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Metal Abundances and Kinematics of Bright Metal-poor Giants Selected from the LSE Survey: Implications for the Metal-weak Thick Disk
Beers, Timothy C.; von Hippel, Ted; Rossi, Silvia +5 more
We report medium-resolution (1-2 Å) spectroscopy and broadband (UBV) photometry for a sample of 39 bright stars (the majority of which are likely to be giants) selected as metal-deficient candidates from an objective-prism survey concentrating on Galactic latitudes below |b|=30°, the Luminous Stars Extension (LSE) survey of Drilling & Bergeron…
Deep Hubble Space Telescope Imaging of Sextans A. I. The Spatially Resolved Recent Star Formation History
Skillman, Evan D.; Dolphin, Andrew; Cole, Andrew A. +5 more
We have measured stellar photometry from deep Cycle 7 Hubble Space Telescope/WFPC2 imaging of the dwarf irregular galaxy Sextans A. The imaging was taken in three filters: F555W (V; eight orbits), F814W (I; 16 orbits), and F656N (Hα one orbit). Combining these data with Cycle 5 WFPC2 observations provides nearly complete coverage of the optically …
Radial Velocity Studies of Close Binary Stars. VI.
Rucinski, Slavek M.; Capobianco, Christopher C.; Lu, Wenxian +5 more
Radial velocity measurements and sine-curve fits to the orbital velocity variations are presented for the sixth set of 10 close binary systems: SV Cam, EE Cet, KR Com, V410 Cyg, GM Dra, V972 Her, ET Leo, FS Leo, V2388 Oph, and II UMa. All systems except FS Leo are double-lined spectroscopic binaries. The type of FS Leo is unknown, while SV Cam is …
The Distance Scale for Classical Cepheid Variables
Turner, David G.; Burke, James F.
New radii, derived from a modified version of the Baade-Wesselink (BW) method that is tied to published KHG narrowband spectrophotometry, are presented for 13 bright Cepheids. The data yield a best-fitting period-radius relation given by log<R/Rsolar>=1.071(+/-0.025)+0.747(+/- 0.028)logP0. In combination with other high…
Hubble Space Telescope Observations of Proper Motions in Herbig-Haro Objects 1 and 2
Hartigan, Patrick; Bally, John; Morse, Jon +3 more
Hubble Space Telescope observations obtained in 1994 and 1997 are used to measure proper motions in the HH 1/2 protostellar outflow in Orion. Since the HH 1/2 system lies within 10° of the plane of the sky, proper motions provide accurate measures of true space velocities. Comparison of the 1994 and 1997 images reveals a variety of changes such as…
Structural Parameters for Globular Clusters in NGC 5128
Holland, Stephen T.; Harris, William E.; Harris, Gretchen L. H. +1 more
We present new imaging measurements of 27 individual globular clusters in the halo of the nearby elliptical galaxy NGC 5128, obtained with the Hubble Space Telescope Imaging Spectrograph and Wide Field Planetary Camera 2. We use the cluster light profiles to determine their structural parameters (core and half-light radii, central concentration, a…
What Fraction of the Young Clusters in the Antennae Galaxies Are ``Missing''?
Whitmore, Bradley C.; Zhang, Qing
A reexamination of the correspondence between 6 cm radio continuum sources and young star clusters in the Antennae galaxies indicates that ~85% of the strong thermal sources have optical counterparts, once the optical image is shifted 1.2" to the southwest. A sample of 37 radio-optical matches are studied in detail, showing correlations between ra…
The Dwarf Spheroidal Companions to M31: Variable Stars in Andromeda VI
Pritzl, Barton J.; Armandroff, Taft E.; Da Costa, Gary S. +1 more
We have surveyed Andromeda VI, a dwarf spheroidal galaxy companion to M31, for variable stars by using F450W and F555W observations obtained with the Hubble Space Telescope. A total of 118 variables were found, including 111 RR Lyrae stars, six anomalous Cepheids, and one variable that we were unable to classify. We find that the Andromeda VI anom…
Determination of the Distance to M33 Based on the Tip of the Red Giant Branch and the Red Clump
Sarajedini, Ata; Lee, Myung Gyoon; Geisler, Doug +2 more
We have determined the distance to M33 using the tip of the red giant branch (TRGB) and the red clump (RC), from the VI photometry of stars in 10 regions of M33 based on HST/WFPC2 images. The regions used in this study are located at R=2.6‧-17.8‧ from the center of M33. The distance modulus to M33 obtained in this study, for an adopted foreground …
The Microjansky Sky at 8.4 GHz
Fomalont, E. B.; Windhorst, R. A.; Richards, E. A. +2 more
We present the results from two deep radio integrations at 8.4 GHz using the Very Large Array. One of the fields, at 13h, +43° (SA 13 field), has an rms noise level of 1.49 µJy and is the deepest radio image yet made. Thirty-four sources in a complete sample were detected above 7.5 µJy, and 25 are optically identified to a l…