scholarly journals The Magellanic Edges Survey I: Description and first results

2020 ◽  
Vol 497 (3) ◽  
pp. 3055-3075
Author(s):  
L R Cullinane ◽  
A D Mackey ◽  
G S Da Costa ◽  
S E Koposov ◽  
V Belokurov ◽  
...  
Keyword(s):  
Target Selection ◽  
Radial Distance ◽  
Large Magellanic Cloud ◽  
Disc Model ◽  
Observation Strategy ◽  
First Results ◽  
Mass Estimate ◽  
Red Clump ◽  
Red Giant ◽  
Giant Branch Stars

ABSTRACT We present an overview of, and first science results from, the Magellanic Edges Survey (MagES), an ongoing spectroscopic survey mapping the kinematics of red clump and red giant branch stars in the highly substructured periphery of the Magellanic Clouds. In conjunction with Gaia astrometry, MagES yields a sample of ~7000 stars with individual 3D velocities that probes larger galactocentric radii than most previous studies. We outline our target selection, observation strategy, data reduction, and analysis procedures, and present results for two fields in the northern outskirts (>10° on-sky from the centre) of the Large Magellanic Cloud (LMC). One field, located in the vicinity of an arm-like overdensity, displays apparent signatures of perturbation away from an equilibrium disc model. This includes a large radial velocity dispersion in the LMC disc plane, and an asymmetric line-of-sight velocity distribution indicative of motions vertically out of the disc plane for some stars. The second field reveals 3D kinematics consistent with an equilibrium disc, and yields Vcirc = 87.7 ± 8.0 km s−1 at a radial distance of ~10.5 kpc from the LMC centre. This leads to an enclosed mass estimate for the LMC at this radius of (1.8 ± 0.3) × 1010 M⊙.

scholarly journals The Stellar Populations of M32: Resolving the nearest elliptical with HST ACS/HRC

2009 ◽  
Vol 5 (S262) ◽  
pp. 135-138 ◽  
Author(s):  
Antonela Monachesi ◽  
S. C. Trager ◽  
Tod R. Lauer ◽  
Wendy Freedman ◽  
Alan Dressler ◽  
...  
Keyword(s):  
Stellar Population ◽  
Asymptotic Giant Branch ◽  
Asymptotic Giant Branch Stars ◽  
Horizontal Branch ◽  
Horizontal Branch Stars ◽  
Magnitude Diagram ◽  
Colour Distribution ◽  
Red Clump ◽  
Red Giant ◽  
Giant Branch Stars

AbstractWe present the deepest colour-magnitude diagram (CMD) of M32 to date, obtained from deep (F435W, F555W) photometry of HST ACS/HRC images. Due to the high resolution of our images, the small photometric errors, and the completeness level of our data we obtain the most detailed resolved photometric study of M32 to date. The CMD of M32 displays a wide colour distribution of red giant branch stars, mainly due to a metallicity spread, a strong red clump and bright asymptotic giant branch stars. The detection of a “blue plume” in M32 indicates the presence of a very young stellar population. There is not a noticeable presence of blue horizontal branch stars, suggesting that an old population with [Fe/H] < −1.5 does not significantly contribute to the light or mass of M32 in our observed fields.

scholarly journals Red variables in the OGLE-II database: first results for the LMC

2004 ◽  
Vol 193 ◽  
pp. 55-59
Author(s):  
L.L. Kiss ◽  
T.R. Bedding
Keyword(s):  
Large Magellanic Cloud ◽  
Variable Stars ◽  
Red Giants ◽  
Period Analysis ◽  
Short Period ◽  
First Results ◽  
Red Giant ◽  
Single Epoch ◽  
Low Amplitude ◽  
Radial Pulsations

AbstractWe present a period analysis of more then 23 000 red giants in the Large Magellanic Cloud observed by the OGLE-II microlensing project. Periods combined with the single-epoch 2MASS J H KS magnitudes revealed the complex distributions of stars in the period-luminosity plane. Besides four different sequences corresponding to different modes of pulsation in AGB stars, we also discovered two distinct and well-separated sequences below the tip of the Red Giant Branch, consisting of almost 10000 short-period and low-amplitude red variable stars. We propose that the majority are likely to be first ascent red giants, showing radial pulsations in the second and third overtone modes.

