Search Publications
CANDELS Observations of the Structural Properties of Cluster Galaxies at z = 1.62
Wuyts, S.; Ferguson, H. C.; Finkelstein, S. L. +25 more
We discuss the structural and morphological properties of galaxies in a z = 1.62 proto-cluster using near-IR imaging data from Hubble Space Telescope Wide Field Camera 3 data of the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS). The cluster galaxies exhibit a clear color-morphology relation: galaxies with colors of quiescent s…
Not Dead Yet: Cool Circumgalactic Gas in the Halos of Early-type Galaxies
Tripp, Todd M.; Prochaska, J. Xavier; Sembach, Kenneth R. +10 more
We report new observations of circumgalactic gas in the halos of early-type galaxies (ETGs) obtained by the COS-Halos Survey with the Cosmic Origins Spectrograph on board the Hubble Space Telescope. We find that detections of H I surrounding ETGs are typically as common and strong as around star-forming galaxies, implying that the total mass of ci…
Verifying Asteroseismically Determined Parameters of Kepler Stars Using Hipparcos Parallaxes: Self-consistent Stellar Properties and Distances
Christensen-Dalsgaard, J.; Weiss, A.; García, R. A. +24 more
Accurately determining the properties of stars is of prime importance for characterizing stellar populations in our Galaxy. The field of asteroseismology has been thought to be particularly successful in such an endeavor for stars in different evolutionary stages. However, to fully exploit its potential, robust methods for estimating stellar param…
The Initial Mass Function of the Orion Nebula Cluster across the H-burning Limit
Henning, T.; Robberto, M.; Da Rio, N. +2 more
We present a new census of the Orion Nebula Cluster over a large field of view (gsim 30' × 30'), significantly increasing the known population of stellar and substellar cluster members with precisely determined properties. We develop and exploit a technique to determine stellar effective temperatures from optical colors, nearly doubling the previo…
Chandra/HETGS Observations of the Brightest Flare Seen from Sgr A*
Miller, J. M.; Nowak, M. A.; Grosso, N. +10 more
Starting in 2012, we began an unprecedented observational program focused on the supermassive black hole in the center of our Galaxy, Sgr A*, utilizing the High Energy Transmission Grating Spectrometer (HETGS) instrument on the Chandra X-Ray Observatory. These observations will allow us to measure the quiescent X-ray spectra of Sgr A* for the firs…
Response of the Photospheric Magnetic Field to the X2.2 Flare on 2011 February 15
Liu, Yang; Liu, Chang; Wang, Haimin +3 more
It is well known that the long-term evolution of the photospheric magnetic field plays an important role in building up free energy to power solar eruptions. Observations, despite being controversial, have also revealed a rapid and permanent variation of the photospheric magnetic field in response to the coronal magnetic field restructuring during…
Deep Near-infrared Spectroscopy of Passively Evolving Galaxies at z >~ 1.4
Cimatti, A.; Daddi, E.; Sanders, D. B. +21 more
We present the results of new near-IR spectroscopic observations of passive galaxies at z >~ 1.4 in a concentration of BzK-selected galaxies in the COSMOS field. The observations have been conducted with Subaru/MOIRCS, and have resulted in absorption lines and/or continuum detection for 18 out of 34 objects. This allows us to measure spectrosco…
How Do Star-forming Galaxies at z > 3 Assemble Their Masses?
Papovich, Casey; Ferguson, Henry C.; Giavalisco, Mauro +8 more
We investigate how star-forming galaxies typically assemble their masses at high redshift. Taking advantage of the deep multi-wavelength coverage of the GOODS data set, we select two of the largest samples of high-redshift star-forming galaxies based on their UV colors and measure stellar mass of individual galaxies. We use template-fitting photom…
CLASH: Precise New Constraints on the Mass Profile of the Galaxy Cluster A2261
Donahue, Megan; Broadhurst, Tom; Maoz, Dan +43 more
We precisely constrain the inner mass profile of A2261 (z = 0.225) for the first time and determine that this cluster is not "overconcentrated" as found previously, implying a formation time in agreement with ΛCDM expectations. These results are based on multiple strong-lensing analyses of new 16-band Hubble Space Telescope imaging obtained as par…
Solar Magnetic Field Reversals and the Role of Dynamo Families
Hoeksema, J. T.; Brun, A. S.; DeRosa, M. L.
The variable magnetic field of the solar photosphere exhibits periodic reversals as a result of dynamo activity occurring within the solar interior. We decompose the surface field as observed by both the Wilcox Solar Observatory and the Michelson Doppler Imager into its harmonic constituents, and present the time evolution of the mode coefficients…