Search Publications
High-resolution Studies of the Polar Magnetic Fields during Cycle 23
Turner, J.; Varsik, J.; Durrant, C. J. +1 more
High-resolution mosaics of the solar polar magnetic fields have been constructed using individual magnetograms obtained with the video magnetograph of the Big Bear Solar Observatory, and the properties of these mosaics are demonstrated in this paper. The mosaics show selected regions of the polar fields on several days during the rising phase of C…
Analysis of HST Ultraviolet Spectra for T Tauri Stars: Estimating the Interstellar Extinction and the Contribution from an Accretion Shock to the Emission-Continuum Formation
Lamzin, S. A.; Kravtsova, A. S.
Limb Prominence Eruption on 11 August 2000 as Seen From Ground- and Space-Based Observations
Abramenko, V. I.; Yurchyshyn, V. B.; Shakhovskaya, A. N.
We report on a prominence eruption as seen in Hα with the Crimean Lyot coronagraph, the global Hα network, and coronal images from the LASCO C2 instrument on board SOHO. We observed an Hα eruption at the northwest solar limb between 07:38:50 UT and 07:58:29 UT on 11 August 2000. The eruption originated in a quiet-Sun region and was not associated …
The Beginning of the End: Hubble Space Telescope Images of Seyfert's Sextet
Charlton, Jane C.; Gallagher, Sarah C.; English, Jayanne +4 more
Hubble Space Telescope (HST) Wide Field Planetary Camera 2 images of Hickson Compact Group (HCG) 79, Seyfert's Sextet, are presented. Both point sources and extended sources detected on the three wide-field chips were photometered in four filters: F336W, F439W, F555W, and F814W. Unlike other HCGs that have been imaged with HST, there do not appear…
Observation of decay phases of solar energetic particle events at 1 and 5 AU from the Sun
Balogh, A.; Dalla, S.; Heber, B. +2 more
The slow decay phase of gradual solar energetic particle (SEP) events has been interpreted as an indication of particle reservoirs being established in the inner heliosphere. The same phenomenon is sometimes termed spectral invariance and explained in terms of a magnetic bottle effect, whereby a barrier impedes particle escape. In alternative to t…
Detection of new optical counterpart candidates to PSR B1951+32 with HST/WFPC2
Golden, A.; Shearer, A.; Butler, R. F.
There remain several definitive gamma -ray pulsars that are as yet undetected in the optical regime. A classic case is the pulsar PSR B1951+32, associated with the complex CTB 80 SNR. Previous ground based high speed 2-d optical studies have ruled out candidates to mV ~ 24. Hester (2000a) has reported an analysis of archival HST/WFPC2 o…
On the Absolute Calibration of the Cepheid Distance Scale Using Hipparcos Parallaxes
Di Benedetto, G. P.
The fundamental Hipparcos parallaxes (HIPP) of 219 Cepheids are used for the absolute calibration of the Galactic distance scale sampled by a modern Baade-Wesselink (BW) distance indicator, which reliably accounts for pulsation and thermal properties of Cepheid variable stars. Notably we map thermal properties into the Johnson-Cousins color (V-I).…
Solar particle events with helium-over-hydrogen enhancement in the energy range up to 100 MeV nucl−1
Plunkett, S. P.; Thompson, B. J.; Torsti, J. +5 more
Flux measurements of solar energetic particles (SEPs) in the ERNE instrument onboard SOHO indicate that the abundance of 4He-nuclei compared to protons in the energy range up to 100 MeV nucl−1 was exceptionally high during the particle events on 27 May 1998 and 28 December 1999. The 4He/p ratio stayed between 0.15-…
Touring the Saturnian System
Wolf, Aron A.
The Cassini mission to Saturn employs a Saturn orbiter and a Titan probe to conduct an intensive investigation of the Saturnian system. The orbiter flies a series of orbits, incorporating flybys of the Saturnian satellites, called the ‘satellite tour.’ During the tour, the gravitational fields of the satellites (mainly Titan) are used to modify an…
Variation of Acoustic Power with Magnetic Field as Seen in Gong+ Data
Venkatakrishnan, P.; Kumar, Brajesh; Tripathy, S. C.
The acoustic spectra in sunspots are known to be richer in higher frequency power. We have attempted a generalized study of the effect of magnetic fields on the shape of the acoustic spectrum using GONG+ bread-board data (spatial scale of ∼ 2 arc sec per pixel) of 11 May 2000 and 12 June 2000. The mean power spectra of the velocity oscillations we…