Keck Studies of M31's Stellar Halo

We present Keck 10-meter/LRIS spectra of candidate red giants in the halo of M31, located at a projected radius of R=19kpc on the minor axis. These spectroscopic targets have been selected using a combination of UBRI-based and morphological screening to eliminate background galaxies. Radial velocity measurements are used to separate M31 halo giants from foreground Milky Way dwarf stars, M31 disk stars, and residual background galaxies. The metallicity of each M31 halo giant is measured using standard photometric and spectroscopic techniques, the latter based on the strength of the CaII triplet. The various [Fe/H] estimates are in rough agreement with one another. The data reveal a large spread (>2dex) in [Fe/H] in M31's halo; there is no strong radial [Fe/H] gradient. LRIS and HIRES spectra are also presented for red giants in five dwarf spheroidal satellites of M31: AndI, AndIII, AndV, AndVI, and AndVII. There appears to be a significant metallicity spread in AndVI and possibly in AndI. The new radial velocity data on these outer dwarfs are used to constrain the total mass of M31: the best estimate is under 10^(12)Msun, somewhat less than the best estimate for the Milky Way.Comment: 12 pages, 7 figures, Proceedings of SPIE Conference: Discoveries and Research Prospects with 8-10 Meter Class Telescopes (Munich March 2000

Kinematics and Composition of the Galactic Bulge: Recent Progress

We present recent results from a Keck study of the composition of the Galactic bulge, as well as results from the bulge Bulge Radial Velocity Assay (BRAVA). Culminating a 10 year investigation, Fulbright, McWilliam, & Rich (2006, 2007) solved the problem of deriving the iron abundance in the Galactic bulge, and find enhanced alpha element abundances, consistent with the earlier work of McWilliam & Rich (1994). We also report on a radial velocity survey of {\sl 2MASS}-selected M giant stars in the Galactic bulge, observed with the CTIO 4m Hydra multi-object spectrograph. This program is to test dynamical models of the bulge and to search for and map any dynamically cold substructure in the Galactic bulge. We show initial results on fields at $-10^{\circ} < l <+10^{\circ}$ and $b=-4^{\circ}$. We construct a longitude-velocity plot for the bulge stars and the model data, and find that contrary to previous studies, the bulge does not rotate as a solid body; from $-5^{\circ}<l<+5^{\circ}$ the rotation curve has a slope of $\approx 100 km s^{-1}$ and flattens considerably at greater $l$ and reaches a maximum rotation of $45 {km s^{-1}}$ (heliocentric) or $\sim 70 {km s^{-1}}$ (Galactocentric). This rotation is slower than that predicted by the dynamical model of Zhao (1996).Comment: 6 pages, 6 figures, contributed paper at IAU Symposium 245 "Formation and Evolution of Galactic Bulges

HPV Awareness, Knowledge and Attitudes among Older African-American Women

Objective: To assess correlates of human papillomavirus (HPV) awareness, knowledge, and attitudes among older, church-going African-American women.ﾠMethods: Participants (N = 759), aged 40-80, answered survey questions about HPV awareness, knowledge, and attitudes toward vaccination of adolescent daughters. Associations between participant characteristics and HPV items were assessed using chi-square tests and logistic regression analyses.ﾠResults: Younger age, higher education, a family history of cancer, and less spirituality were each associated with HPV awareness individually, and when considered jointly in a single model (p values <.038). Higher education was related to HPV knowledge (p = .006).ﾠConclusions: African-American women of older age, less education, no family history of cancer, and/or higher spirituality might benefit from targeted church-based HPV educational campaigns

