Recent observations have shown that globular clusters contain a significant binary population. This is dramatic change from the conventional view of even decade ago, which held formed without any binaries at all, since observed X-ray were understood to be through dynamical capture. Over last few years, number different observational techniques resulted in detection substantial most are believed primordial. When many selection effects taken into account, these detections translate abundance...

We analyze HST/STIS spectra (see Paper I) of the central region dense globular cluster M15. infer velocities 64 individual stars, two-thirds which have their velocity measured for first time. This triples number stars with in 1 arcsec M15 and doubles 2 arcsec. Combined existing ground-based data we obtain radial profiles projected kinematical quantities. The RMS sigma_RMS rises to 14 km/s few arcsec, somewhat higher than values 10-12 inferred previously from data. To interpret results...

We have used HST imaging of the central regions globular cluster 47 Tucanae (=NGC 104), taken with WFPC2 and ACS instruments between 1995 2002, to derive proper motions U- V-band magnitudes for 14,366 stars within 100'' (about 5 core radii) center. This represents largest set member velocities collected any cluster. The involved range in brightness from just fainter than horizontal branch more 2.5 mag below main-sequence turnoff. In course obtaining these kinematic data, we also use a recent...

Kallivayalil et al. have used the Hubble Space Telescope to measure proper motions of Large Magellanic Cloud (LMC) and Small (SMC) using images in 21 five fields, respectively, all centered on known quasi-stellar objects (QSOs). These results are more precise than previous measurements, but surprising important physical implications: for example, LMC SMC may be approaching Milky Way first time; they might not been a binary system; origin Stream needs re-examined. Motivated by these...

Using WFPC2 on the Hubble Space Telescope, we have isolated a sample of 258 white dwarfs (WDs) in Galactic globular cluster M4. Fields at three radial distances from center were observed, and sizable WD populations found all three. The location these WDs color-magnitude diagram, their mean mass 0.51(±0.03) M☉, luminosity function confirm basic tenets stellar evolution theory support results current cooling theory. are used to extend main-sequence upward stars that already completed nuclear...

We have performed numerical simulations to investigate whether galactic tides can elevate the apparent mass-to-light ratio (M/L) in a dwarf spheroidal galaxy (dSph). In our dSph is composed only of luminous matter and falls towards Milky Way on various orbits potentials starting from apogalacticon. assume single perigalacticon passage which close encounter with produces strong that greatly affect structure kinematics dSph. find even when dSph, they fail inflate central M/L. Tides produce...

view Abstract Citations (148) References (76) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Carina Dwarf Spheroidal Galaxy: How Dark is it? Mateo, Mario ; Olszewski, Edward W. Pryor, Carlton Welch, Douglas L. Fischer, Philippe We have obtained precise (<σ> = 3.1 km s^-1^) radial velocities of 23 photometrically-selected normal giant stars located near the center dwarf spheroidal (dSph) galaxy. Of this sample, 17 are members based on their heliocentric...

We have measured 206 radial velocities for 94 probable members in the Ursa Minor dwarf spheroidal galaxy and 167 91 Draco galaxy. These were obtained using KPNO 4 m telescope with Hydra multifiber positioner bench spectrograph 1992,1993, 1994. Both simulations repeated measurements show that median uncertainty these is 4.0 km/s. Our are compared other major datasets Minor. Aside from a small zero-point difference, there excellent agreement between Olszewski et al. MMT echelle velocities....

This article presents a measurement of the proper motion Ursa Minor dwarf spheroidal galaxy determined from images taken with Hubble Space Telescope in two distinct fields.

The measured proper motion of Fornax, expressed in the equatorial coordinate system, is $(\mu_{\alpha},\mu_{\delta})=(47.6\pm 4.6,-36.0\pm 4.1)$ mas century$^{-1}$. This a weighted mean four independent measurements for three distinct fields. Each measurement uses quasi-stellar object as reference point. Removing contribution Sun and Local Standard Rest to produces Galactic rest-frame $(\mu_{\alpha}^{\mbox{\tiny{Grf}}}, \mu_{\delta}^{\mbox{\tiny{Grf}}}) = (24.4\pm 4.6,-14.3\pm implied space...

view Abstract Citations (92) References (21) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The formation of galaxies from massive neutrinos Davis, M. ; Lecar, Pryor, C. Witten, E. Scenarios are described that, by including an unstable tau-neutrino, facilitated galaxy formation. Although the particle is chosen to be it noted that another (perhaps not a neutrino at all) with similar mass, lifetime, and decoupling time would serve as well. Without massive,...

We have used an Imaging Fabry-Perot Spectrophotometer with the Adaptive Optics Bonnette on Canada-France-Hawaii Telescope to measure stellar radial velocities in globular cluster M15 (NGC 7078). An average seeing of 015 FWHM, best-seeing image having 009, allowed us accurately for five stars within 1'' center M15. Our estimate second moment velocity distribution (i.e., dispersion, ignoring rotation) inside a radius 2'' is 11.5 km s-1, same value we find out about 6''. However, projected net...

We use a large set of radial velocities in the Ursa Minor and Draco dwarf spheroidal galaxies to search for binary stars infer frequency. Of 118 our sample with multiple observations, six are velocity variables $χ^2$ probabilities below 0.001. Monte Carlo simulations that mimic observations determine efficiency which find stars. Our best, though significantly uncertain, estimate frequency near turnoff UMi is 0.2--0.3 per decade period vicinity periods one year, 3--5$\times$ found solar...

