Search Publications
Newly Identified Star Clusters in NGC 6822, and the Age Distribution of Its Cluster System
Hodge, Paul; Krienke, Karl
From past ground-based imaging and our current Hubble Space Telescope images, we have identified 51 candidate open clusters in the dwarf irregular galaxy NGC 6822. Of these, 25 candidates are located on our HST images with standard wideband filters, 16 of which are securely identified as true clusters. Integrated photometry in B, V, and I for seve…
Computation of the Adiabatic Eigenmodes of Stars Using the Riccati Method
Takata, Masao; Löffler, Wolfgang
In stellar oscillation problems, it is often necessary to compute a large number of stellar eigenmodes with wildly varying radial orders and angular degrees. Conventionally the relaxation method is used for this purpose. This method is, however, fraught with several numerical issues, which make it cumbersome and tedious to write the corresponding …
Limits on I-Band Microvariability of the Galactic Bulge Mira Variables
McGowan, K. E.; Vestrand, W. T.; Woźniak, P. R.
We search for microvariability in a sample of 485 Mira variables with high-quality I-band light curves from the second-generation Optical Gravitational Lensing Experiment (OGLE-II). Rapid variations with amplitudes in the ~0.2-1.1 mag range lasting hours to days were discovered in Hipparcos data by de Laverny et al. Our search is primarily sensiti…
A Uniform Database of 2.2-16.5 µm Spectra from the ISOCAM CVF Spectrometer
Engelke, C. W.; Kraemer, Kathleen E.; Price, Stephan D.
We present all ISOCAM circular variable filter (CVF) spectra that cover more than one-third of the 2.2-16.5 µm spectral range of the instrument. The 364 spectra have been classified according to the classification system of Kraemer et al., as modified by Hodge et al. to account for the shorter wavelength range. Prior to classification, the s…
Martian northern polar cap: Layering and possible implications for radar sounding
Ilyushin, Yaroslaw A.
The propagation of electromagnetic waves in the northern polar ice sheet of Mars is considered. It is shown that the dispersion and attenuation of radio waves in the polar sheet are regulated by two groups of factors: the physical and chemical composition of the ice, and the geometrical parameters of the layered structure of polar sheet. Both anal…
Fundamental parameters and evolutionary state of the Herbig Ae star candidate HD 35929
Miroshnichenko, A. S.; Bjorkman, K. S.; Gray, R. O. +2 more
HD 35929 is a pre-main-sequence Herbig Ae star candidate that exhibits emission in the Hα line and a weak IR excess. Although its luminosity type was estimated as IV from low-resolution spectroscopy, the insignificant HIPPARCOS parallax (0.88±0.93 mas) contradicted the low luminosity. To resolve this discrepancy, we took 3 high-resolution optical …
Stars of Extragalactic Origin in the Solar Neighborhood
Borkova, T. V.; Marsakov, V. A.
For 77 main-sequence F-G stars in the solar neighborhood with published iron, magnesium, and europium abundances determined from high-dispersion spectra and with the ages estimated from theoretical isochrones, we calculated the spatial velocities using Hipparcos data and the Galactic orbital elements. A comparison with the orbital elements of the …
Photoionization model analysis of the planetary nebula Hu1-2
Pottasch, S. R.; Feibelman, W. A.; Hyung, S.
We have obtained high resolution optical spectra of the planetary nebula
A Hubble Space Telescope STIS Observation of VW Hydri at the Exact Far-Ultraviolet Onset of an Outburst
Szkody, Paula; Sion, Edward M.; Gänsicke, Boris T. +1 more
We present an analysis of Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph data of VW Hyi that we acquired 14 days after a superoutburst. At the time of our observation, the system appears to be going into outburst with the longest wavelengths increasing in flux by a factor of 5 while the shortest wavelengths increase by only a fa…
The Luminous Erupting Dwarf Nova CV 1 in the Dense Globular Cluster M15
Zurek, David R.; Hinkley, Sasha; Bond, Howard E. +2 more
Despite decades-old predictions of the expected presence of dozens of cataclysmic variables in the cores of globular clusters, the number of irrefutable, outbursting candidates is still barely a handful. Using multiwavelength, multiepoch Hubble Space Telescope images, we have produced outburst and quiescence light curves for the recently discovere…