The Initial-Final Mass Relation: Direct Constraints at the Low Mass End

The initial-final mass relation represents a mapping between the mass of a white dwarf remnant and the mass that the hydrogen burning main-sequence star that created it once had. The relation thus far has been constrained using a sample of ~40 stars in young open clusters, ranging in initial mass from ~2.75 -- 7 Msun, and shows a general trend that connects higher mass main-sequence stars with higher mass white dwarfs. In this paper, we present CFHT/CFH12K photometric and Keck/LRIS multiobject spectroscopic observations of a sample of 22 white dwarfs in two older open clusters, NGC 7789 (t = 1.4 Gyr) and NGC 6819 (t = 2.5 Gyr). We measure masses for the highest S/N spectra by fitting the Balmer lines to atmosphere models and place the first direct constraints on the low mass end of the initial-final mass relation. Our results indicate that the observed general trend at higher masses continues down to low masses, with M_initial = 1.16 Msun main-sequence stars forming M_final = 0.53 Msun white dwarfs (including our data from the very old open cluster, NGC 6791). This extention of the relation represents a four fold increase in the total number of hydrogen burning stars for which the integrated mass loss can now be calculated, assuming a Salpeter initial mass function. The new leverage at the low mass end is used to derive a purely empirical initial-final mass relation without the need for any indirectly derived anchor points. The sample of white dwarfs in these clusters also shows several very interesting systems that we discuss further: a DB (helium atmosphere) white dwarf, a magnetic white dwarf, a DAB (mixed hydrogen/helium atmosphere or a double degenerate DA+DB) white dwarf(s), and two possible equal mass DA double degenerate binary systems.Comment: 18 pages, 12 figures, 3 tables. Submitted to Astrophys. J. Revised from first versio

Deep Photometry in a Remote M31 Major Axis Field Near G1

We present photometry from Hubble Space Telescope (HST)/Wide Field Planetary Camera 2 parallel imagery of a remote M31 field at a projected distance of about 34 kpc from the nucleus near the SW major axis. This field is near the globular cluster G1, and near one of the candidate tidal plumes identified by Ferguson et al. (2002). The F606W (V) and F814W (I) images were obtained in parallel with Space Telescope Imaging Spectrograph spectroscopy of G1 (GO-9099) and total 7.11 hours of integration time -- the deepest HST field in the outer disk of M31 to date, reaching to V ~ 28. The color-magnitude diagram of the field shows a clearly-defined red clump at V = 25.25 and a red giant branch consistent with [Fe/H] ~ -0.7. The lack of a blue horizontal branch contrasts with other M31 halo fields, the Andromeda dwarf spheroidals, and with the nearby globular cluster G1. Comparing the observed luminosity function to the Padova models, we find that at least some of the stellar population must be younger than 6 - 8 Gyr. The outermost detected neutral hydrogen gas disk of M31 lies only 2 kpc in projection from our field. The finding that some giants in the field have radial velocities close to that of the neutral hydrogen gas (Reitzel, Guhathakurta, & Rich 2003) leads us to conclude that our field samples the old, low-surface-brightness disk rather than the true Population II spheroid.Comment: 15 pages, 3 figures. accepted for publication in the A

Kinematics and Metallicity of M31 Red Giants: The Giant Southern Stream and Discovery of a Second Cold Component at R = 20 kpc

We present spectroscopic observations of red giant branch (RGB) stars in the Andromeda spiral galaxy (M31), acquired with the DEIMOS instrument on the Keck II 10-m telescope. The three fields targeted in this study are in the M31 spheroid, outer disk, and giant southern stream. In this paper, we focus on the kinematics and chemical composition of RGB stars in the stream field located at a projected distance of R = 20 kpc from M31's center. A mix of stellar populations is found in this field. M31 RGB stars are isolated from Milky Way dwarf star contaminants using a variety of spectral and photometric diagnostics. The radial velocity distribution of RGB stars displays a clear bimodality -- a primary peak centered at v = -513 km/s and a secondary one at v = -417 km/s -- along with an underlying broad component that is presumably representative of the smooth spheroid of M31. Both peaks are found to be dynamically cold with intrinsic velocity dispersions of sigma(v) = 16 km/s. The mean metallicity and metallicity dispersion of stars in the two peaks is also found to be similar: [Fe/H] = -0.45 and sigma([Fe/H]) = 0.2. The observed velocity of the primary peak is consistent with that predicted by dynamical models for the stream, but there is no obvious explanation for the secondary peak. The nature of the secondary cold population is unclear: it may represent: (1) tidal debris from a satellite merger event that is superimposed on, but unrelated to, the giant southern stream; (2) a wrapped around component of the giant southern stream; (3) a warp or overdensity in M31's disk at R > 50 kpc (this component is well above the outward extrapolation of the smooth exponential disk brightness profile).Comment: 32 pages, 13 figures, 1 table. Accepted for publication in Ap