Science Archives Publication System

On the history of star formation in the bar of the Large Magellanic Cloud.

Bibcode: 1997A&A...322L..13A

Gustafsson, B.; Ardeberg, A.; Linde, P. +1 more

With the HST PC and uvby photometry, we investigate evolutionary signatures in a field in the centre of the LMC Bar. Field stars close to the turn off point in the HR diagram are used for a study of ages and evolution of the stellar populations dominating the Bar as well as for determination of the abundance of heavy elements. Including fainter st…

1997 • Astronomy and Astrophysics

eHST 25

Origins of the first-order anisotropy of ∼ 1 MeV protons in the Jovian magnetosphere during the Ulysses flyby: flux gradients and plasma flows

DOI: 10.1016/S0032-0633(97)00010-X Bibcode: 1997P&SS...45.1143L

Balogh, A.; Forsyth, R. J.; Dunlop, M. W. +4 more

For zeroth-order distributions of energetic ions which are not too far from isotropy, the field-perpendicular first-order anisotropy results principally from the E × B plasma flow transverse to the magnetic field, and from spatial gradients in the ion flux. A technique is presented which separates these sources of anisotropy by examining their dep…

1997 • Planetary and Space Science

Ulysses 24

UIT: Ultraviolet Observations of the Small Magellanic Cloud

DOI: 10.1086/118317 Bibcode: 1997AJ....113.1011C

Parker, Joel Wm.; O'Connell, R. W.; Bohlin, R. C. +9 more

A mosaic of four UIT far-UV (FUV) (lambda_ {eff} = 1620 Angstroms) images, with derived stellar and HII region photometry, is presented for most of the Bar of the SMC. The UV morphology of the SMC's Bar shows that recent star formation there has left striking features including: a) four concentrations of UV-bright stars spread from northeast to so…

1997 • The Astronomical Journal

IUE 24

Bow shock analysis at comets Halley and Grigg-Skjellerup

DOI: 10.1029/96JA04002 Bibcode: 1997JGR...102.7105C

Coates, A. J.; Neubauer, F. M.; Mazelle, C.

The interaction of an active comet with the solar wind is effected by the pickup of heavy cometary ions over extended regions of space. It was predicted before any spacecraft encounters with comets that a bow shock would form at a critical point in the mass-loaded flow. Here we present an analysis of the results from Giotto's encounters of comets …

1997 • Journal of Geophysical Research

Giotto 24

Laboratory Identification of Temperature Diagnostic Si VII and S IX Lines Present in the Solar Coronal Spectra Measured by SUMER/SOHO

DOI: 10.1086/304652 Bibcode: 1997ApJ...487..956K

Schühle, U.; Feldman, U.; Laming, J. M. +3 more

The solar coronal spectrum between 500 and 1610 Å and at a height of 21,000 km above the west equatorial limb has recently been recorded by the SUMER instrument on SOHO. Using laboratory spectra obtained with the beam-foil technique, we report the identification of 32 lines observed in this spectrum as 2s²2p³3s-2s²…

1997 • The Astrophysical Journal

SOHO 24

Spectrophotometric Data of the Central Star of the Large Magellanic Cloud Planetary Nebula N66: Quantitative Analysis of Its WN-Type Spectrum

DOI: 10.1086/304943 Bibcode: 1997ApJ...491..233P

Hamann, W. -R.; Koesterke, L.; Torres-Peimbert, S. +5 more

Hubble Space Telescope, IUE, and ground-based observations of the central star of the LMC planetary nebula N66 (CS N66), obtained in different epochs, are presented. Since 1990, CS N66 has displayed remarkable short- and long-term spectroscopic and photometric changes amounting to more than 3 mag in the optical. Expanding model atmospheres have be…

1997 • The Astrophysical Journal

IUE eHST 24

HST Images of the High-Excitation Herbig-Haro Object HH 32

DOI: 10.1086/118682 Bibcode: 1997AJ....114.2736C

Noriega-Crespo, A.; Raymond, J.; Curiel, S. +2 more

We present high angular resolution emission-line and continuum images of the remarkable Herbig-Haro jet HH 32 obtained with the Wide Field and Planetary Camera 2 (WFPC2) aboard the Hubble Space Telescope. We have obtained narrow band [S ii] λλ6716,673l, [N ii] 6583 and Hα images, as well as an R continuum image, of this HH jet. The 0."l spatial re…

1997 • The Astronomical Journal

eHST 24

Ultraviolet Imaging of the Globular Cluster 47 Tucanae

DOI: 10.1086/118619 Bibcode: 1997AJ....114.1982O

O'Connell, Robert W.; Bohlin, Ralph C.; Landsman, Wayne B. +8 more

We have used the Ultraviolet Imaging Telescope to obtain far-UV (1620 Å), wide field (40' diameter) images of the prototypical metal-rich globular cluster 47 Tucanae. We find a population of about 20 hot (T_eff>9000 K) objects near or above the predicted UV luminosity of the hot horizontal branch (HB) and lying within two half-light r…

1997 • The Astronomical Journal

IUE eHST 24

Spatially Resolved Spectra of V1974 Cygni (Nova Cygni 1992) with the Goddard High Resolution Spectrograph

DOI: 10.1086/304850 Bibcode: 1997ApJ...490..393S

Shore, Steven N.; Hauschildt, Peter H.; Starrfield, Sumner +1 more

We report the observation of spatially resolved low-resolution GHRS spectra of the shell of the bright Galactic ONeMg nova Cygni 1992. The spectra were obtained in 1995 September, after the X-ray turnoff of the nova. We have determined the dynamical structure of the ejecta and show the evolution of the ionization within the ejecta. Abundance limit…

1997 • The Astrophysical Journal

IUE eHST 24

The High-Redshift Radio Galaxy MRC 0406-244

DOI: 10.1086/304307 Bibcode: 1997ApJ...484..163R

McCarthy, Patrick J.; Persson, S. E.; Athreya, Ramana M. +1 more

We present HST and ground-based multiwavelength observations of the distant radio galaxy MRC 0406-244. Ground-based visible and near-IR images reveal two distinct components that are aligned with the radio source axis. One of these has the red optical-to-IR and blue UV colors characteristic of radio galaxies, while the other is red in all colors. …

1997 • The Astrophysical Journal

eHST 23