Search Publications
Long-term Measurements of Sunspot Magnetic Tilt Angles
Li, Jing; Ulrich, Roger K.
Tilt angles of close to 30,600 sunspots are determined using Mount Wilson daily averaged magnetograms taken from 1974 to 2012, and SOHO/MDI magnetograms taken from 1996 to 2010. Within a cycle, more than 90% of sunspots have a normal polarity alignment along the east-west direction following Hale's law. The median tilts increase with increasing la…
The CHESS Survey of the L1157-B1 Shock Region: CO Spectral Signatures of Jet-driven Bow Shocks
Codella, C.; Ceccarelli, C.; Benedettini, M. +7 more
The unprecedented sensitivity of Herschel coupled with the high resolution of the HIFI spectrometer permits studies of the intensity-velocity relationship I(v) in molecular outflows, over a higher excitation range than possible up to now. Over the course of the CHESS Key Program, we have observed toward the bright bow shock region L1157-B1, the CO…
On Dark Peaks and Missing Mass: A Weak-lensing Mass Reconstruction of the Merging Cluster System A520
Bradač, Maruša; Massey, Richard; Gonzalez, Anthony H. +4 more
Merging clusters of galaxies are unique in their power to directly probe and place limits on the self-interaction cross-section of dark matter. Detailed observations of several merging clusters have shown the intracluster gas to be displaced from the centroids of dark matter and galaxy density by ram pressure, while the latter components are spati…
Characterizing Transition Temperature Gas in the Galactic Corona
Savage, Blair D.; Fox, Andrew J.; Wakker, Bart P. +2 more
We present a study of the properties of the transition temperature (T ~ 105 K) gas in the Milky Way corona, based on the measurements of O VI, N V, C IV, Si IV, and Fe III absorption lines seen in the far-ultraviolet spectra of 58 sight lines to extragalactic targets, obtained with the Far-Ultraviolet Spectroscopic Explorer and the Spac…
Herschel-PACS Observations of Far-IR CO Line Emission in NGC 1068: Highly Excited Molecular Gas in the Circumnuclear Disk
Lutz, D.; Genzel, R.; Poglitsch, A. +13 more
We report the detection of far-IR CO rotational emission from the prototypical Seyfert 2 galaxy NGC 1068. Using Herschel-PACS, we have detected 11 transitions in the J upper = 14-30 (E upper/kB = 580-2565 K) range, all of which are consistent with arising from within the central 10'' (700 pc). The detected transiti…
The Disk-wind-Jet Connection in the Black Hole H 1743-322
Fabian, A. C.; Miller, J. M.; Reynolds, C. S. +6 more
X-ray disk winds are detected in spectrally soft, disk-dominated phases of stellar-mass black hole outbursts. In contrast, compact, steady, relativistic jets are detected in spectrally hard states that are dominated by non-thermal X-ray emission. Although these distinctive outflows appear to be almost mutually exclusive, it is possible that a disk…
Assembly of the Red Sequence in Infrared-selected Galaxy Clusters from the IRAC Shallow Cluster Survey
Dey, Arjun; Jannuzi, Buell; Eisenhardt, Peter R. M. +9 more
We present results for the assembly and star formation histories (SFHs) of massive (~L*) red sequence galaxies (RSGs) in 11 spectroscopically confirmed, infrared-selected galaxy clusters at 1.0 < z < 1.5, the precursors to present-day massive clusters with M ~ 1015 M ⊙. Using rest-frame optical photometry, we investigat…
Behavior of Solar Cycles 23 and 24 Revealed by Microwave Observations
Gopalswamy, N.; Michalek, G.; Shibasaki, K. +3 more
Using magnetic and microwave butterfly diagrams, we compare the behavior of solar polar regions to show that (1) the polar magnetic field and the microwave brightness temperature during solar minimum substantially diminished during the cycle 23/24 minimum compared to the 22/23 minimum. (2) The polar microwave brightness temperature (Tb) seems to b…
Spectroscopic Signature of Alfvén Waves Damping in a Polar Coronal Hole up to 0.4 Solar Radii
Bemporad, A.; Abbo, L.
Between 2009 February 24 and 25, the EUV Imaging Spectrometer (EIS) spectrometer on board the Hinode spacecraft performed special "sit and stare" observations above the south polar coronal hole continuously over more than 22 hr. Spectra were acquired with the 1'' slit placed off-limb covering altitudes up to 0.48 R ⊙ (3.34 × 102
The Rest-frame UV-to-optical Colors and Spectral Energy Distributions of z ~ 4-7 Galaxies
Franx, Marijn; Labbé, Ivo; Bouwens, Rychard J. +4 more
We use the ultra-deep HUDF09 and the deep Early Release Science data from the HST WFC3/IR camera, along with the wide-area Spitzer/IRAC data from GOODS-S to derive spectral energy distributions (SEDs) of star-forming galaxies from the rest-frame UV to the optical over a wide luminosity range (M 1500 ~ -21 to M 1500 ~ -18) fro…