Search Publications
Discovery of the Pre-Main-Sequence Population of the Stellar Association LH 95 in the Large Magellanic Cloud with Hubble Space Telescope Advanced Camera for Surveys Observations
Henning, Thomas; Gouliermis, Dimitrios A.; Dolphin, Andrew E. +3 more
We report the discovery of an extraordinary number of pre-main-sequence (PMS) stars in the vicinity of the stellar association LH 95 in the Large Magellanic Cloud (LMC). Using the Advanced Camera for Surveys on board the Hubble Space Telescope in wide-field mode, we obtained deep high-resolution imaging of the main body of the association and of a…
Doppler Velocities Measured in Coronal Emission Lines from a Bright Point Observed with the EUNIS Sounding Rocket
Brosius, Jeffrey W.; Thomas, Roger J.; Rabin, Douglas M.
Spectroscopic measurements of a coronal bright point obtained with the Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS) sounding rocket instrument on 2006 April 12 show both upflows and downflows in all five of the best observed emission lines. Relative velocities on opposite sides of the feature were found to be +/-15 km s-1 i…
Can Chandra Resolve the Remaining Cosmic X-Ray Background?
Hickox, Ryan C.; Markevitch, Maxim
The deepest extragalactic X-ray observation, the 2 Ms Chandra Deep Field North (CDF-N), resolves ~80% of the total extragalactic cosmic X-ray background (CXB) in the 1-2 keV band. Recent work has shown that 70% of the remaining CXB flux is associated with sources detected by the Hubble Space Telescope (HST). This paper uses the existing CDF-N data…
Plasma Outflows in Coronal Streamers
Noci, Giancarlo; Gavryuseva, Elena
In this Letter we show that it is possible to determine slow velocities (~20 km s-1) in the extended solar corona by means of the ratio of the resonance doublet of O VI. We apply this technique to a quiescent streamer at solar minimum, observed by the Ultraviolet Coronagraph Spectrometer (UVCS) for 4 consecutive days, and determine the …
Coronal Diagnostic Spectrometer Observations of Isothermal and Multithermal Coronal Loops
Mason, H. E.; Del Zanna, G.; Schmelz, J. T. +3 more
A data set obtained on 2003 January 17 with the Coronal Diagnostic Spectrometer (CDS) shows two loops sitting side by side on the solar disk. These loops are oriented along the CDS slit, so all pixels in each loop were observed simultaneously. So, although the instrument has a relatively slow time cadence, changes as a function of time that may oc…
Synthetic Mid-UV Spectroscopic Indices of Stars
Chavez, M.; Buzzoni, A.; Morossi, C. +4 more
Using the UVBLUE library of synthetic stellar spectra we have computed a set of mid-UV line and continuum spectroscopic indices. We explore their behavior in terms of the leading stellar parameters (Teff, logg). The overall result is that synthetic indices follow the general trends depicted by those computed from empirical databases. Se…
Detection of Surface Brightness Fluctuations in Elliptical Galaxies Imaged with the Advanced Camera for Surveys: B- and I-Band Measurements
Blakeslee, John P.; Cantiello, Michele; Raimondo, Gabriella +2 more
Taking advantage of the exceptional capabilities of the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope (HST), we derive surface brightness fluctuation (SBF) measurements in the B and I bands from images of six elliptical galaxies with 1500<=cz<=3500. Given the low signal-to-noise ratio (S/N) of the SBF signal in the bl…
Searching High-Redshift Large-Scale Structures: Photometry of Four Fields around Quasar Pairs at z ~ 1
Cypriano, E. S.; West, M.; Santos, W. A. +3 more
We have studied the photometric properties of four fields around the high-redshift quasar pairs QP 1310+0007, QP 1355-0032, QP 0110-0219, and QP 0114-3140 at z~1 with the aim of identifying large-scale structures (galaxy clusters or groups) around them. This sample was observed with the Gemini Multi-Object Spectograph (GMOS) at the Gemini North an…
Synchrotron Radio Emission from a Fast Halo Coronal Mass Ejection
Bastian, T. S.
An interplanetary (IP) type II-like radio burst is analyzed. It occurred on 2003 June 17-18 in association with a fast halo coronal mass ejection (CME), an M6.8 soft-X-ray (SXR) flare, and it produced a solar proton event. Unlike coronal type II bursts and the majority of IP type II radio emissions, the IP type-II-like event associated with the fa…
Probing Unification with Chandra HETGS and XMM-Newton EPIC and RGS Spectroscopy of the Narrow Emission Line Galaxy NGC 2110
Lee, Julia C.; Weaver, Kimberly A.; Marshall, Herman L. +2 more
We present results from Chandra HETGS (250 ks over two epochs) and XMM-Newton EPIC and RGS (60 ks) observations of NGC 2110, which has been historically classified as a narrow emission line galaxy. Our results support the interpretation that the source is a Seyfert 2 viewed through a patchy absorber. The nuclear X-ray spectrum of the source is bes…