Search Publications
The Early Early Type: Discovery of a Passive Galaxy at z spec ~ 3
Cimatti, A.; Daddi, E.; Béthermin, M. +6 more
We present the discovery of a massive, quiescent galaxy at z = 2.99. We have obtained an Hubble Space Telescope WFC3 spectrum of this object and measured its redshift from the detection of a deep 4000 Å break consistent with an old population and a high metallicity. By stellar population modeling of both its grism spectrum and broadband photometry…
Hinode/EIS Spectroscopic Validation of Very Hot Plasma Imaged with the Solar Dynamics Observatory in Non-flaring Active Region Cores
Testa, Paola; Reale, Fabio
We use coronal imaging observations with the Solar Dynamics Observatory/Atmospheric Imaging Assembly (AIA), and Hinode/Extreme-ultraviolet Imaging Spectrometer (EIS) spectral data to explore the potential of narrowband EUV imaging data for diagnosing the presence of hot (T >~ 5 MK) coronal plasma in active regions. We analyze observations of tw…
Variability and Star Formation in Leo T, the Lowest Luminosity Star-forming Galaxy Known Today
Cignoni, Michele; Marconi, Marcella; Ripepi, Vincenzo +5 more
We present results from the first combined study of variable stars and star formation history (SFH) of the Milky Way "ultra-faint" dwarf (UFD) galaxy Leo T, based on F606W and F814W multi-epoch archive observations obtained with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. We have detected 14 variable stars in the galaxy.…
Rapid Sunspot Rotation Associated with the X2.2 Flare on 2011 February 15
Yang, Jiayan; Hong, Junchao; Zheng, Ruisheng +3 more
We present observations of sunspot evolution associated with the first X-class flare of the present solar cycle 24, which occurred in AR 11158 on 2011 February 15. The active region consisted of four emerging bipoles that showed complicated sunspot motion. The preceding spot of a bipole underwent the fastest movement. It not only passed through th…
A Brightest Cluster Galaxy with an Extremely Large Flat Core
Donahue, Megan; Broadhurst, Tom; Moustakas, John +14 more
Hubble Space Telescope images of the galaxy cluster A2261, obtained as part of the Cluster Lensing And Supernova survey with Hubble, show that the brightest galaxy in the cluster, A2261-BCG, has the largest core yet detected in any galaxy. The cusp radius of A2261-BCG is 3.2 kpc, twice as big as the next largest core known, and ~3 × bigger than th…
A Reverberation Lag for the High-ionization Component of the Broad-line Region in the Narrow-line Seyfert 1 Mrk 335
Skowron, J.; Kochanek, C. S.; Horne, Keith +37 more
We present the first results from a detailed analysis of photometric and spectrophotometric data on the narrow-line Seyfert 1 (NLS1) galaxy Mrk 335, collected over a 120 day span in the fall of 2010. From these data we measure the lag in the He II λ4686 broad emission line relative to the optical continuum to be 2.7 ± 0.6 days and the lag in the H…
The Progenitor of the Type Ia Supernova that Created SNR 0519-69.0 in the Large Magellanic Cloud
Schaefer, Bradley E.; Pagnotta, Ashley; Edwards, Zachary I.
Models for the progenitor systems of Type Ia supernovae can be divided into double-degenerate systems, which contain two white dwarfs, and single-degenerate systems, which contain one white dwarf plus one companion star (either a red giant, a subgiant, or a >1.16 M ⊙ main-sequence star). The white dwarf is destroyed in the supernova …
Measuring the Abundance of Sub-kilometer-sized Kuiper Belt Objects Using Stellar Occultations
Livio, Mario; Nelan, Edmund P.; Gal-Yam, Avishay +6 more
We present here the analysis of about 19,500 new star hours of low ecliptic latitude observations (|b| <= 20°) obtained by the Hubble Space Telescope's Fine Guidance Sensors over a time span of more than nine years, which is in addition to the ~12, 000 star hours previously analyzed by Schlichting et al. Our search for stellar occultations by s…
Systematic Investigation of Solar Modulation of Galactic Protons for Solar Cycle 23 Using a Monte Carlo Approach with Particle Drift Effects and Latitudinal Dependence
Boella, G.; Gervasi, M.; Grandi, D. +8 more
A propagation model of galactic cosmic protons through the heliosphere was implemented using a two-dimensional Monte Carlo approach to determine the differential intensities of protons during solar cycle 23. The model includes the effects due to the variation of solar activity during the propagation of cosmic rays from the boundary of the heliopau…
Galaxy Disks Do Not Need to Survive in the ΛCDM Paradigm: The Galaxy Merger Rate Out to z ~ 1.5 from Morpho-kinematic Data
Flores, H.; Hammer, F.; Puech, M. +5 more
About two-thirds of present-day, large galaxies are spirals such as the Milky Way or Andromeda, but the way their thin rotating disks formed remains uncertain. Observations have revealed that half of their progenitors, six billion years ago, had peculiar morphologies and/or kinematics, which exclude them from the Hubble sequence. Major mergers, i.…