Search Publications
The Magnetic Topology of Coronal Mass Ejection Sources
Winebarger, Amy R.; Warren, Harry P.; Ugarte-Urra, Ignacio
In an attempt to test current initiation models of coronal mass ejections (CMEs), with an emphasis on the magnetic breakout model, we inspect the magnetic topology of the sources of 26 CME events in the context of their chromospheric and coronal response in an interval of approximately 9 hr around the eruption onset. First we perform current-free …
Large Amounts of Optically Obscured Star Formation in the Host Galaxies of Some Type 2 Quasars
Armus, L.; Seymour, N.; Canalizo, G. +5 more
We present Hubble Space Telescope images and spectral energy distributions from optical to infrared wavelengths for a sample of six 0.3<z<0.8 type 2 quasars selected in the mid-infrared using data from the Spitzer Space Telescope. All the host galaxies show some signs of disturbance. Most seem to possess dusty, star-forming disks. The disk i…
Stellar Kinematics in the Complicated Inner Spheroid of M31: Discovery of Substructure along the Southeastern Minor Axis and Its Relationship to the Giant Southern Stream
Gilbert, Karoline M.; Majewski, Steven R.; Guhathakurta, Puragra +9 more
We present the discovery of a kinematically cold stellar population along the southeastern minor axis of the Andromeda galaxy (M31) that is likely the forward continuation of M31's giant southern stream. This discovery was made during an on-going spectroscopic survey of M31 red giant branch (RGB) stars using the DEIMOS instrument on the Keck II 10…
The Distances to Open Clusters from Main-Sequence Fitting. IV. Galactic Cepheids, the LMC, and the Local Distance Scale
Pinsonneault, Marc H.; Terndrup, Donald M.; An, Deokkeun
We derive the basic properties of seven Galactic open clusters containing Cepheids and construct their period-luminosity (P-L) relations. For our cluster main-sequence fitting we extend previous Hyades-based empirical color-temperature corrections to hotter stars using the Pleiades as a template. We use BVICJHKs data to test …
Strong Dusty Bursts of Star Formation in Galaxies Falling into the Cluster RX J0152.7-1357
Rigby, J. R.; Rieke, G. H.; Marcillac, D. +1 more
We have observed the cluster RX J0152.7-1357 (z~0.83) at 24 µm with the Multiband Imaging Photometer for Spitzer (MIPS). We detected 22 sources associated with spectroscopically confirmed cluster members, while 10 more have photometric redshifts compatible with membership. Two of the 32 likely cluster members contain obvious active nuclei, w…
IR Observations of MS 1054-03: Star Formation and Its Evolution in Rich Galaxy Clusters
Tran, Kim-Vy H.; Rieke, George H.; Rieke, Marcia J. +6 more
We study the IR properties of galaxies in the cluster MS 1054-03 at z=0.83 by combining MIPS 24 µm data with spectra of more than 400 galaxies and a very deep K-band-selected catalog. Nineteen IR cluster members are selected spectroscopically, and an additional 15 are selected by their photometric redshifts. We derive the IR luminosity funct…
Chemical Abundances in an AGN Environment: X-Ray/UV Campaign on the Markarian 279 Outflow
Laor, Ari; Scott, Jennifer E.; Kriss, Gerard A. +11 more
We present the first reliable determination of chemical abundances in an active galactic nucleus (AGN) outflow. The abundances are extracted from the deep and simultaneous Far Ultraviolet Spectroscopic Explorer (FUSE) and Hubble Space Telescope (HST) STIS observations of Mrk 279. This data set is exceptional for its high signal-to-noise ratio, unb…
Stellar Populations across the NGC 4244 Truncated Galactic Disk
de Jong, Roelof S.; Ferguson, H. C.; Dalcanton, J. J. +12 more
We use the Hubble Space Telescope ACS to study the resolved stellar populations of the nearby, nearly edge-on galaxy NGC 4244 across its outer disk surface density break. The stellar photometry allows us to study the distribution of different stellar populations and reach very low equivalent surface brightnesses. We find that the break occurs at t…
Hubble Space Telescope Advanced Camera for Surveys Coronagraphic Observations of the Dust Surrounding HD 100546
Ford, H. C.; Illingworth, G. D.; Ardila, D. R. +3 more
We present HST ACS coronagraphic observations of HD 100546, a B9.5 star, 103 pc away from the Sun, taken in the F435W, F606W, and F814W bands. Scattered light is detected up to 14" from the star. The observations are consistent with the presence of an extended flattened nebula with the same inclination as the inner disk. The well-known ``spiral ar…
The WEBT Campaign on the Blazar 3C 279 in 2006
Lee, C. -U.; Nishiyama, S.; Mirabal, N. +77 more
The quasar 3C 279 was the target of an extensive multiwavelength monitoring campaign from 2006 January through April. An optical-IR-radio monitoring campaign by the Whole Earth Blazar Telescope (WEBT) collaboration was organized around target-of-opportunity X-ray and soft γ-ray observations with Chandra and INTEGRAL in 2006 mid-January, with addit…