Search Publications
DS Andromedae: A Detached Eclipsing Double-lined Spectroscopic Binary in the Galactic Cluster NGC 752
Frandsen, S.; Milone, E. F.; Schiller, S. J. +1 more
The Wilson-Devinney program has been used to analyze well-calibrated photometric and new radial velocity data to determine the properties and distance of DS Andromedae, a 1.01 day period, double-lined, totally eclipsing binary system of early-F spectral type and a likely member of the intermediate-age open cluster NGC 752. The determinations of ma…
On the Properties of the Galactic Dust Layer within 700 pc of the Sun
Gontcharov, G. A.
We compare the spatial stellar color variations with our three-dimensional analytical model of the spatial dust distribution to refine the properties of the dust layer in Galactic solar neighborhoods. We use a complete sample of 93 992 clump giants with a small admixture of branch giants from the Gaia DR2 catalogue in a spatial cylinder with a rad…
Poisson vs. Gaussian statistics for sparse X-ray data: Application to the soft X-ray spectrometer
Eckart, Megan E.; Kelley, Richard L.; Kilbourne, Caroline A. +8 more
Reliable results when fitting X-ray data require proper consideration of the statistics involved. We probe the impact of Gaussian versus Poisson statistics at low count levels using both the standard χ2 method and maximum likelihood based on Poisson (C) statistics. The difference is studied and quantified through simulated spectra with …
Radio observations of evaporating objects in the Cygnus OB2 region
del Palacio, S.; Fernández-López, M.; Ishwara-Chandra, C. H. +2 more
We present observations of the Cygnus OB2 region obtained with the Giant Metrewave Radio Telescope (GMRT) at frequencies of 325 and 610 MHz. In this contribution we focus on the study of proplyd-like objects (also known as free-floating evaporating gas globules or frEGGs) that typically show an extended cometary morphology. We identify eight objec…
Strongly magnetic Ap stars in the Gaia DR2 Hertzsprung-Russell diagram . I. Selecting the most reliable astrometric and photometric data
Hubrig, S.; Chojnowski, S. Drew; Scholz, R. -D.
Context. Knowing the distribution of strongly magnetic Ap stars in the Hertzsprung-Russell diagram (HRD) allows us to study the evolution of their magnetic fields across the main sequence (MS). With a newly extended Ap star sample from APOGEE and available Gaia DR2 data, we can now critically review the results of previous studies based on HIPPARC…
Optical counterparts of an ultraluminous X-Ray Source X-1 in NGC 2500
Akyuz, A.; Aksaker, N.; Avdan, S. +1 more
We present the results of a search for optical counterparts of ultraluminous X-ray source (ULX) X-1 in the nearby galaxy NGC 2500 by using archival images taken with the Hubble Space Telescope Wide Field Camera (WFC3)/UVIS. We identified four optical sources as possible counterparts within the 2σ error radius of 0^' ' }.3 in the images.…
Distance to the nearby dwarf galaxy [TT2009] 25 in the NGC 891 group using the tip of the red giant branch
Müller, Oliver; Ibata, Rodrigo; Rejkuba, Marina +1 more
Dwarf galaxies are key objects for small-scale cosmological tests like the abundance problems or the planes-of-satellites problem. A crucial task is therefore to get accurate information for as many nearby dwarf galaxies as possible. Using extremely deep, ground-based V and i-band Subaru Suprime Cam photometry with a completeness of i = 27 mag, we…
Photometric observations of the W UMa stars CSS J113505.5+332031, ASAS J142124+1813.1 and HR Boo
Michel, R.; Kjurkchieva, D.
Multicolor photometric observations of the W UMa binaries CSS J113505.5+332031, ASAS J142124+1813.1 and HR Boo are presented. They led to improvement of the orbital periods of CSS J113505.5+332031 and HR Boo. The light curve solutions revealed that all the targets are overcontact binaries with moderate fill-out factors whose components are of G an…
The Next Generation Fornax Survey (NGFS). V. Discovery of a Dwarf-Dwarf Galaxy Pair at z = 0.30 and Its Characterization Using Deep VLT/MUSE Observations
Grebel, Eva K.; Mieske, Steffen; Rong, Yu +11 more
We report the detection of a pair of dwarf galaxies at z = 0.30 that may be in the early stages of an interaction. Both galaxies have stellar masses of <109 M ⊙ and display a projected separation of ∼29 kpc and a physical separation of ∼240 kpc. Evidence of ongoing star formation has been found in both galaxies, with neith…
A Magellanic origin for the Virgo sub-structure
Belokurov, V.; Iorio, G.; Erkal, D. +1 more
The Milky Way halo has been mapped out in recent work using a sample of RR Lyrae stars drawn from a cross-match of Gaia with 2MASS. We investigate the significant residual in this map which we constrain to lie at Galactocentric radii 12 < R < 27 kpc and extend over 2600 deg2 of the sky. A counterpart of this structure exists in bo…