Search Publications
Galaxy Structure in the Ultraviolet: The Dependence of Morphological Parameters on Rest-frame Wavelength
Conselice, Christopher J.; Madore, Barry F.; Windhorst, Rogier A. +5 more
Evolutionary studies that compare galaxy structure as a function of redshift are complicated by the fact that any particular galaxy’s appearance depends in part on the rest-frame wavelength of the observation. This leads to the necessity for a “morphological k-correction” between different passbands, especially when comparing the rest-frame optica…
The MOSDEF Survey: The Nature of Mid-infrared Excess Galaxies and a Comparison of IR and UV Star Formation Tracers at z ∼ 2
Siana, Brian; Azadi, Mojegan; Coil, Alison +11 more
We present an analysis using the MOSFIRE Deep Evolution Field (MOSDEF) survey on the nature of “MIR-excess” galaxies, which have star formation rates (SFRs) inferred from mid-infrared (MIR) data that are substantially elevated relative to those estimated from dust-corrected UV data. We use a sample of ∼200 galaxies and active galactic nuclei (AGNs…
The Spectral and Environment Properties of z ∼ 2.0-2.5 Quasar Pairs
Hennawi, Joseph F.; Rafelski, Marc; Neeleman, Marcel +5 more
We present the first results from our survey of intervening and proximate Lyman limit systems (LLSs) at z ∼ 2.0-2.5 using the Wide Field Camera 3 on board the Hubble Space Telescope. The quasars in our sample are projected pairs with proper transverse separations R ⊥ ≤ 150 kpc and line-of-sight velocity separations ≲11,000 km s-1
A Study of a Compound Solar Eruption with Two Consecutive Erupting Magnetic Structures
Chintzoglou, Georgios; Zhang, Jie; Dhakal, Suman K.
We report a study of a compound solar eruption that was associated with two consecutively erupting magnetic structures and correspondingly two distinct peaks, during impulsive phase, of an M-class flare (M8.5). Simultaneous multi-viewpoint observations from SDO, GOES and STEREO-A show that this compound eruption originated from two pre-existing si…
K 2 Ultracool Dwarfs Survey. IV. Monster Flares Observed on the Young Brown Dwarf CFHT-BD-Tau 4
Mullan, D. J.; Burgasser, Adam J.; Gizis, John E. +4 more
We present photometric measurements of two superflares observed on a very young brown dwarf, CFHT-BD-Tau 4, observed during Campaign 13 of the Kepler K 2 mission. The stronger of the two superflares brightened by a factor of ∼48 relative to the quiescent photospheric level, with an increase in Kepler magnitude {{Δ }}\tilde{{K}p}=-4.20. …
Demonstration of a Novel Method for Measuring Mass-loss Rates for Massive Stars
Kobulnicky, Henry A.; Povich, Matthew S.; Chick, William T.
The rate at which massive stars eject mass in stellar winds significantly influences their evolutionary path. Cosmic rates of nucleosynthesis, explosive stellar phenomena, and compact object genesis depend on this poorly known facet of stellar evolution. We employ an unexploited observational technique for measuring the mass-loss rates of O and ea…
Revealing the Broad Line Region of NGC 1275: The Relationship to Jet Power
Gurwell, Mark A.; Punsly, Brian; Marziani, Paola +2 more
NGC 1275 is one of the most conspicuous active galactic nuclei (AGN) in the local universe. The radio jet currently emits a flux density of ∼10 Jy at ∼1 mm wavelengths, down from the historic high of ∼65 Jy in 1980. Yet, the nature of the AGN in NGC 1275 is still controversial. It has been debated whether this is a broad emission line (BEL) Seyfer…
Consistent Iron Abundances Derived from Neutral and Singly Ionized Iron Lines in Ultraviolet and Optical Spectra of Six Warm Metal-poor Stars
Roederer, Ian U.; Sneden, Christopher; Cowan, John J. +3 more
Neutral Fe lines in metal-poor stars yield conflicting abundances depending on whether and how deviations from local thermodynamic equilibrium (LTE) are considered. We have collected new high-resolution and high signal-to-noise ultraviolet (UV) spectra of three warm dwarf stars with [Fe/H] ≈ -2.9 with the Space Telescope Imaging Spectrograph on th…
Vertical Oscillation of a Coronal Cavity Triggered by an EUV Wave
Ji, H. S.; Zhang, Q. M.
In this paper, we report our multiwavelength observations of the vertical oscillation of a coronal cavity on 2011 March 16. The elliptical cavity with an underlying horn-like quiescent prominence was observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. The width and height of the cavity are 150″ and 240″, and the c…
NLTE Analysis of Copper Lines in Different Stellar Populations
Zhao, G.; Shi, J. R.; Yan, H. L. +1 more
The copper abundances of 29 metal-poor stars are determined based on the high-resolution, high-signal-to-noise ratio spectra from the UVES spectrograph at the ESO VLT telescope. Our sample consists of the stars of the Galactic halo, thick- and thin-disk, with [Fe/H] ranging from ∼-3.2 to ∼0.0 dex. The non-local thermodynamic equilibrium (NLTE) eff…