This article presents and discusses a measurement of the proper motion for Carina dwarf spheroidal galaxy (dSph) from images in two distinct fields direction taken with Hubble Space Telescope, at three epochs. Each field contains confirmed quasi-stellar object that is reference point measuring dSph. The consecutive epochs are 1–2 yr apart. components measured Carina, expressed equatorial coordinate system, μα = 22 ± 9 mas century-1 μδ 15 century-1. quoted weighted mean independent...

This article presents a measurement of the proper motion Sculptor dwarf spheroidal galaxy determined from images taken with Hubble Space Telescope using Imaging Spectrograph in imaging mode. Each two distinct fields contains quasi-stellar object that serves as "reference point." The measured Sculptor, expressed equatorial coordinate system, is (μα, μδ) = (9 ± 13, 2 13) mas century-1. Removing contributions Sun and local standard rest produces Galactic frame: (μ, μ) (-23 45 implied space...

We have carried out Wide Field Planetary Camera 2 V- and I-band imaging of the young LMC cluster NGC 2157. Construction a color-magnitude diagram isochrone fitting yield an age τ = 108 yr, reddening E(B - V) 0.1, distance modulus 18.4 mag. Our data cover mass range 0.75 M⊙ ≤ m 5.1 M⊙. find that function changes significantly from inner regions to outer regions, becoming steeper (larger number low-mass stars relative high-mass stars) at larger radii. The 2157 is comparable its two-body...

It has been reported that there is an error in the figure Dull et al. (1997, D97) shows radial M/L profile Fokker-Planck models of M15. We discuss how this modifies interpretation our kinematical data. These imply existence a dark and compact mass component near center M15, either single black hole (BH) or collection remnants have sunk to cluster due segregation. previously showed latter conflict with D97 profile, which supported BH interpretation. repeat analysis here corrected profile....

view Abstract Citations (95) References (31) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Dark Matter Halos of Draco and Ursa Minor Pryor, Carlton ; Kormendy, John Published density profiles central velocity dispersions place important constraints on the stellar ellipsoid distribution dark matter (DM) in dwarf spheroidal galaxies Minor. We adopt 9 km s^-1^ for 11 Then, an isotropic distribution, DM densities are ρ_0D_ = 0.8 1.0 M_sun_ pc^-3^,...

view Abstract Citations (77) References (45) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Age Gradient and the Second Parameter Problem in Galactic Halo Richer, Harvey B. ; Harris, William E. Fahlman, Gregory G. Bell, Roger A. Bond, Howard Hesser, James Holland, Steve Pryor, Carlton Stetson, Peter Vandenberg, Don van den Bergh, Sidney We establish a framework for determining absolute ages of globular clusters then use these to investigate age-metallicity...

Using the Rutgers Imaging Fabry-Perot Spectrophotometer on CTIO 4-m telescope, we have measured radial velocities for 548 stars in 47 Tuc (NGC 104), 128 NGC 6397, and 132 M30 7099), with uncertainties between 0.5 5 km s<SUP>-1</SUP>. In dispersion profiles at first increase decreasing radii but then flatten central 0'.4. This is same behavior seen our previously published profile M15. The stellar show that rotating, a projected rotation axis aligned isophotal minor axis. We also find similar...

With the Wide Field Planetary Camera 2 (WFPC2) on Hubble Space Telescope, we have discovered in M4 (NGC 6121, C1620-264) first extensive sequence of cooling white dwarfs seen a globular cluster. Adopting distance modulus (m - M)V = 12.65 and reddening E(B V) 0.37, show that sequence, which extends over 9 < MU 13, is comprised mass ~0.5 M☉. The total loss from present turnoff to dwarf 0.31 M☉, intrinsic dispersion mean appears be <0.05 Both location cluster color-magnitude diagram cumulative...

This article presents and discusses a method for measuring the proper motions of Galactic dwarf spheroidal galaxies using images taken with Hubble Space Telescope. The involves fitting an effective point-spread function to image star or quasi-stellar object determine its centroid accuracy about 0.005 pixels (0.25 mas)—an sufficient measure motion galaxy, separated by just few years. data consist images, dithered reduce effects undersampling, at multiple epochs Telescope Imaging Spectrograph...

We have measured the proper motion of Draco dwarf galaxy using images at two epochs with a time baseline about years taken Hubble Space Telescope Advanced Camera for Surveys. Wide Field Channels 1 and 2 provide adjacent fields, each containing known QSO. The zero point is determined both background galaxies QSOs methods produce consistent measurements within field. Averaging results from fields gives in equatorial coordinate system mas century−1 Galactic century−1. Removing contributions Sun...

This article reports a measurement of the proper motion Leo II, dwarf galaxy that is likely satellite Milky Way, based on imaging with Hubble Space Telescope and Wide Field Camera 3. The uses compact background galaxies as standards rest in both channels camera for two distinct pointings telescope QSO one channel each pointing, resulting weighted average six measurements. measured equatorial coordinate system (mu_alpha, mu_delta) = (-6.9 +- 3.7, -8.7 3.9) mas/century Galactic (mu_l, mu_b)...

view Abstract Citations (66) References (38) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Fabry-Perot Measurements of the Dynamics Globular Cluster Cores: M15 (NGC 7078) Gebhardt, K. ; Pryor, C. Williams, T. B. Hesser, James E. We report first use Rutgers Imaging Spectrophotometer to study dynamics cores globular clusters. have obtained velocities for cluster stars by tuning take a series narrow-band images at different wavelengths across one Na D (5890...