Search Publications
Signature of Stochastic Acceleration and Cooling Processes in an Outburst Phase of the TeV Blazar ON 231
Gupta, Alok C.; Wiita, Paul J.; Kalita, Nibedita +1 more
We present a detailed spectral and temporal study of the intermediate-type blazar ON 231 during the TeV outburst phase in 2008 June with observations performed by Swift and XMM-Newton. The X-ray flux of the source, which was significantly dominated by the soft photons (below 3-4 keV), varies between 27% and 38% on day timescales, while mild variat…
Long-standing Small-scale Reconnection Processes at Saturn Revealed by Cassini
Coates, A. J.; Krupp, N.; Dougherty, M. K. +12 more
The internal mass source from the icy moon Enceladus in Saturn’s rapidly rotating magnetosphere drives electromagnetic dynamics in multiple spatial and temporal scales. The distribution and circulation of the internal plasma and associated energy are thus crucial in understanding Saturn’s magnetospheric environment. Magnetic reconnection is one of…
Chandra Observations of the Massive Star-forming Region Onsala 2
Skinner, Stephen L.; Güdel, Manuel; Sokal, Kimberly R.
Previous radio and infrared observations have revealed an obscured region of high-mass star formation in Cygnus known as Onsala 2 (ON2). Within this region lies the optically revealed young stellar cluster Berkeley 87, which contains several OB stars and the rare oxygen-type Wolf-Rayet star WR 142. Previous radio studies of ON2 have also discovere…
A Sub-damped Lyα Absorber with Unusual Abundances: Evidence of Gas Recycling in a Low-redshift Galaxy Group
Frye, Brenda L.; Bowen, David V.; Tripp, Todd M. +3 more
Using Hubble Space Telescope/Space Telescope Imaging Spectrograph G140M spectroscopy, we investigate an absorption-line system at z = 0.07489 in the spectrum of the quasi-stellar object PG 1543+489 (z QSO = 0.401). The sightline passes within ρ = 66 kpc of an edge-on 2{L}* disk galaxy at a similar redshift, but the galaxy be…
The Enhancement of the Energetic Particle Intensities in ICMEs
Li, Gang; Wang, Yuming; Shen, Chenglong +5 more
The behavior of energetic particles in interplanetary coronal mass ejections (ICMEs) is of great interest. In general, due to the relatively closed magnetic structures of ICMEs, the energetic-particle intensities are usually depressed in them. However, previous studies have found some counterexamples. In this work, using protons with energies form…
Understanding the Plasma and Magnetic Field Evolution of a Filament Using Observations and Nonlinear Force-free Field Modeling
Savcheva, Antonia; van Driel-Gesztelyi, Lidia; Green, Lucie M. +4 more
We present observations and magnetic field models of an intermediate filament present on the Sun in 2012 August, associated with a polarity inversion line that extends from AR 11541 in the east into the quiet Sun at its western end. A combination of Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly, SDO/Helioseismic and Magnetic Imager…
Blue Straggler Stars beyond the Milky Way. IV. Radial Distributions and Dynamical Implications
Sills, Alison; Hong, Jongsuk; Deng, Licai +3 more
Blue straggler stars (BSSs) have been proposed as powerful indicators to measure the dynamical state of Galactic globular clusters (GCs). Here we examine for the first time whether this framework of BSSs as dynamical clocks, which was specifically developed for Galactic GCs, may also hold for younger GCs in the Large Magellanic Cloud (LMC). Using …
The Mass of the White Dwarf Companion in the Self-lensing Binary KOI-3278: Einstein versus Newton
Kruse, Ethan; Latham, David W.; Quinn, Samuel N. +10 more
KOI-3278 is a self-lensing stellar binary consisting of a white dwarf secondary orbiting a Sun-like primary star. Kruse & Agol noticed small periodic brightenings every 88.18 days in the Kepler photometry and interpreted these as the result of microlensing by a white dwarf with about 63% of the mass of the Sun. We obtained two sets of spectra …
A Chandra Study: Are Dwarf Carbon Stars Spun Up and Rejuvenated by Mass Transfer?
Roulston, Benjamin R.; Green, Paul J.; Anderson, Scott F. +9 more
Carbon stars (with C/O > 1) were long assumed to all be giants, because only asymptotic giant branch (AGB) stars dredge up significant carbon into their atmospheres. The case is nearly ironclad now that the formerly mysterious dwarf carbon (dC) stars are actually far more common than C giants and have accreted carbon-rich material from a former…
Are the Double-mode Bulge RR Lyrae Stars with Identical Period Ratios the Relic of a Disrupted Stellar System?
Rich, R. Michael; Kunder, Andrea; Johnson, Christian I. +6 more
Radial velocities of 15 double-mode bulge RR Lyrae (RR01) stars are presented, 6 of which belong to a compact group of RR01 stars in pulsation space, with the ratio of first-overtone period to fundamental mode period, P fo /P f ∼ 0.74, and P f ∼ 0.44. It has been suggested that these pulsationally clumped RR01…