Search Publications
Significant X-ray Line Emission in the 5-6 keV Band of NGC 4051
Turner, T. J.; Kraemer, S. B.; Crenshaw, D. M. +4 more
A Suzaku X-ray observation of NGC 4051 taken during 2005 November reveals line emission at 5.44 keV in the rest frame of the galaxy which does not have an obvious origin in known rest-frame atomic transitions. The improvement to the fit statistic when this line is accounted for establishes its reality at >99.9% confidence: we have also verified…
Ultraluminous X-ray Sources in Arp 147
Rappaport, S.; Levine, A.; Pooley, D. +1 more
The Chandra X-Ray Observatory was used to image the collisional ring galaxy Arp 147 for 42 ks. We detect nine X-ray sources with luminosities in the range of (1.4-7) × 1039 erg s-1 (assuming that the sources emit isotropically) in or near the blue knots of star formation associated with the ring. A source with an X-ray lumino…
Mid-infrared diagnostics of metal-rich HII regions from VLT and Spitzer spectroscopy of young massive stars in W31
Crowther, P. A.; Morris, P. W.; Conti, P. S. +4 more
We present near-infrared Very Large Telescope/Infrared Spectrograph and Array Camera and mid-infrared (mid-IR) Spitzer/Infrared Spectrograph spectroscopy of the young massive cluster in the W31 star-forming region. H-band spectroscopy provides refined classifications for four cluster member O stars with respect to Blum et al. In addition, photosph…
X-Ray and Optical Study of Low Core Density Globular Clusters NGC6144 and E3
Anderson, Scott F.; Kong, Albert K. H.; Verbunt, Frank +4 more
We report on the Chandra X-ray Observatory and Hubble Space Telescope (HST) observations of two low core-density globular clusters, NGC6144 and E3. By comparing the number of X-ray sources inside the half-mass radius to those outside, we found six X-ray sources within the half-mass radius of NGC6144, of which four are expected to be background sou…
Venusian bow shock as seen by the ASPERA-4 ion instrument on Venus Express
Coates, A. J.; Kallio, E.; Schmidt, W. +40 more
The Analyzer of Space Plasmas and Energetic Atoms (ASPERA-4) instrument on Venus Express is used to determine bow shock position at Venus using ion data alone, using data recorded during a solar minimum from the Ion Mass Analyzer (IMA) which is part of the ASPERA-4 package. Previous models constructed from solar minimum data using Venus Express, P…
A variable jet model for the Hα emission of HH 444
Raga, A. C.; Riera, A.; González-Gómez, D. I.
Context. HH 444 is one of the first Herbig-Haro (HH) jets discovered within a photoionized region.
Aims: We re-analyze the Hα and red [S II] HST images of HH 444, and calculate the width of the jet as a function of distance from the source. We compare the Hα image with predictions from variable ejection velocity jet models.
Methods: The …
Chromospheric Signatures of Small-scale Flux Emergence as Observed with New Solar Telescope and Hinode Instruments
Chae, J.; Goode, P. R.; Abramenko, V. I. +4 more
With the ever-increasing influx of high-resolution images of the solar surface obtained at a multitude of wavelengths, various processes occurring at small spatial scales have become a greater focus of our attention. Complex small-scale magnetic fields have been reported that appear to have enough stored energy to heat the chromosphere. While sign…
Scattered Hα emission from a large translucent cloud G294-24
Juvela, M.; Lehtinen, K.; Mattila, K.
Aims: We study an undocumented large translucent cloud, detected by means of its enhanced radiation in the SHASSA (Southern H-Alpha Sky Survey Atlas) survey. We consider whether its excess surface brightness can be explained by light scattered off the dust grains in the cloud, or whether emission from in situ ionized gas is required. In addit…
Angular diameter estimation of interferometric calibrators. Example of λ Gruis , calibrator for VLTI-AMBER
Cruzalèbes, P.; Jorissen, A.; Bonneau, D. +1 more
Context. Accurate long-baseline interferometric measurements require careful calibration with reference stars. Small calibrators with high angular diameter accuracy ensure the true visibility uncertainty to be dominated by the measurement errors.
Aims: We review some indirect methods for estimating angular diameter, using various types of inp…
Characteristics of Saturn’s FUV airglow from limb-viewing spectra obtained with Cassini-UVIS
Gérard, Jean-Claude; Stewart, Ian; Gustin, Jacques +1 more
This study reports the analysis of far ultraviolet (FUV) limb spectra of the airglow of Saturn in the 1150-1850 Å spectral window, obtained with the Ultraviolet Imaging Spectrograph (UVIS) onboard Cassini, spanning altitudes from -1200 to 4000 km. The FUV limb emission consists of three main contributions: (1) H Ly-α peaking at 1100 km with a brig…