Search Publications
Evidence for particle acceleration in the magnetospheric cusp
Chen, J.
New evidence reveals that the charged particles can be energized locally in the magnetospheric cusp. The power spectral density of the cusp magnetic fluctuations shows increases by up to four orders of magnitude in comparison to an adjacent region. Large fluctuations of the cusp electric fields have been observed with an amplitude of up to 350 mV/…
Unlensing HST observations of the Einstein ring 1RXS J1131-1231: a Bayesian analysis
Brewer, B. J.; Lewis, G. F.
We present a source and lens reconstruction for the optical Einstein ring gravitational lens system RXS J1131-1231. We resolve detail in the source, which is the host galaxy of a z = 0.658 quasar, down to a resolution of 0.045 arcsec (this is the size of the smallest conclusively resolved structures, rather than the pixel scale), using a Bayesian …
Properties of nuclear star clusters
Böker, Torsten
Over the last decade, HST imaging studies have revealed that the centers of most galaxies are occupied by massive, yet compact, stellar clusters. These 'nuclear star clusters' (NSCs) are found in a wide range of Hubble types, suggesting that their formation is intricately linked to galaxy evolution. In this review, I briefly summarize what has bee…
Ultraviolet Spectroscopy of HD 44179
Sitko, Michael L.; Bernstein, Lawrence S.; Glinski, Robert J.
We have reanalyzed the ultraviolet spectrum of HD 44179, the central star(s) of the Red Rectangle Nebula, providing improved estimates of the column density, rotational, and vibrational temperatures of the 4th Positive A-X system of CO in absorption. The flux shortward of 2200 Å is a complex blend of CO features with no discernible stellar photosp…
May Day! Coronal Loop Temperatures from the Hinode EUV Imaging Spectrometer
Schmelz, J. T.; Scott, J.; Rightmire, L. A.
Data from the EUV Imaging Spectrometer on Hinode taken on 2007 May 1 (May Day) are used to investigate the thermal properties of a coronal loop in AR 10953. For background subtraction, we have taken cuts across the loop near the apex and the footpoint where the background is relatively simple. Three density-sensitive line ratios give statistically…
Detection of blueshifted emission and absorption and a relativistic iron line in the X-ray spectrum of ESO323-G077
Bianchi, S.; Schartel, N.; Santos-Lleó, M. +4 more
We report on the X-ray observation of the Seyfert 1 galaxy ESO323-G077 performed with XMM-Newton. The EPIC spectra show a complex spectrum with conspicuous absorption and emission features. The continuum emission can be modelled with a power law with an index of 1.99 +/- 0.02 in the whole XMM-Newton energy band, marginally consistent with typical …
A Survey of 3.3 µm PAH Emission in Planetary Nebulae
McLean, Ian S.; Smith, Erin C. D.
Results are presented from a pilot survey of 3.3 µm PAH emission from planetary nebulae using FLITECAM, an instrument intended for airborne astronomy with SOFIA. The observations were made during ground-based commissioning of FLITECAM's spectroscopic mode at the 3 m Shane Telescope at Lick Observatory. Direct-ruled KRS-5 grisms were used to …
Fourier-resolved energy spectra of the Narrow-Line Seyfert 1 Mkn 766
Papadakis, I. E.; Turner, T. J.; Arévalo, P. +4 more
We compute Fourier-resolved X-ray spectra of the Seyfert 1 Markarian 766 to study the shape of the variable components contributing to the 0.3-10 keV energy spectrum and their time-scale dependence. The fractional variability spectra peak at 1-3 keV, as in other Seyfert 1 galaxies, consistent with either a constant contribution from a soft excess …
The microbial case for Mars and its implication for human expeditions to Mars
Horneck, Gerda
Mars is considered as key target for the search of life beyond the Earth. As well as carbon based chemistry and an adequate energy source, water in liquid phase has been considered a prerequisite for habitability. By analogy with terrestrial extremophilic microbial communities, e.g., those thriving in arid, cold, salty environments and/or those ex…
On properties of radio-rich coronal mass ejections
Mittal, Nishant; Sharma, Joginder; Tomar, Vivek +1 more
We have studied properties of the radio-rich coronal mass ejections (CMEs) (observed during 1997–2006) which produce type II (1–14 MHz) i.e. decametric–hectometric or DH radio burst. These DH CMEs are relatively faster and wider than the normal CMEs. The average speed and apparent width of these CMEs is 1048 km/s and 98°, respectively. Majority (a…