Search Publications
Missions
Journals
Publication Years
Searching for unknown open clusters in the Tycho-2 catalog
Moitinho, A.; Dias, W. S.; Alessi, B. S.
We present 11 new open cluster candidates found in a systematic search for unknown star clusters using the astrometric and photometric data included in the Tycho 2 catalog. The possible existence of these stellar aggregates is supported by the analysis of proper motions, color-magnitude diagrams, stellar density distributions, and by the visual in…
X-Ray Emission from the Pre-planetary Nebula Henize 3-1475
Frank, Adam; Kastner, Joel H.; Sahai, Raghvendra +2 more
We report the first detection of X-ray emission in a pre-planetary nebula, He 3-1475. Pre-planetary nebulae are rare objects in the short transition stage between the asymptotic giant branch (AGB) and planetary nebula evolutionary phases, and He 3-1475, characterized by a remarkable S-shaped chain of optical knots, is one of the most noteworthy me…
The X-ray eclipse of OY Car resolved with XMM-Newton: X-ray emission from the polar regions of the white dwarf
Wheatley, Peter J.; West, Richard G.
We present the XMM-Newton X-ray eclipse light curve of the dwarf nova OY Car. The eclipse ingress and egress are well resolved for the first time in any dwarf nova placing strong constraints on the size and the location of the X-ray emitting region. We find good fits to a simple linear eclipse model, giving ingress/egress durations of 30 +/- 3 s (…
Relationship between CME velocity and active region magnetic energy
Venkatakrishnan, P.; Ravindra, B.
We find an empirical relationship between the initial speed of Coronal Mass Ejection (CME) and the potential magnetic field energy of the associated active region (AR) that closely resembles the Sedov relation between the speed of a blast wave and the blast energy. We conclude that it is the magnetic energy of an AR that drives the CME. The restru…
Emission and Absorption in the M87 LINER
Filippenko, Alexei V.; Ho, Luis C.; Shields, Joseph C. +2 more
The nucleus of M87 displays a LINER spectrum at optical wavelengths, with a nuclear disk of nebulosity that is resolved by the Hubble Space Telescope (HST). We present new results from optical and ultraviolet spectra of the central ~40 pc as measured by HST. In contrast with previous results for the extended disk, the emission-line spectrum of the…
The soft X-ray characteristics of solar flares, both with and without associated CMEs
Culhane, J. L.; Green, L. M.; Harra, L. K. +2 more
The complex relationship between solar flares and coronal mass ejections is investigated using a comparison of flare parameters for a total of 69 ejective and non-ejective flares. In the case of solar flares which do not show mass ejection there seems to be a clear relationship between the peak intensity and duration, with higher intensity events …
A statistical study of compressional waves in the tail current sheet
Balogh, A.; Zhang, T. L.; Klecker, B. +9 more
A statistical study of the Cluster FGM data is performed on compressional waves for 68 selected 12 min intervals when the spacecraft are in or near the neutral sheet. The data are well distributed in local time between 2100 and 0300 LT. The compressional wave power is strongly dependent on the maximum plasma flow velocity (based on the CIS-CODIF d…
The Ringed Spiral Galaxy NGC 4622. I. Photometry, Kinematics, and the Case for Two Strong Leading Outer Spiral Arms
Byrd, Gene G.; Freeman, Tarsh; Buta, Ronald J.
The intriguing nearly face-on southern ringed spiral galaxy NGC 4622, the first galaxy definitively shown to have leading spiral structure, is revisited in this paper with new images from the Hubble Space Telescope's (HST) WFPC2, together with ground-based optical and near-IR imaging, and a Fabry-Perot Hα velocity field. The data provide new infor…
Infrared Spectroscopy of 15 Radio Galaxies at 2<z<2.6
Motohara, Kentaro; Iwamuro, Fumihide; Maihara, Toshinori +7 more
Near-infrared spectra of 15 high-redshift radio galaxies (HzRGs) located at 2<z<2.6 were obtained by the OH Airglow Suppressor spectrograph mounted on the Subaru telescope. The UV-optical line ratio diagnostic diagrams indicate that half of the observed HzRGs have extended emission-line regions with low metal abundance, photoionized by a fla…
Hubble Space Telescope STIS Spectrum of RW Aurigae A: Evidence for an Ionized Beltlike Structure and Mass Ejection in Timescales of a Few Hours
Gómez de Castro, Ana I.; Verdugo, Eva
Profiles of the UV semiforbidden lines of C III]1908 and Si III]1892 of RW Aur have been obtained with the Hubble Space Telescope (HST) STIS. The C III]1908 profile shows two high-velocity components at v=+/-170 km s-1 and a central one. The Si III]1892 profile is very broad (FWHM = 293 km s