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The extended structure of the remote cluster B514 in M 31. Detection of extra-tidal stars
Bellazzini, M.; Galleti, S.; Federici, L. +3 more
Aims:We present a study of the density profile of the remote M 31 globular cluster B514, obtained from HST/ACS observations.
Methods: By coupling analysis of the distribution of the integrated light with star counts, we are able to reliably follow the profile of the cluster out to r ~ 35 arcsec, corresponding to ≃130 pc. The profile is well-fi…
Separation of the visible and dark matter in the Einstein ring LBGJ213512.73-010143
Smail, Ian; Swinbank, A. M.; Edge, A. C. +2 more
We model the mass distribution in the recently discovered Einstein ring LBGJ213512.73-010143 (the `Cosmic Eye') using archival Hubble Space Telescope imaging. We reconstruct the mass density profile of the z = 0.73 lens and the surface brightness distribution of the z = 3.07 source and find that the observed ring is best fitted with a dual-compone…
BVI Photometry and the Luminosity Functions of the Globular Cluster M92
Sarajedini, Ata; Chaboyer, Brian; Paust, Nathaniel E. Q.
We present new BVI ground-based photometry and VI space-based photometry for the globular cluster M92 (NGC 6341) and examine luminosity functions in B, V, and I containing over 50,000 stars ranging from the tip of the red giant branch to several magnitudes below the main-sequence turnoff. Once corrected for completeness, the observed luminosity fu…
Solar Oscillation Frequency Changes on Time Scales of Nine Days
Hill, F.; Jain, K.; Tripathy, S. C. +1 more
We establish that global solar p-mode frequencies can be measured with sufficient precision on time scales as short as nine days to detect activity-related shifts. Using ten years of GONG data, we report that mode-mass and error-weighted frequency shifts derived from nine days are significantly correlated with the strength of solar activity and ar…
First Detection of Phase-dependent Colliding Wind X-Ray Emission outside the Milky Way
Corcoran, Michael F.; Moffat, Anthony F. J.; Nazé, Yaël +1 more
After having reported the detection of X-rays emitted by the peculiar system HD 5980, we assess here the origin of this high-energy emission from additional X-ray observations obtained with XMM-Newton. This research provides the first detection of apparently periodic X-ray emission from hot gas produced by the collision of winds in an evolved mass…
The structure of the jet in 3C 15 from multiband polarimetry
Birkinshaw, M.; Worrall, D. M.; Padgett, C. A. +2 more
We investigate the structure of the kpc-scale jet in the nearby (z = 0.073) radio galaxy 3C 15, using new optical Hubble Space Telescope (HST) ACS/F606W polarimetry together with archival multiband HST imaging, Chandra X-ray data and 8.4-GHz VLA radio polarimetry. The new data confirm that synchrotron radiation dominates in the optical. With match…
Three-dimensional reconstruction of the streamer belt and other large-scale structures of the solar corona. I. Method
Llebaria, A.; Lamy, P.; Vibert, D. +1 more
Context: The high spatial resolution, white-light images obtained by the LASCO coronagraphs provide a detailed record of the solar corona over almost a full solar cycle. Their analysis and interpretation poses a formidable challenge for ultimately retrieving the 3-dimensional distribution of electrons in the corona.
Aims: Our goal is to implem…
In search of an unbiased temperature estimator for statistically poor X-ray spectra
Molendi, S.; Leccardi, A.
Although commonly employed by X-ray astronomers, maximum likelihood estimators are known to be biased. In this paper we investigate the bias associated with the measure of the temperature from an X-ray thermal spectrum. We show that, in the case of low surface brightness regions, commonly adopted estimators, such as those based on χ2 an…
A Comparative Study of Optical and Ultraviolet Effective Temperatures for DA White Dwarfs from the IUE Archive
Bergeron, P.; Lajoie, C. -P.
We present a comparative study of effective temperatures determined from the hydrogen Balmer lines and from the UV energy distribution for 140 DA white dwarfs drawn from the International Ultraviolet Explorer (IUE) archive. Our results indicate that the optical and UV temperatures of the majority of stars below Teff~40,000 K and within …
A census of young stellar populations in the warm ULIRG PKS 1345+12
Tadhunter, C. N.; González Delgado, R. M.; Holt, J. +1 more
We present a detailed investigation of the young stellar populations (YSP) in the radio-loud ultraluminous infrared galaxy (ULIRG), PKS1345+12 (z = 0.12), based on high-resolution Hubble Space Telescope (HST) imaging and long-slit spectra taken with the William Herschel Telescope (WHT) at La Palma. While the images clearly show bright knots sugges…