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IR Com: Deeply Eclipsing Dwarf Nova Below the Period Gap -- A Twin of HT Cas?
We observed an X-ray selected, deeply eclipsing cataclysmic variable IRCom (= S 10932). We detected an outburst occurring on 1996 January 1.The light curve of the outburst closely resembled that of a normaloutburst of an SU UMa-type dwarf nova, rather than that of anintermediate polar. Time-resolved photometry during the outburst showedthat eclipses became systematically deeper and narrower as the outburstfaded. Full-orbit light curves in quiescence showed little evidence oforbital humps or asymmetry of the eclipses. In addition to the presenceof high-low transitions in quiescence, the overall behavior of theoutbursts and the characteristics of the eclipse profiles suggest thatIR Com can be best understood as a twin of HT Cas, a famous eclipsing SUUMa-type dwarf nova with a number of peculiarities.
| Fe/H, age and distance for the F-stars of an unbiased radial velocity sample at the north Galactic pole
New limits for the normalization of stellar populations of the solarneighborhood have been suggested by Sandage and Fouts (1987). Log T(e),M(V), Fe/H abundance ratio, age A, distance and color excess arepresented for 183 stars of Sandage and Fouts' unbiased radial velocitysample located near the north Galactic pole.
| U, V, W velocity components for the old disk using radial velocities of 1295 stars in the three cardinal Galactic directions
New radial velocities are presented for 1295 stars chosen at random nearthe three cardinal Galactic directions of l = 180 deg, b = 0; l = 90deg, b = 0 deg; and b = 90 deg, giving the distribution in U, V, and W,respectively, from the radial velocities alone. The measurements weremade with the coude spectrograph of the Mount Wilson 100 in. Hookerreflector. The purpose of the program is to set limits on the densitynormalization in the solar neighborhood of the old thin disk, the oldthick disk, and the halo. Many more high-velocity stars are present inthe unbiased sample than expected from previous estimates of thenormalization. The data suggest the density ratios in the solarneighborhood to be about 90 percent, 10 percent, and about 0.5 percentfor the thin disk, thick disk, and halo populations, respectively.
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