Search Publications
Two More Disk Galaxies with Global Gas Counterrotation
Moiseev, A. V.; Sil'chenko, O. K.; Afanasiev, V. L.
We report a discovery of extended counterrotating gaseous disks in early-type disk galaxies NGC 2551 and NGC 5631. To find them, we have undertaken complex spectral observations including integral-field spectroscopy for the central parts of the galaxies and long-slit deep spectroscopy to probe the external parts. The line-of-sight velocity fields …
Solar Magnetic Field Signatures in Helioseismic Splitting Coefficients
Basu, Sarbani; Antia, H. M.; Baldner, Charles S. +1 more
Normal modes of oscillation of the Sun are useful probes of the solar interior. In this work, we use the even-order splitting coefficients to study the evolution of magnetic fields in the convection zone over solar cycle 23, assuming that the frequency splitting is only due to rotation and a large-scale magnetic field. We find that the data are be…
Dipolar Evolution in a Coronal Hole Region
Yang, Shuhong; Zhang, Jun; Borrero, Juan Manuel
Using observations from the Solar and Heliospheric Observatory, the Solar Terrestrial Relations Observatory, and Hinode, we investigate magnetic field evolution in an equatorial coronal hole region. Two dipoles emerge one by one. The negative element of the first dipole disappears due to the interaction with the positive element of the second dipo…
Does a Polar Coronal Hole's Flux Emergence Follow a Hale-Like Law?
Golub, L.; DeLuca, E. E.; Savcheva, A. +1 more
Recent increases in spatial and temporal resolution for solar telescopes sensitive to EUV and X-ray radiation have revealed the prevalence of transient jet events in polar coronal holes. Using data collected by the X-Ray Telescope on Hinode, Savcheva et al. confirmed the observation, made first by the Soft X-ray Telescope on Yohkoh, that some jets…
Spitzer Observations of a Gravitationally Lensed Quasar, QSO 2237+0305
Gorjian, Varoujan; Agol, Eric; Gogarten, Stephanie M. +1 more
The four-image gravitationally lensed quasar QSO 2237+0305 is microlensed by stars in the lens galaxy. The amplitude of microlensing variability can be used to infer the relative size of the quasar as a function of wavelength; this provides a test of quasar models. Toward this end, we present Spitzer Space Telescope Infrared Spectrograph and Infra…
Observations of the Magnetic Reconnection Signature of an M2 Flare on 2000 March 23
Zhang, Jun; Li, Leping
Multiwavelength observations of an M 2.0 flare event on 2000 March 23 in the NOAA active region 8910 provide us a good chance to study the detailed structure and dynamics of the magnetic reconnection region. In the process of the flare, extreme-ultraviolet (EUV) loops displayed two types of sideward motions upon a loop-top hard X-ray source with a…
Low-Power Radio Galaxies in the Distant Universe: A Search for FR I at 1 < z < 2 in the Cosmos Field
Sparks, W. B.; Chiaberge, Marco; Tremblay, Grant +3 more
We present a search for FR I radio galaxies between 1 < z < 2 in the COSMOS field. In absence of spectroscopic redshift measurements, the selection method is based on multiple steps which make use of both radio and optical constraints. The basic assumptions are that (1) the break in radio power between low-power FR Is and the more powerful F…
The Radial Extent of the Double Subgiant Branch in NGC 1851
Rejkuba, M.; Zoccali, M.; Pancino, E. +3 more
Recent Hubble Space Telescope (HST)/Advanced Camera for Surveys (ACS) observations revealed the presence of a double subgiant branch (SGB) in the core of the Galactic globular cluster NGC 1851. This peculiarity was tentatively explained by the presence of a second population with either an age difference of about 1 Gyr, or a higher C+N+O abundance…
Nonthermal X-ray Emission in the N11 Superbubble in the Large Magellanic Cloud
Chu, Y. -H.; Williams, R. M.; Maddox, L. A. +1 more
We present the results of X-ray spectral analysis of the superbubble (SB) around the OB association LH9 in the H II complex N11 in the Large Magellanic Cloud. Using observations from Suzaku, we have modeled the X-ray emission over the energy range 0.2-7.5 keV. We constrained the thermal spectrum below 2 keV using a thermal plasma model found in a …
Direct Observation of a Corotating Interaction Region by Three Spacecraft
Tappin, S. J.; Howard, T. A.
White-light observations of interplanetary disturbances have been dominated by interplanetary coronal mass ejections (ICMEs). This is because the other type of disturbance, the corotating interaction region (CIR), has proved difficult to detect using white-light imagers. Recently, a number of papers have appeared presenting CIR observations using …