Search Publications
Constraints on Long-period Planets from an L'- and M-band Survey of Nearby Sun-like Stars: Observations
Heinze, A. N.; Kenworthy, Matthew; Sivanandam, Suresh +3 more
We present the observational results of an L'- and M-band adaptive optics imaging survey of 54 nearby, Sun-like stars for extrasolar planets, carried out using the Clio camera on the MMT. We have concentrated more strongly than all other planet-imaging surveys to date on very nearby F, G, and K stars, prioritizing stellar proximity higher than you…
Observational Aspects of the Three-dimensional Coronal Structure Over a Solar Activity Cycle
Morgan, Huw; Habbal, Shadia Rifai
Solar rotational tomography is applied to almost eleven years of Large Angle Spectrometric Coronagraph C2/Solar and Heliospheric Observatory data, revealing for the first time the behavior of the large-scale coronal density structures, also known as streamers, over almost a full solar activity cycle. This study gives an overview of the main result…
The Vertical Component of the Supergranular Motion
Birch, A. C.; Duvall, T. L., Jr.
Supergranules are observed at the solar photosphere as a cellular horizontal flow pattern with flow diverging from cell centers and converging on cell boundaries. Clark & Johnson calculated that mass conservation leads to an expected vertical flow of only 10 m s-1, which has been difficult to observe. In the present work, Doppler im…
Star Formation in the Bullet Cluster. I. The Infrared Luminosity Function and Star Formation Rate
Gonzalez, Anthony H.; Zaritsky, Dennis; Markevitch, Maxim +2 more
The Bullet Cluster is a massive galaxy cluster at z = 0.297 undergoing a major supersonic (Mach 3) merger event. Using data from Spitzer MIPS and the Infrared Array Camera, optical imaging, and optical spectroscopy, we present the global star formation rate (SFR) of this unique cluster. Using a 90% spectroscopically complete sample of 37 star-form…
Distribution of Magnetic Bipoles on the Sun over Three Solar Cycles
Pevtsov, Alexei A.; Tlatov, Andrey G.; Vasil'eva, Valerya V.
We employ synoptic full disk longitudinal magnetograms to study latitudinal distribution and orientation (tilt) of magnetic bipoles in the course of sunspot activity during cycles 21, 22, and 23. The data set includes daily observations from the National Solar Observatory at Kitt Peak (1975-2002) and Michelson Doppler Imager on board the Solar and…
Radio and Deep Chandra Observations of the Disturbed Cool Core Cluster Abell 133
Sarazin, C. L.; Forman, W. R.; Murray, S. S. +4 more
We present results based on new Chandra and multi-frequency radio observations of the disturbed cool core cluster Abell 133. The diffuse gas has a complex bird-like morphology, with a plume of emission extending from two symmetric wing-like features. The plume is capped with a filamentary radio structure that has been previously classified as a ra…
A Study of the Build-up, Initiation, and Acceleration of 2008 April 26 Coronal Mass Ejection Observed by STEREO
Cheng, X.; Ding, M. D.; Zhang, J.
In this paper, we analyze the full evolution, from a few days prior to the eruption to the initiation, final acceleration, and propagation, of the coronal mass ejection (CME) that occurred on 2008 April 26 using the unprecedented high cadence and multi-wavelength observations by the Solar Terrestrial Relations Observatory. There existed frequent f…
The Galaxy-wide Distributions of Mean Electron Density in the H II Regions of M51 and NGC 4449
Beckman, John E.; Gutiérrez, Leonel
Using Advanced Camera for Surveys-Hubble Space Telescope images to yield continuum-subtracted photometric maps in Hα of the Sbc galaxy M51 and the dwarf irregular galaxy NGC 4449, we produced extensive (over 2000 regions for M51 and over 200 regions for NGC 4449) catalogs of parameters of their H II regions: their Hα luminosities, equivalent radii…
Production of High-temperature Plasmas During the Early Phases of a C9.7 Flare
Harra, Louise K.; Hara, Hirohisa; Watanabe, Tetsuya +1 more
Explosive chromospheric evaporation is predicted from some current solar flare models. In this paper, we analyze a flare with high time cadence raster scans with the EUV Imaging Spectrometer (EIS) on board the Hinode spacecraft. This observation covers an area of 240'' × 240'', with the 1'' slit in about 160 s. The early phases of a C9.7 flare tha…
Changes of the Solar Meridional Velocity Profile During Cycle 23 Explained by Flows Toward the Activity Belts
Schüssler, M.; Cameron, R. H.
The solar meridional flow is an important ingredient in Babcock-Leighton type models of the solar dynamo. Global variations of this flow have been suggested to explain the variations in the amplitudes and lengths of the activity cycles. Recently, cycle-related variations in the amplitude of the P 1 2 term in the Legendre deco…