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The Late Stellar Assembly of Massive Cluster Galaxies via Major Merging
Tran, Kim-Vy H.; Moustakas, John; Gonzalez, Anthony H. +3 more
We present multiwavelength observations of the brightest galaxies in four X-ray-luminous groups at z ~ 0.37 that will merge to form a cluster comparable in mass to Coma. Ordered by increasing stellar mass, the four brightest group galaxies (BGGs) present a time sequence where BGG-1, 2, and 3 are in merging systems and BGG-4 is a massive remnant (M…
Evidence of magnetic field wrapping around penumbral filaments
Solanki, S. K.; Lites, B. W.; Borrero, J. M.
We employ high-spatial resolution spectropolarimetric observations from the Solar Optical Telescope on-board the Hinode spacecraft to investigate the fine structure of the penumbral magnetic fields. The Stokes vector of two neutral iron lines at 630 nm is inverted at every spatial pixel to retrieve the depth-dependence of the magnetic field vector…
Suzaku Wide-Band Observations of SN1006
Petre, Rob; Fukazawa, Yasushi; Kokubun, Motohide +17 more
We report on the wide-band spectra of SN1006, as observed by Suzaku. Thermal and nonthermal emissions were successfully resolved thanks to the excellent spectral response of Suzaku's X-ray CCD XIS. The nonthermal emission could not be reproduced by a simple power-law model, but needed a roll-off at 5.7 × 1016Hz = 0.23keV. The roll-off f…
Keck spectroscopy of the faint dwarf elliptical galaxy population in the Perseus Cluster core: mixed stellar populations and a flat luminosity function
Conselice, Christopher J.; Penny, Samantha J.
We present the result of a photometric and Keck low-resolution imaging spectrometer (LRIS) spectroscopic study of dwarf galaxies in the core of the Perseus Cluster, down to a magnitude of MB = -12.5. Spectra were obtained for 23 dwarf-galaxy candidates, from which we measure radial velocities and stellar population characteristics from …
The Off-Disk Thermal Structure of a Polar Coronal Hole
Landi, Enrico
The thermal structure of the coronal portion of coronal holes is a key factor in the modeling of the source regions and acceleration mechanisms of the fast solar wind. Studies aimed at this region are best carried out on observations outside the disk, where the chromosphere and transition region are not included in the line of sight. In the past, …
Stratification of Sunspot Umbral Dots from Inversion of Stokes Profiles Recorded by Hinode
Solanki, S. K.; Lagg, A.; Riethmüller, T. L.
This work aims to constrain the physical nature of umbral dots (UDs) using high-resolution spectropolarimetry. Full Stokes spectra recorded by the spectropolarimeter on Hinode of 51 UDs in a sunspot close to the disk center are analyzed. The height dependence of the temperature, magnetic field vector, and line-of-sight velocity across each UD is o…
The X-ray cycle in the solar-type star HD 81809. XMM-Newton observations and implications for the coronal structure
Schmitt, J. H. M. M.; Orlando, S.; Hall, J. +3 more
Context: The 11-yr cycle is the best known manifestation of the Sun's activity. While chromospheric cycles have been studied in a number of solar-like stars, very little is known about how these are reflected in the cyclical behavior of the coronal X-ray emission in stars other than the Sun.
Aims: Our long-term XMM-Newton program of long-term …
Echelle Long-Slit Optical Spectroscopy of Evolved Stars
Sahai, R.; Sánchez Contreras, C.; Gil de Paz, A. +1 more
We present echelle long-slit optical spectra of a sample of objects evolving off the asymptotic giant branch (AGB), most of them in the preplanetary nebula (PPN) phase, obtained with the ESI and MIKE spectrographs at the 10 m Keck II and 6.5 m Magellan-I telescopes, respectively. The total wavelength range covered with ESI (MIKE) is ~3900-10900 Å …
What is the best method to calculate the solar wind propagation delay?
Haaland, S.; Mailyan, B.; Munteanu, C.
We present a statistical study of propagation times of solar wind discontinuities between Advanced Composition Explorer (ACE) spacecraft orbiting the L1 libration point and the Cluster quartet of spacecraft near the Earth's magnetopause. The propagation times for almost 200 events are compared with the predicted times from four different models. T…
The XRS microcalorimeter spectrometer at the Livermore electron beam ion trap
Boyce, K. R.; Kilbourne, C. A.; Porter, F. S. +9 more
NASAs X-ray spectrometer (XRS) microcalorimeter instrument has been operating at the electron beam ion trap (EBIT) facility at Lawrence Livermore National Laboratory since July of 2000. The spectrometer is currently undergoing its third major upgrade to become an easy to use and extremely high-performance instrument for a broad range of EBIT exper…