Search Publications
Near-Ultraviolet Spectra of Flares on YZ CMi
Hawley, Suzanne L.; Valenti, Jeff A.; Walkowicz, Lucianne M. +1 more
Near-ultraviolet spectroscopic data obtained with the Hubble Space Telescope STIS (Space Telescope Imaging Spectrograph) instrument on the dMe flare star YZ Canis Minoris (YZ CMi) were analyzed. Flare and quiet intervals were identified from the broadband near-UV light curve, and the spectrum of each flare was separately extracted. Mg II and Fe II…
Active Region Loops: Temperature Measurements as a Function of Time from Joint TRACE and SOHO CDS Observations
Mason, H. E.; Del Zanna, G.; Schmelz, J. T. +3 more
In this paper, we aim to quantitatively investigate the structure and time variation of quiescent active region loop structures. We coordinated a joint program of observations (JOP 146) using TRACE, to obtain high-cadence EUV images, and SOHO CDS, to obtain spectroscopic data. Loop intensities are used to determine temperature as a function of tim…
Io’s Atmospheric Response to Eclipse: UV Aurorae Observations
Stern, S. A.; Saur, J.; Strobel, D. F. +18 more
The New Horizons (NH) spacecraft observed Io’s aurora in eclipse on four occasions during spring 2007. NH Alice ultraviolet spectroscopy and concurrent Hubble Space Telescope ultraviolet imaging in eclipse investigate the relative contribution of volcanoes to Io’s atmosphere and its interaction with Jupiter’s magnetosphere. Auroral brightness and …
The Sizes of Galaxy Halos in Galaxy Cluster Abell 1689
Pannella, M.; Seitz, S.; Halkola, A.
The multiple images observed in the galaxy cluster Abell 1689 provide strong constraints not only on the mass distribution of the cluster, but also on the ensemble properties of the cluster galaxies. Using parametric strong-lensing models for the cluster, and by assuming well-motivated scaling laws between the truncation radius s and the velocity …
The Ribbon-like Hard X-Ray Emission in a Sigmoidal Solar Active Region
Liu, Chang; Wang, Haimin; Gary, Dale E. +1 more
Solar flare emissions at Hα and EUV/UV wavelengths often appear in the form of two ribbons, and this has been regarded as evidence of a typical configuration of solar magnetic reconnection. However, such a ribbon structure has rarely been observed in hard X-rays (HXRs), although it is expected. We report a ribbon-like HXR source observed with the …
The Outer Solar Atmosphere during the Maunder Minimum: A Stellar Perspective
Judge, Philip G.; Saar, Steven H.
By comparing solar data with data of ``flat activity'' stars at UV and soft X-ray wavelengths, we estimate solar chromospheric, transition region, and coronal emission as it might have existed during the Maunder minimum (1645-1715), the most recent of several episodes of persistently weak sunspot activity. Several flat activity stars from the Moun…
Properties of Solar Polar Coronal Plumes Constrained by Ultraviolet Coronagraph Spectrometer Data
Solanki, S. K.; Raouafi, N. -E.; Harvey, J. W.
We investigate the plasma dynamics (outflow speed and turbulence) inside polar plumes. We compare line profiles (mainly of O VI) observed by the Ultraviolet Coronagraph Spectrometer (UVCS) instrument on SOHO at the minimum of solar cycle 22-23 with model calculations. We consider Maxwellian velocity distributions with different widths in plume and…
The spatial clustering of mid-IR selected star forming galaxies at z ~ 1 in the GOODS fields
Daddi, E.; Elbaz, D.; Stern, D. +6 more
We present the first spatial clustering measurements of z∼1, 24 µm-selected, star forming galaxies in the Great Observatories Origins Deep Survey (GOODS). The sample under investigation includes 495 objects in GOODS-South and 811 objects in GOODS-North selected down to flux densities of f24>20 µJy and z_AB<23.5 mag, fo…
On the Anomalous Temperature Distribution of the Intergalactic Medium in the NGC 3411 Group of Galaxies
O'Sullivan, E.; Ponman, T. J.; Vrtilek, J. M. +1 more
We present XMM-Newton, Chandra, and VLA observations of the USGC S152 group and its central elliptical NGC 3411. Imaging of the group X-ray halo suggests that it is relaxed with little apparent structure. We investigate the temperature and metal abundance structure of the group halo and find that while the abundance distribution is fairly typical,…
General Relativistic Flux Modulations from Disk Instabilities in Sagittarius A*
Melia, Fulvio; Goldwurm, Andrea; Bélanger, Guillaume +2 more
Near-IR and X-ray flares have been detected from the supermassive black hole Sgr A* at the center of our Galaxy with a (quasi-)period of ~17-20 minutes, suggesting an emission region only a few Schwarzschild radii above the event horizon. The latest X-ray flare, detected with XMM-Newton, is notable for its detailed light curve, yielding not only t…