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WFPC2 Observations of the Double Cluster NGC 1850 in the Large Magellanic Cloud

Panagia, N.; Ewald, S. P.; Romaniello, M. +2 more

HST-WFPC2 optical and ultraviolet imaging observations of the young double cluster NGC 1850 in the LMC are presented. The main cluster, NGC 1850A, is a globular-like cluster and has an age of 50+/-10 Myr, while the subcluster, NGC 1850B, which is more loosely distributed, is very young at 4.3 +/- 0.9 Myr. Its young age is confirmed by the detectio…

Hubble Space Telescope Goddard High-Resolution Spectrograph H 2 Rotational Spectra of Jupiter's Aurora

Vidal-Madjar, Alfred; Clarke, John T.; Ben Jaffel, Lotfi +6 more

We have observed the emission spectrum from Jupiter's north auroral atmosphere with 0.57 A spectral resolution over 1204-1241 A. Bright emissions have been detected from 50 deg to 60 deg latitude at locations consistent with 6 to 30 R _J auroral ovals, with much fainter emissions away form the auroral ovals. The emission spectrum is well…

Multiwavelength Observations of Hercules X-1/HZ Herculis

Mihara, T.; Kahabka, P.; Charles, P. A. +16 more

We present first results from a multiwavelength campaign to observe the binary pulsar system Her X-1/ HZ Her. The campaign spanned 4 days during 1993 August: observations were taken with five satellites (IUE, EUVE, ROSAT, ASCA, and CGRO/BATSE) and several ground-based facilities. A substantial, unexpected drop in flux at X-ray energies, with no ch…

Supersoft X-Ray Sources.

Hasinger, G.

The Theta -z Relation for HST Bulges and Disks out to Z 0.8

Casertano, Stefano; Glazebrook, Karl; Green, Richard F. +9 more

We present HST scale lengths and ground-based redshifts for 63 faint field galaxies down to I <~ 21.5 mag from the Medium-Deep Survey. These have measured redshifts z <~ 0.8 and half-light radii 0.1" < r_e_, r_s_ < 5". We present the {THETA}-z relation for r^1/4^-bulges and exponential disks separately for world models with q_0_ = 0.0-…

No fundamental-mode pulsation in R Leonis ?

Tuthill, P. G.; Feast, M. W.; Haniff, C. A. +1 more

We present new and precise angular diameter measurements of the long-period variable R Leonis at 833 and 903 nm. Our inferred photospheric diameter (38±2.5 mas) and stellar effective temperature (2459 + 150 K) are both in good agreement with recent determinations made at the same variability phase in the near-infrared. Assuming a parallax of 8.3 m…

Hubble Space Telescope Planetary Camera Observations of ARP 220

Faber, S. M.; Currie, Douglas G.; Groth, Edward J. +2 more

Planetary Camera images of peculiar galaxy Arp 220 taken with V, R, and I band filters reveal a very luminous object near the position of the western radio continuum source, assumed to be the major nucleus, and seven lesser objects within 2" of this position. The most luminous object is formally coincident with the radio source to within the error…

Magnetic reconnection ahead of a coronal mass ejection

McComas, D. J.; Forsyth, R. J.; Phillips, J. L. +3 more

On 29 November 1990 the Ulysses spacecraft passed through a series of interplanetary structures which suggest that reconnection had occurred on open field lines ahead of a coronal mass ejection (CME), changing the magnetic topology of the upstream region. We observe in sequence 1) a heat flux dropout, 2) a region of counterstreaming halo electrons…

Deep HST Imaging of Distant Weak Radio and Field Galaxies

Dunlop, J. S.; Keel, W. C.; Windhorst, R. A. +4 more

We present deep Hubble Space Telescope (HST) Wide-Field Camera V- and I-band images of three distant weak radio galaxies with z = 0.311-2.390 and seven field galaxies with z = 0.131-0.58. The images were deconvolved with both the Lucy and multiresolution CLEAN methods, which yield a restoring FWHM of <= 0.2", (nearly) preserve photons and signa…

Ulysses near-ecliptic observations of differential flow between protons and alphas in the solar wind

Goldstein, B. E.; Bame, S. J.; Neugebauer, M. +1 more

The evolution of differential streaming between protons and alpha particles in the solar wind was observed with the solar wind plasma experiment on the Ulysses spacecraft over the solar range of 1.15 to 5.40 AU between November 18, 1990, and May 5, 1992. The correlation of the difference in ion speeds, ΔV=||V_α||-||V_p||, with …