Search Publications
Observation of Kink Instability During Small B5.0 Solar Flare on 2007 June 4
Srivastava, A. K.; Khodachenko, M. L.; Kumar, Pankaj +1 more
Using multi-wavelength observations of SOHO/MDI, SOT-Hinode/blue-continuum (4504 Å), G band (4305 Å), Ca II H (3968 Å), and TRACE 171 Å, we present the observational signature of a highly twisted magnetic loop in AR 10960 during the period 04:43 UT-04:52 UT on 2007 June 4. SOT-Hinode/blue-continuum (4504 Å) observations show that penumbral filamen…
Multiwavelength Observations of Small-scale Reconnection Events Triggered by Magnetic Flux Emergence in the Solar Atmosphere
Aulanier, G.; Guglielmino, S. L.; Bellot Rubio, L. R. +3 more
The interaction between emerging magnetic flux and the pre-existing ambient field has become a "hot" topic for both numerical simulations and high-resolution observations of the solar atmosphere. The appearance of brightenings and surges during episodes of flux emergence is believed to be a signature of magnetic reconnection processes. We present …
New Tests for Disruption Mechanisms of Star Clusters: The Large and Small Magellanic Clouds
Whitmore, Bradley C.; Fall, S. Michael; Chandar, Rupali
We compare the observed bivariate distribution of masses (M) and ages (τ) of star clusters in the Large Magellanic Cloud (LMC) with the predicted distributions g(M, τ) from three idealized models for the disruption of star clusters: (1) sudden mass-dependent disruption, (2) gradual mass-dependent disruption, and (3) gradual mass-independent disrup…
The ACS LCID Project. VI. The Star Formation History of The Tucana dSph and The Relative Ages of the Isolated dSph Galaxies
Dolphin, A. E.; Hidalgo, S. L.; Mayer, L. +10 more
We present a detailed study of the star formation history (SFH) of the Tucana dwarf spheroidal galaxy. High-quality, deep HST/ACS data, collected in the framework of the LCID project, allowed us to obtain the deepest color-magnitude diagram to date, reaching the old main-sequence turnoff (F814 ~ 29) with good photometric accuracy. Our analysis, ba…
Expansion Velocity of Ejecta in Tycho's Supernova Remnant Measured by Doppler Broadened X-ray Line Emission
Katsuda, Satoru; Kunieda, Hideyo; Makishima, Kazuo +10 more
We show that the expansion of ejecta in Tycho's supernova remnant (SNR) is consistent with a spherically symmetric shell, based on Suzaku measurements of the Doppler broadened X-ray emission lines. All of the strong Kα line emissions show broader widths at the center than at the rim, while the centroid energies are constant across the remnant (exc…
The Dust-scattering X-ray Rings of the Anomalous X-ray Pulsar 1E 1547.0-5408
Tiengo, A.; Götz, D.; Mereghetti, S. +14 more
On 2009 January 22 numerous strong bursts were detected from the anomalous X-ray pulsar 1E 1547.0-5408. Swift/XRT and XMM-Newton/EPIC observations carried out in the following two weeks led to the discovery of three X-ray rings centered on this source. The ring radii increased with time following the expansion law expected for a short impulse of X…
Three-dimensional Morphology of a Coronal Prominence Cavity
Seaton, D. B.; Schmieder, B.; de Toma, G. +16 more
We present a three-dimensional density model of coronal prominence cavities, and a morphological fit that has been tightly constrained by a uniquely well-observed cavity. Observations were obtained as part of an International Heliophysical Year campaign by instruments from a variety of space- and ground-based observatories, spanning wavelengths fr…
NGC 404: A Rejuvenated Lenticular Galaxy on a Merger-induced, Blueward Excursion Into the Green Valley
Madore, Barry F.; Rich, R. Michael; Gil de Paz, Armando +14 more
We have discovered recent star formation in the outermost portion ((1-4) × R 25) of the nearby lenticular (S0) galaxy NGC 404 using Galaxy Evolution Explorer UV imaging. FUV-bright sources are strongly concentrated within the galaxy's H I ring (formed by a merger event according to del Río et al.), even though the average gas density is…
Star Formation Signatures in Optically Quiescent Early-type Galaxies
Salim, Samir; Rich, R. Michael
In recent years, an argument has been made that a high fraction of early-type galaxies (ETGs) in the local universe experience low levels (lsim1 M sun yr-1) of star formation (SF) that causes strong excess in UV flux, yet leaves the optical colors red. Many of these studies were based on Galaxy Evolution Explorer imaging of S…
Direct Observational Evidence of Filament Material Within Interplanetary Coronal Mass Ejections
Lepri, S. T.; Zurbuchen, T. H.
Coronal mass ejections (CMEs) are explosive events that escape the Sun's corona carrying solar material and energy into the heliosphere. The classic picture of a CME observed in the corona presents a "three-part structure," including a bright front at the leading edge indicating dense plasma, a low-density cavity, the possible signature of an embe…