Search Publications
A Study of Optical Observing Techniques for Extra-Galactic Supernova Remnants: Case of NGC300
Millar, W. C.; White, G. L.; Filipovic, M. D.
We present the results of a study of observational and identification techniques used for surveys and spectroscopy of candidate supernova remnants (SNRs) in the Sculptor Group galaxy NGC300. The goal of this study was to investigate the reliability of using [SII]/H_alpha > 0.4 in optical SNR surveys and spectra as an identifying feature of extr…
A WFC3 study of globular clusters in NGC 4150: an early-type minor merger
Mutchler, Max; Calzetti, Daniela; Whitmore, Bradley C. +8 more
We combine near-ultraviolet (NUV; 2250 Å) and optical (U, B, V, I) imaging from the Wide Field Camera 3 (WFC3), on-board the Hubble Space Telescope (HST), to study the globular cluster (GC) population in NGC 4150, a sub-L* (MB∼-18.48 mag) early-type minor-merger remnant in the Coma I cloud. We use broad-band NUV-optical photometry from …
The nature of the high Galactic latitude O-star HD 93521: new results from X-ray and optical spectroscopy
Morel, T.; Rauw, G.; Palate, M.
Context. Owing to its unusual location and its isolation, the nature of the high Galactic latitude O9.5 Vp object HD 93521 is still uncertain.
Aims: We have collected X-ray and optical observations to characterize the star and its surroundings.
Methods: X-ray images and spectra are analysed to search for traces of a recent star formation…
Signatures of Large-Scale Structure of Universe in X-Rays
Tugay, A. V.
A new sample of 4299 galaxies with X-ray emission was obtained in this work by cross-correlating 2XMM catalog of X-ray sources with HyperLeda database of galaxies. We analyzed distributions of optical and X-ray fluxes, redshifts and X-ray luminosities for this sample. Virgo and Coma galaxy clusters can be easily detected at redshift-space distribu…
NGC 3627: a galaxy-dwarf collision?
Bomans, D. J.; Weżgowiec, M.; Soida, M.
Context. Group galaxies very often show distinct signs of interaction with both companion galaxies and the intragroup medium. X-ray observations are particularly helpful because they provide information on the temperatures and the densities of the hot gas in galaxies and intergalactic space. This can put important constraints on the nature and tim…
Looking Deep into the Cat's Eye: Structure and Rotation in the Fast Wind of the PN Central Star of NGC 6543
Prinja, R. K.; Cantiello, M.; Massa, D. L.
We present HST/STIS time-series spectroscopy of the central star of the "Cat's Eye" planetary nebula NGC 6543. Intensive monitoring of the UV lines over a 5.8 hr period reveals well-defined details of large-scale structure in the fast wind, which are exploited to provide new constraints on the rotation rate of the central star. We derive character…
Microwave and radio emission of dusty star-forming galaxies: implication for the cosmic radio background
Lagache, G.; Ysard, N.
We use the most up-to-date cosmological evolution models of dusty star-forming galaxies and radio sources to compute the extragalactic number counts and the cosmic background from 408 MHz to 12 THz (or 24 µm). The evolution model of star-forming galaxies reproduces the recent constraints obtained by Spitzer, Herschel, and ground-based submm …
Early-type W UMa contact binary system: New data on V535 Ara
Özkardeş, B.; Erdem, A.
This paper presents the results of spectroscopic and photometric observations of the early-type W UMa system V535 Ara. New high-resolution spectra were taken at the Mt. John University Observatory in 2007. Radial velocities and spectroscopic orbital elements of the system were determined by applying KOREL spectral disentangling. The resulting orbi…
Suzaku X-ray spectral study of the Compton-thick Seyfert galaxy NGC 5135
Risaliti, Guido; Singh, Veeresh; Braito, Valentina +1 more
We present the 0.5-50 keV Suzaku broad-band X-ray spectral study of the Compton-thick active galactic nucleus (AGN) in NGC 5135. The Suzaku observation provides the first detection of NGC 5135 above 10 keV that allowed us, for the first time, to estimate the absorbing column density, the intrinsic X-ray luminosity, the strength of the reflection c…
Weak G-band stars on the H-R diagram: clues to the origin of the Li anomaly
Jasniewicz, G.; Parthasarathy, M.; Palacios, A. +1 more
Aims: Weak G-band (WGB) stars are a rare class of cool luminous stars that present a strong depletion in carbon, but also lithium abundance anomalies that have been little explored in the literature since the first discovery of these peculiar objects in the early 1950s. Here we focus on the Li-rich WGB stars and report on their evolutionary s…