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XMM-Newton observations of AM CVn binaries: V396 Hya and SDSS J1240-01
Groot, P. J.; Ramsay, G.; Hakala, P. +3 more
We present the results of XMM-Newton observations of two AM CVn systems - V396 Hya and SDSS J1240-01. Both systems are detected in X-rays and in the UV: neither shows coherent variability in their light curves. We compare the rms variability of the X-ray and UV power spectra of these sources with other AM CVn systems. Apart from ES Cet, AM CVn sou…
Hubble Space Telescope Observations of Star Clusters in M101
Barmby, P.; Kuntz, K. D.; Huchra, J. P. +1 more
Hubble Space Telescope Advanced Camera for Surveys (ACS) images are used to identify and study star cluster candidates in the nearby spiral galaxy M101. About 3000 round, slightly resolved cluster candidates are identified in 10 ACS pointings covering an area of 106 arcmin2. The cluster candidates' color and size distributions are consi…
Ages of rampart craters in equatorial regions on Mars: Implications for the past and present distribution of ground ice
Jaumann, R.; Neukum, G.; Hauber, E. +3 more
We are testing the idea of Squyres et al. (1992) that rampart craters on Mars may have formed over a significant time period and therefore the onset diameter (minimum diameter of a rampart crater) only reflects the ground ice depth at a given time. We measured crater size frequencies on the layered ejecta of rampart craters in three equatorial reg…
Analysis of IUE spectra of helium-rich white dwarf stars
Kepler, S. O.; Handler, G.; Koester, D. +1 more
We studied the class of DB white dwarf stars, using re-calibrated UV spectra for thirty four DBs obtained with the IUE satellite. By comparing the observed energy distributions with model atmospheres, we simultaneously determine spectroscopic distances (d), effective temperature (Teff), and surface gravities (log g). Using parallax meas…
Prospects for dark energy evolution: a frequentist multi-probe approach
Yvon, D.; Tao, C.; Tilquin, A. +4 more
A major quest in cosmology is to understand the nature of dark energy. It is now well known that the use of several cosmological probes is required to break the underlying degeneracies on cosmological parameters. In this paper, we present a method based on a frequentist approach that combines probes without any prior constraints. As one applicatio…
The XMM-Newton view of GRS 1915+105
Belloni, T.; Ponti, G.; Matt, G. +3 more
Two XMM-Newton observations of the black-hole binary GRS 1915+105 were triggered in 2004 (April 17 and 21), during a long "plateau" state of the source. We analyzed the data collected with EPIC-pn in timing and burst modes, respectively. Reflection Grating Spectrometers were used only on April 21st. The source 2-10 keV flux is 0.6 (unabsorbed: 0.9…
The XMM-Newton view of the Crab
Freyberg, M. J.; Wilms, J.; Kendziorra, E. +7 more
Aims.We discuss the current X-ray view of the Crab Nebula and Pulsar, summarising our analysis of observations of the source with the EPIC-pn camera on board the XMM-Newton observatory. Different modes of EPIC-pn were combined in order to yield a complete scenario of the spectral properties of the Crab resolved in space and time (pulse phase). In …
UIR bands in the ISO SWS spectrum of the carbon star TU Tauri
Hony, S.; Tielens, A. G. G. M.; Boersma, C.
Polycyclic Aromatic Hydrocarbon (PAH) molecules are thought to form in the ejecta of carbon-rich Asymptotic Giant Branch (AGB) stars. Fifty ISO SWS spectra of warm carbon-rich AGB stars have been investigated for the Unidentified IR (UIR) emission due to fluorescence by PAH molecules. In this sample the binary star TU Tau, which has a blue compani…
Near-infrared imaging polarimetry of dusty young stars
Barlow, M. J.; Gledhill, T. M.; Lowe, K. T. E. +1 more
We have carried out JHK polarimetric observations of 11 dusty young stars, by using the polarimeter module IRPOL2 with the near-infrared camera UIST on the 3.8-m United Kingdom Infrared Telescope (UKIRT). Our sample targeted systems for which UKIRT-resolvable discs had been predicted by model fits to their spectral energy distributions. Our observ…
Photometric Identification of Type Ia Supernovae at Moderate Redshift
Johnson, Benjamin D.; Crotts, Arlin P. S.
Large photometric surveys with the aim of identifying many Type Ia supernovae (SNe) at moderate redshift are challenged in separating these SNe from other SN types. We are motivated to identify Type Ia SNe based only on broadband photometric information, since spectroscopic determination of the SN type, the traditional method, requires significant…