Search Publications
Magnetic Helicity Spectrum of Solar Wind Fluctuations as a Function of the Angle with Respect to the Local Mean Magnetic Field
Podesta, J. J.; Gary, S. P.
Magnetic field data acquired by the Ulysses spacecraft in high-speed streams over the poles of the Sun are used to investigate the normalized magnetic helicity spectrum σ m as a function of the angle θ between the local mean magnetic field and the flow direction of the solar wind. This spectrum provides important information about the …
Ice and Dust in the Quiescent Medium of Isolated Dense Cores
van Dishoeck, E. F.; Blake, G. A.; Decin, L. +6 more
The relation between ices in the envelopes and disks surrounding young stellar objects (YSOs) and those in the quiescent interstellar medium (ISM) is investigated. For a sample of 31 stars behind isolated dense cores, ground-based and Spitzer spectra and photometry in the 1-25 µm wavelength range are combined. The baseline for the broad and …
A Massive Progenitor of the Luminous Type IIn Supernova 2010jl
Van Dyk, Schuyler D.; Filippenko, Alexei V.; Smith, Nathan +6 more
The bright, nearby, recently discovered supernova (SN) 2010jl is a luminous Type IIn SN. Here, we report archival Hubble Space Telescope (HST) observations of its host galaxy UGC 5189A taken roughly 10 yr prior to explosion, as well as early-time optical spectra of the SN. The HST images reveal a luminous, blue point source at the position of the …
Cluster Mass Profiles from a Bayesian Analysis of Weak-lensing Distortion and Magnification Measurements: Applications to Subaru Data
Broadhurst, Tom; Zitrin, Adi; Umetsu, Keiichi +2 more
We directly construct model-independent mass profiles of galaxy clusters from combined weak-lensing distortion and magnification measurements within a Bayesian statistical framework, which allows for a full parameter-space extraction of the underlying signal. This method applies to the full range of radius outside the Einstein radius, and recovers…
The Progenitor of Supernova 2011dh/PTF11eon in Messier 51
Van Dyk, Schuyler D.; Filippenko, Alexei V.; Cenko, S. Bradley +12 more
We have identified a luminous star at the position of supernova (SN) 2011dh/PTF11eon, in pre-SN archival, multi-band images of the nearby, nearly face-on galaxy Messier 51 (M51) obtained by the Hubble Space Telescope with the Advanced Camera for Surveys. This identification has been confirmed, to the highest available astrometric precision, using …
Metallicity Gradient of a Lensed Face-on Spiral Galaxy at Redshift 1.49
Swinbank, A. M.; Richard, J.; Yuan, T. -T. +2 more
We present the first metallicity gradient measurement for a grand-design face-on spiral galaxy at z ~ 1.5. This galaxy has been magnified by a factor of 22× by a massive, X-ray luminous galaxy cluster MACS J1149.5+2223 at z = 0.544. Using the Laser Guide Star Adaptive Optics aided integral field spectrograph OSIRIS on KECK II, we target the Hα emi…
The SL2S Galaxy-scale Lens Sample. II. Cosmic Evolution of Dark and Luminous Mass in Early-type Galaxies
Treu, Tommaso; Gavazzi, Raphaël; Marshall, Philip J. +3 more
We present a joint gravitational lensing and stellar-dynamical analysis of 11 early-type galaxies (median deflector redshift z d = 0.5) from Strong Lenses in the Legacy Survey (SL2S). Using newly measured redshifts and stellar velocity dispersions from Keck spectroscopy with lens models from Paper I, we derive the total mass-density slo…
Heating the Hot Atmospheres of Galaxy Groups and Clusters with Cavities: The Relationship between Jet Power and Low-frequency Radio Emission
Giacintucci, S.; O'Sullivan, E.; Ponman, T. J. +4 more
We present scaling relations between jet power and radio power measured using the Giant Metrewave Radio Telescope (GMRT), Chandra, and XMM-Newton, for a sample of nine galaxy groups combined with the Bîrzan et al. sample of clusters. Cavity power is used as a proxy for mechanical jet power. Radio power is measured at 235 MHz and 1.4 GHz, and the i…
First Evidence of Coexisting EIT Wave and Coronal Moreton Wave from SDO/AIA Observations
Chen, P. F.; Wu, Y.
"EIT waves" are a globally propagating wavelike phenomenon. They were often interpreted as fast-mode magnetoacoustic waves in the corona, despite various discrepancies between the fast-mode wave model and observations. To reconcile these discrepancies, we suggested that "EIT waves" are the apparent propagation of the plasma compression due to succ…
The First Observation of a Rapidly Rotating Coronal Mass Ejection in the Middle Corona
Nieves-Chinchilla, T.; Stenborg, G.; Vourlidas, A. +1 more
In this Letter, we present the first direct detection of a rotating coronal mass ejection (CME) in the middle corona (5-15 R sun). The CME rotation rate is 60° day-1, which is the highest rate reported yet. The Earth-directed event was observed by the STEREO/SECCHI and SOHO/LASCO instruments. We are able to derive the three-d…