Search Publications

Optical Identification of the X-Ray Burster X1746-370 in the Globular Cluster NGC 6441

Anderson, Scott F.; Margon, Bruce; Deutsch, Eric W. +2 more

We find convincing observational evidence to confirm the optical identification of the X-ray burster X1746-370, located in the globular cluster NGC 6441. Chandra HRC-I imaging yields a much improved X-ray position for the source, which we show to be fully consistent with our rederived position of a UV-excess star, U1, in the same astrometric refer…

Evidence of a Strong N V/C IV Correlation between Emission and Absorption Lines in Active Galactic Nuclei

Green, Paul J.; Kuraszkiewicz, Joanna K.

The narrow absorption lines (NALs) that are seen in the rest-frame ultraviolet near the systemic redshift of active galactic nuclei (AGNs) are not always intrinsic to the near-nuclear region but may originate in the host galaxy or in neighboring galaxies intervening along the line of sight. A variety of criteria have been sought-and several identi…

Ion Effective Temperatures in Polar Coronal Holes: Observations versus Ion-Cyclotron Resonance

Patsourakos, S.; Habbal, S. R.; Hu, Y. Q.

The resonant cyclotron interaction between ion-cyclotron waves and solar wind species is considered nowadays to be a strong candidate for heating and acceleration of protons, α-particles, and heavy ions. A crucial physical parameter for determining the amount and the location of significant heating and acceleration, which the different solar wind …

New radio instrumentation for the study of sunspots and starspots

White, S. M.

Much of the radio emission from the Sun and similar stars depends directly on magnetic fields for its origin. For this reason, radio emission contains important diagnostic information on solar and stellar magnetic fields. This paper reviews radio measurements of coronal magnetic fields and discusses new radio instrumentation that will exploit this…

Variability in the solar constant from irradiances shortward of Lyman-Alpha

Tobiska, W. Kent

The variation in the solar constant, S(t), is reproduced by the SOLAR2000 Research Grade v1.05 empirical solar irradiance model and is described for 5 solar cycles between cycles 18 and 23 (February 14, 1947 through May 31, 2000). This solar constant variation is dependent upon the derivation data sets and the formulation of SOLAR2000 which are de…

Atmospheric Dynamics and Magnetic Activity Associated With A Coronal Mass Ejection

Zhang, Jun; Wang, Jingxiu; Yang, Zhiliang +1 more

By using multi-wavelength observations, we explored the atmospheric dynamics and the surface magnetic activity in NOAA 9026, which were associated with the initiation of a halo coronal mass ejection (CME) on 6 June, 2000. In an interval of less than two hours, two X-class X-ray flares took place successively, each along with one eruption of a fila…

Astrometric Orbits from a Direct Combination of Ground-Based Catalogs with the Hipparcos Catalog

Kiyaeva, O. V.; Goncharov, G. A.

Detectability and characteristics of the 2.223 MeV line emission from nearby X-ray binaries

Guessoum, N.; Jean, P.

We present an application and an improvement of the model of Jean & Guessoum (\cite{JG01}) for the production of the 2.223 MeV line resulting from the capture of neutrons in the atmosphere of the secondary in an X-ray binary system. In this model, the neutrons are produced in the accretion disk around the compact primary star and radiated in a…

The solar corona in cycle 23

Del Zanna, G.; Fludra, A.; Thompson, W. T. +1 more

The Coronal Diagnostic Spectrometer (CDS) on SOHO has been recording EUV spectra and monitoring time variability of EUV line intensities, electron temperature and density in the low solar corona during the rising part of Cycle 23. The four-year data set includes daily synoptic observations in four EUV lines along the central meridian since April 1…

A Reexamination of the ``Planetary'' Lensing Events in M22

Anderson, Jay; Sahu, Kailash C.; King, Ivan R.

We have carried out a further analysis of the tentative, short-term brightenings reported by Sahu and coworkers, which were suggested to be possible lensing of Galactic bulge stars by free-floating planets in the globular cluster M22. Closer examination shows that-unlikely as it may seem-small, pointlike cosmic rays had hit very close to the same …