Search Publications
HST/STIS high resolution echelle spectra of α Centauri A (G2 V)
Pagano, I.; Linsky, J. L.; Valenti, J. +1 more
We describe and analyze HST/STIS observations of the G2 V star α Centauri A (
High-amplitude, long-term X-ray variability in the solar-type star HD 81809: The beginning of an X-ray activity cycle?
Schmitt, J. H. M. M.; Güdel, M.; Harnden, F. R., Jr. +5 more
We present the initial results from our XMM-Newton program aimed at searching for X-ray activity cycles in solar-type stars. HD 81809 is a G2-type star (somewhat more evolved than the Sun, and with a less massive companion) with a pronounced 8.2 yr chromospheric cycle, as evident from from the Mt. Wilson program data. We present here the results f…
Automatic detection of arcs and arclets formed by gravitational lensing
Schindler, S.; Lenzen, F.; Scherzer, O.
We present an algorithm developed particularly to detect gravitationally lensed arcs in clusters of galaxies. This algorithm is suited for automated surveys as well as individual arc detections. New methods are used for image smoothing and source detection. The smoothing is performed by so-called anisotropic diffusion, which maintains the shape of…
Dust and super star clusters in NGC 5253
Sauvage, M.; Vanzi, L.
We present new observations of the famous starburst galaxy NGC 5253 which owes its celebrity to possibly being the youngest and closest starburst galaxy known. Our observations in the infrared and millimeter contribute to shed light on the properties of this interesting object. We have used our new data along with data from the literature to study…
Detection of a companion to the pulsating sdB Feige 48
Heber, U.; Benjamin, R. A.; O'Toole, S. J.
We present the discovery of a binary companion to the pulsating sdB Feige 48. Using HST/STIS and archival FUSE spectra, we measure a period of 0.376±0.003 d and a velocity semi-amplitude of 28.0±0.2 km s-1. This implies that the companion star must either be of very low mass, or the orbit is at low inclination. Combining 2MASS fluxes, t…
A Chandra observation of the old open cluster M 67
Tagliaferri, G.; Belloni, T.; van den Berg, M. +1 more
We present the results of a 47-ks Chandra-ACIS observation of the old open cluster
Balltracking: An highly efficient method for tracking flow fields
Potts, H. E.; Barrett, R. K.; Diver, D. A.
We present a method for tracking solar photospheric flows that is highly efficient, and demonstrate it using high resolution MDI continuum images. The method involves making a surface from the photospheric granulation data, and allowing many small floating tracers or balls to be moved around by the evolving granulation pattern. The results are tes…
I Zw 1 observed with XMM-Newton . Low-energy spectral complexity, iron lines, and hard X-ray flares
Brandt, W. N.; Vaughan, S.; Fabian, A. C. +2 more
We present a 20 ks XMM-Newton observation of the prototypical Narrow-Line Seyfert 1 galaxy I Zw 1. The best-fit model to the data is a double blackbody plus a dominant power-law, on which complex soft absorption (possibly a blended edge or absorption lines) and/or OVII emission are superimposed, as well as strong Fe Kα emission. The iron feature i…
The complex X-ray spectrum of NGC 4507
Bianchi, S.; Matt, G.; D'Ammando, F. +1 more
XMM-Newton and Chandra/HETG spectra of the Compton-thin (NH∼4×1023 cm-2) Seyfert 2 galaxy, NGC 4507, are analyzed and discussed. The main results are: a) the soft X-ray emission is rich in emission lines; an (at least) two-zone photoionization region is required to explain the large range of ionization states; b) t…
XMM-Newton spectral and timing observations of the millisecond pulsar PSR J0218+4232
Webb, N. A.; Barret, D.; Olive, J. -F.
We present XMM-Newton MOS imaging and PN timing data of the millisecond pulsar