Search Publications
XMM-Newton Observations of the TeV BL Lacertae Object PKS 2155-304 in 2006: Signature of Inverse Compton X-Ray Emission?
Zhang, Y. H.
This paper reports the first discovery of possible inverse Compton (IC) X-ray emission below 10 keV in the typical high-energy peaked BL Lac object (HBL) PKS 2155-304. Two XMM-Newton observations performed in 2006 reveal that the 0.6-10 keV X-ray spectra of the source harden (Δ Γ ~ 0.1-0.3) at break energies of ~4 keV. The concave X-ray spectra of…
On the Origin of Magnetic Helicity in the Solar Corona
Alexander, David; Tian, Lirong
Twenty-three active regions associated with pronounced sigmoidal structure in Yohkoh soft X-ray observations are selected to investigate the origin of magnetic helicity in the solar corona. We calculate the radial magnetic flux of each polarity, the rate of magnetic helicity injection, and total flux of the helicity injection (Δ HLCT) o…
A Jet Associated with the Classical T Tauri Star RY Tauri
Bastien, Pierre; St-Onge, Gilbert
High spatial resolution images have been taken on the Gemini North telescope of the classical T Tauri star RY Tauri. The Hα image, with the continuum properly subtracted, shows a jet extending out to at least 31'' at a position angle of about 295° from the star. A counterjet extending to at least 3.5' in the opposite direction is also visible. The…
Hinode Observations of Chromospheric Brightenings in the Ca II H Line during Small-Scale Flux Emergence Events
Guglielmino, S. L.; Romano, P.; Bellot Rubio, L. R. +1 more
Ca II H emission is a well-known indicator of magnetic activity in the Sun and other stars. It is also viewed as an important signature of chromospheric heating. However, the Ca II H line has not been used as a diagnostic of magnetic flux emergence from the solar interior. Here we report on Hinode observations of chromospheric Ca II H brightenings…
A Universal Decline Law of Classical Novae. III. GQ Muscae 1983
Cassatella, Angelo; Kato, Mariko; Hachisu, Izumi
We present a unified model of infrared (IR), optical, ultraviolet (UV), and X-ray light curves for the 1983 outburst of GQ Muscae (Nova Muscae 1983) and estimate its white dwarf (WD) mass. Based on an optically thick wind model of nova outbursts, we model the optical and IR light curves with free-free emission, and the UV 1455 Å and supersoft X-ra…
Deep Infrared Observations of the Puzzling Central X-Ray Source in RCW 103
Caraveo, P. A.; Bignami, G. F.; Mereghetti, S. +4 more
The object 1E 161348-5055 (1E 1613) is a pointlike, soft X-ray source shining at the center of the 2000 yr old supernova remnant (SNR) RCW 103. It features a puzzling 6.67 hr periodicity and dramatic variability over a timescale of a few years. This, coupled with a young age and the lack of an obvious optical counterpart, makes 1E 1613 a unique so…
Intermittency in the Photosphere and Corona above an Active Region
Wang, Haimin; Yurchyshyn, Vasyl; Abramenko, Valentyna
Recent studies have demonstrated without doubt that the magnetic field in the photosphere and corona is an intermittent structure, opening new views of the underlying physics. In particular, such problems as the existence in the corona of localized areas with extremely strong resistivity (required to explain magnetic reconnection at all scales) an…
Mid-Infrared Spectra of High-Redshift (z > 2) Radio Galaxies
Stern, D.; Fazio, G. G.; Seymour, N. +8 more
We present the first mid-infrared Spitzer/Infrared Spectrograph (IRS) observations of powerful radio galaxies at z > 2. These radio galaxies, 4C +23.56 (z = 2.48) and 6C J1908+7220 (z = 3.53), both show strong mid-infrared continua, but with 6C J1908+7220 also showing strong PAH emission at rest-frame 6.2 and 7.7 µm. In 4C +23.56 we see n…
On the Distance and Reddening of the Starburst Galaxy IC 10
Walker, A. R.; Prada Moroni, P. G.; Degl'Innocenti, S. +16 more
We present deep and accurate optical photometry of the Local Group starburst galaxy IC 10. The photometry is based on two sets of images collected with the Advanced Camera for Surveys and with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. We provide new estimates of the tip of the red giant branch (TRGB) magnitude, m{…
Physical Properties of the AXP 4U 0142+61 from X-Ray Spectral Analysis
Göğüş, Ersin; Güver, Tolga; Özel, Feryal
We analyze archival Chandra and XMM-Newton data of 4U 0142+61 within the context of the surface thermal emission and magnetospheric scattering model. We show that the 4U 0142+61 spectrum can be fit very well with this physical model that contains only four parameters. The system parameters can be tightly constrained from the fits, yielding a surfa…