scholarly journals Mapping the stellar age of the Milky Way bulge with the VVV

2020 ◽  
Vol 644 ◽  
pp. A140 ◽  
Author(s):  
F. Surot ◽  
E. Valenti ◽  
O. A. Gonzalez ◽  
M. Zoccali ◽  
E. Sökmen ◽  
...  
Keyword(s):  
Galactic Plane ◽  
Interstellar Extinction ◽  
Star Formation History ◽  
Galactic Bulge ◽  
Formation History ◽  
Color Excess ◽  
Infrared Surveys ◽  
Red Clump ◽  
Red Giant ◽  
Giant Branch Stars

Context. A detailed study of the Galactic bulge stellar population necessarily requires an accurate representation of the interstellar extinction, particularly toward the Galactic plane and center, where severe and differential reddening is expected to vary on sub-arcmin scales. Although recent infrared surveys have addressed this problem by providing extinction maps across the whole Galactic bulge area, dereddened color-magnitude diagrams near the plane and center appear systematically undercorrected, prompting the need for higher resolution. These undercorrections affect any stellar study sensitive to color (e.g., star formation history analyses via color-magnitude diagram fitting), either making them inaccurate or limiting them to small and relatively stable extinction windows where this value is low and better constrained. Aims. This study is aimed at providing a high-resolution (2 arcmin to ∼10 arcsec) color excess map for the VVV bulge area in J − Ks color. Methods. We used the MW-BULGE-PSFPHOT catalogs, sampling ∼300 deg2 across the Galactic bulge (|l| < 10° and −10° < b <  5°) to isolate a sample of red clump and red giant branch stars, for which we calculated the average J − Ks color in a fine spatial grid in (l, b) space. Results. We obtained an E(J − Ks) map spanning the VVV bulge area of roughly 300 deg2, with the equivalent of a resolution between ∼1 arcmin for bulge outskirts (l <  6°) to below 20 arcsec within the central |l| < 1°, and below 10 arcsec for the innermost area (|l| < 1° and |b| < 3°).

scholarly journals The mass of the Milky Way out to 100 kpc using halo stars

2020 ◽  
Author(s):  
Alis J Deason ◽  
Denis Erkal ◽  
Vasily Belokurov ◽  
Azadeh Fattahi ◽  
Facundo A Gómez ◽  
...  
Keyword(s):  
Distribution Function ◽  
Mass Concentration ◽  
Milky Way ◽  
Function Analysis ◽  
Large Magellanic Cloud ◽  
Systematic Bias ◽  
Cosmological Simulations ◽  
Halo Stars ◽  
Systematic Effects ◽  
Mass Estimate

Abstract We use a distribution function analysis to estimate the mass of the Milky Way out to 100 kpc using a large sample of halo stars. These stars are compiled from the literature, and the vast majority ($\sim \! 98\%$) have 6D phase-space information. We pay particular attention to systematic effects, such as the dynamical influence of the Large Magellanic Cloud (LMC), and the effect of unrelaxed substructure. The LMC biases the (pre-LMC infall) halo mass estimates towards higher values, while realistic stellar halos from cosmological simulations tend to underestimate the true halo mass. After applying our method to the Milky Way data we find a mass within 100 kpc of M( &lt; 100kpc) = 6.07 ± 0.29(stat.) ± 1.21(sys.) × 1011M⊙. For this estimate, we have approximately corrected for the reflex motion induced by the LMC using the Erkal et al. model, which assumes a rigid potential for the LMC and MW. Furthermore, stars that likely belong to the Sagittarius stream are removed, and we include a 5% systematic bias, and a 20% systematic uncertainty based on our tests with cosmological simulations. Assuming the mass-concentration relation for Navarro-Frenk-White haloes, our mass estimate favours a total (pre-LMC infall) Milky Way mass of M200c = 1.01 ± 0.24 × 1012M⊙, or (post-LMC infall) mass of M200c = 1.16 ± 0.24 × 1012 M⊙ when a 1.5 × 1011M⊙ mass of a rigid LMC is included.

scholarly journals A Keck/Deimos Survey of Red Giant Branch Stars in the Outskirts of M31

2006 ◽  
pp. 286-291 ◽  
Author(s):  
Annette M. N. Ferguson ◽  
Scott Chapman ◽  
Rodrigo Ibata ◽  
Mike Irwin ◽  
Geraint Lewis ◽  
...  
Keyword(s):  
Red Giant ◽  
Giant Branch Stars
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