12C/13C abundance ratio
de Graauw, Th.; Prusti, T.; van Dishoeck, E. F. +7 more
We present observations of the stretching mode of 13CO_2 ice along 13 lines of sight in the Galaxy, using the Short Wavelength Spectrometer on board of the Infrared Space Observatory (ISO-SWS). Remarkable variations are seen in the absorption band profile in the different lines of sight. The main feature is attributed to 13CO…
Creating Spectral Templates from Multicolor Redshift Surveys
Dickinson, Mark; Budavári, Tamás; Csabai, István +2 more
Understanding how the physical properties of galaxies (e.g., their spectral type or age) evolve as a function of redshift relies on having an accurate representation of galaxy spectral energy distributions. While it has been known for some time that galaxy spectra can be reconstructed from a handful of orthogonal basis templates, the underlying ba…