Search Publications
Young Energetic PSR J1617-5055, Its Nebula, and TeV Source HESS J1616-508
Pavlov, G. G.; Kargaltsev, O.; Wong, J. A.
We observed the young pulsar J1617-5055 with the Chandra ACIS detector for 60 ks. In addition to the pulsar, the X-ray images show a faint pulsar wind nebula (PWN) seen up to ~1' from the pulsar. Deconvolution and reconstruction of the image reveal a brighter compact PWN component of ~1'' size. The total PWN luminosity in the 0.5-8 keV band, L
Jets in Polar Coronal Holes
Doyle, J. G.; Erdélyi, R.; Banerjee, D. +2 more
Here, we explore the nature of small-scale jet-like structures and their possible relation to explosive events and other known transient features, like spicules and macrospicules, using high-resolution spectroscopy obtained with the Solar and Heliospheric Observatory/Solar Ultraviolet Measurements of Emitted Radiation instrument. We present a high…
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…