Search Publications
Classical novae in outburst: The early evolution of the ultraviolet continuum
Altamore, A.; González-Riestra, R.; Cassatella, A.
In the framework of a phenomenological study of the ultraviolet properties of classical novae in outburst, we have selected 12 objects among the best monitored at low resolution with the IUE satellite, and studied the temporal evolution of the ultraviolet continuum and of the O I 1300 Å line flux during the early post-outburst phase. We confirm th…
Hubble Space Telescope Observations of the Cometary Blue Compact Dwarf Galaxy UGC 4483: A Relatively Young Galaxy?
Thuan, Trinh X.; Izotov, Yuri I.
We present V and I photometry of the resolved stars in the cometary blue compact dwarf galaxy UGC 4483 using Hubble Space Telescope Wide Field Planetary Camera 2 images. The resulting I versus V-I color-magnitude diagram (CMD) reaches limiting magnitudes V=27.5 mag and I=26.5 mag for photometric errors less than 0.2 mag. It reveals not only a youn…
Inversion of the Internal Solar Rotation Rate
Eff-Darwich, A.; Korzennik, S. G.; Jiménez-Reyes, S. J.
Accurate determination of the rotation rate in the inner radiative zone (0.2<r/Rsolar<0.5) of the Sun from helioseismic observations requires rotational frequency splittings of exceptional quality. Indeed, only the very low degree modes are sensitive to the dynamics of the deep interior. Low- and intermediate-degree splittings hav…
The Local Interstellar Ultraviolet Radiation Field
Henry, Richard Conn
I have used the Hipparcos Input Catalogue, together with Kurucz model stellar atmospheres and information on the strength of the interstellar extinction, to create a model of the expected intensity and spectral distribution of the local interstellar ultraviolet radiation field, under various assumptions concerning the albedo a of the interstellar …
Gemini Multi-Object Spectrograph Observations of SCUBA Galaxies behind A851
Ivison, R. J.; Smail, Ian; Morrison, G. E. +3 more
We have identified counterparts to two submillimeter (submm) sources, SMM J09429+4659 and SMM J09431+4700, seen through the core of the z=0.41 cluster A851. We employ deep 1.4 GHz observations and the far-infrared/radio correlation to refine the submm positions and then optical and near-infrared imaging to locate their counterparts. We identify an…
The Dwarf Irregular/Wolf-Rayet Galaxy NGC 4214. I. A New Distance, Stellar Content, and Global Parameters
Greggio, Laura; Hopp, Ulrich; Schulte-Ladbeck, Regina E. +2 more
We present the results of a detailed optical and near-IR study of the nearby star-forming dwarf galaxy NGC 4214. We discuss the stellar content, drawing particular attention to the intermediate-age and/or old field stars, which are used as a distance indicator. On images obtained with the Hubble Space Telescope Wide Field Planetary Camera 2 and Ne…
Neon Abundances in the H II Regions of M33
Willner, S. P.; Nelson-Patel, K.
We present neon abundances for 25 H II regions of M33, measured from line profiles of the mid-infrared transitions of [Ne II] and [Ne III] taken with the Infrared Space Observatory Short-Wavelength Spectrometer. The distribution of neon abundances as a function of galactocentric radius is best described as a step, -0.15 dex relative to the solar n…
Cluster observations of the heliospheric current sheet and an associated magnetic flux rope and comparisons with ACE
Balogh, A.; Eastwood, J. P.; Dunlop, M. W. +1 more
Cluster and ACE magnetic field measurements from the 13 February 2001 are presented. On this day the four Cluster spacecraft made two crossings of the heliospheric current sheet (HCS) while in the solar wind and observed a large-scale rotation of the magnetic field in the magnetosheath. These features were also observed by ACE upstream of the Eart…
Transition region explosive events: Do they have a coronal counterpart?
Doyle, J. G.; Madjarska, M. S.; Teriaca, L.
EUV explosive events are a prominent class of phenomena characterizing the solar transition region. Their correct location in the wider frame-work of the outer solar atmosphere can provide important insight on the nature of the transition region itself and its relationship with the hotter corona and the cooler chromosphere. In this paper we presen…
Embedded Star Formation in the Eagle Nebula
Smith, Bradford A.; Hester, J. Jeff; Thompson, Rodger I.
M16 (=NGC 6611), the Eagle Nebula, is a well-studied region of star formation and the source of a widely recognized Hubble Space Telescope (HST) image. High spatial resolution infrared observations with the Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) on HST reveal the detailed morphology of two embedded star formation regions that …