Search Publications
Magnetic Helicity Exchange Between Neighboring Active Regions
Zhang, H.; Yang, S.; Büchner, J.
Addressing the long-lasting problem of the magnetic helicity distribution in the solar corona, a proof for magnetic helicity exchange between two neighboring emerging active regions (ARs) was found: when AR 9188 emerged, it first started to accumulate positive helicity, while the later neighboring emerging AR 9192 accumulated negative helicity. At…
A New Way to Infer Variations of the Seismic Solar Radius
Hill, F.; González Hernández, I.; Scherrer, P.
We show that the mean phase of waves propagating all the way from the far side of the Sun to the front side, as measured by seismic holography, varies with time. The change is highly anticorrelated with solar cycle activity and is consistent with other recent results on the variation of the seismic radius of the Sun. The phase change that we obser…
Chandra Observation of Quiescent Low-Mass X-Ray Binaries in the Globular Cluster NGC 6304
Pavlov, George G.; Guillot, Sebastien; Zavlin, Vyacheslav E. +2 more
This paper presents the analysis of candidate low-mass X-ray binaries in quiescence (qLMXBs) observed during a short Chandra/ACIS observation of the globular cluster (GC) NGC 6304. Two out of the three candidate qLMXBs of this cluster, XMMU 171433-292747 and XMMU 171421-292917, lie within the field of view. This permits comparison with the discove…
X-ray Emission from the Base of a Current Sheet in the Wake of a Coronal Mass Ejection
Krucker, S.; Lin, R. P.; Saint-Hilaire, P.
Following a coronal mass ejection (CME) which started on 2002 November 26, RHESSI observed for 12 hr an X-ray source above the solar limb, at altitudes between 0.1 and 0.3 RS above the photosphere. The Geostationary Operational Environmental Satellite baseline was remarkably high throughout this event. The X-ray source's temperature pea…
A Hubble Space Telescope View of the Interstellar Environments of Young Stellar Objects in the Large Magellanic Cloud
Chu, You-Hua; Gruendl, Robert A.; Looney, Leslie W. +2 more
We have used archival Hubble Space Telecope (HST) Hα images to study the immediate environments of massive and intermediate-mass young stellar object (YSO) candidates in the Large Magellanic Cloud (LMC). The sample of YSO candidates, taken from Gruendl & Chu, was selected based on Spitzer IRAC and MIPS observations of the entire LMC and comple…
No Neutron Star Companion to the Lowest Mass SDSS White Dwarf
Anderson, Scott F.; Heinke, Craig; Kilic, Mukremin +6 more
SDSS J091709.55+463821.8 (hereafter J0917+4638) is the lowest surface gravity white dwarf (WD) currently known, with log g = 5.55 ± 0.05 (M ≈ 0.17 M sun). Such low-mass white dwarfs (LMWDs) are believed to originate in binaries that evolve into WD/WD or WD/neutron star (NS) systems. An optical search for J0917+4638's companion showed th…
X-ray Diagnostics of Thermal Conditions of the Hot Plasmas in the Centaurus Cluster
Fukazawa, Y.; Tamura, T.; Matsushita, K. +9 more
X-ray data of the Centaurus cluster, obtained with XMM-Newton for 45 ks, were analyzed. Deprojected EPIC spectra from concentric thin-shell regions were reproduced equally well by a single-phase plasma emission model, or by a two-phase model developed by ASCA, both incorporating cool (1.7-2.0 keV) and hot (~ 4 keV) plasma temperatures. However, EP…
Rest-Frame UV Versus Optical Morphologies of Galaxies Using Sérsic Profile Fitting: The Importance of Morphological K-Correction
Wadadekar, Yogesh; Rawat, Abhishek; De Mello, Duilia
We show a comparison of the rest-frame UV morphologies of a sample of 162 intermediate-redshift (z median = 1.02) galaxies with their rest-frame optical morphologies. We select our sample from the deepest near-UV image obtained with the Hubble Space Telescope (HST) using the Wide Field Planetary Camera 2 (WFPC2; F300W) as part of the pa…
Super Star Clusters in SBS0335-052E
Schneider, Glenn; Kennicutt, Robert C.; Vanzi, Leonardo +3 more
As one of the lowest metallicity star-forming galaxies, with a nucleus of several super star clusters (SSCs), SBS0335-052E is the subject of substantial current study. We present new insights on this galaxy based on new and archival high spatial resolution NICMOS and attitude control system images. We provide new measurements and limits on the siz…
New X-Ray Observations of the Old Nova CP Puppis and of the More Recent Nova V351 Puppis
Mukai, K.; de Martino, D.; Orio, M. +2 more
We present X-ray observations of the field containing Nova Puppis 1942 (CP Pup) and Nova Puppis 1991 (V351 Pup), done with ASCA in 1998, and with XMM-Newton in 2005. The X-ray and UV luminosity of CP Pup seem to have remained approximately constant since the last X-ray observations of the 1980s, while the optical luminosity has decreased. The X-ra…