A cluster of intermediate age in the Large Magellanic Cloud

1964 ◽  
Vol 20 ◽  
pp. 347-348
Author(s):  
Richard Woolley
Keyword(s):  
Variable Star ◽  
Open Cluster ◽  
Large Magellanic Cloud ◽  
Proper Motions ◽  
Giant Stars ◽  
Tight Cluster ◽  
Faint Object ◽  
Bright Blue ◽  
Star Field ◽  
Hr Diagram

Some years ago (1960) I discussed the HR diagram of the variable star field investigated at Herstmonceux as the result of Drs. Sandage and Eggen's visit to Pretoria, and found colour-luminosity arrays showing mainly very blue giant stars; and later (1961) I suggested that a second and older population could be seen in the same area of the LMC, showing a rather different x,y distribution. Recently Miss Epps has assisted me to make further investigations into the matter. We are now discussing stars fainter than V = 14 · 5 and therefore too faint for us to determine their proper motions. In order to get rid of foreground stars which obscure the HR diagram we have had to make use of the x, y distribution to discriminate between LMC members and foreground stars. Firstly, we examined an open cluster which appears as a faint object on the 74-inch Pretoria plates. It is away from the main lane occupied by the bright blue objects, and its appearance on the B and V plates showed it not to be excessively blue. On a Radcliffe plate (74 in. stopped to 44 in.) with an exposure of 20 min, 29 stars can be seen within a circle of diameter of 1′ of arc. We have been able to determine V accurately for only 15 of these stars, one of which proved to be a variable of period 4–75 days. The HR diagram shows a gap between B – V = 0 · 2 and B – V = 1 · 0, the variable being in this gap. It is comparable with those of NGC 129, NGC 2287, and NGC 6067, and, by analogy with these objects, the open cluster now described probably has an age of about 108 years. The object is of course very different from the young or blue (but tight) cluster NGC 1818 not far away from it.

scholarly journals NGC 2587: a sparse open cluster projected onto a populous star field

2009 ◽  
Vol 5 (S266) ◽  
pp. 504-507
Author(s):  
Andrés E. Piatti ◽  
Juan J. Clariá ◽  
Andrea V. Ahumada
Keyword(s):  
Heliocentric Distance ◽  
Open Cluster ◽  
Interstellar Extinction ◽  
New Method ◽  
Proper Motions ◽  
Solar Metallicity ◽  
Cluster Values ◽  
Star Field

AbstractWe present CCD BVIKC photometry in the field of the open cluster NGC 2587. We developed a new method to clean statistically the colour–magnitude diagrams. NGC 2587 is found to be slightly younger than the Hyades and probably of solar metallicity. From 18 probable members with measured proper motions, we derived the following mean cluster values: μα = −4.3 ± 3.6 mas yr−1 and μδ = −2.5 ± 3.4 mas yr−1. Colour excesses, E(B − V) = 0.10 and E(V − I) = 0.15 mag, and a heliocentric distance of 3.7 ± 0.7 kpc are obtained. The interstellar extinction in the cluster direction is found to follow the normal reddening law.

scholarly journals Analysis of the Open Cluster NGC 2281

Galaxies ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 7
Author(s):  
Dirk Terrell ◽  
John Gross ◽  
Walter R. Cooney
Keyword(s):  
Variable Star ◽  
American Association ◽  
Open Cluster ◽  
Standard System ◽  
Proper Motions ◽  
Eclipsing Binary ◽  
Photometric Observations ◽  
Sky Survey ◽  
Gaia Dr2

BV observations of an approximately 68′×48′ field centered on the open cluster NGC 2281 and covering more than 400 nights from 2013 to 2018 are presented. The photometric observations were transformed to the standard system using standards from the American Association of Variable Star Observers Photometric All-sky Survey (APASS) DR10 and analyzed with Gaia DR2 parallaxes and proper motions to determine the distance, age, and metallicity of the cluster. The discovery of an eclipsing binary in the field is discussed.

NGC 6124: a young open cluster with anomalous- and fast-rotating giant stars

2021 ◽  
Author(s):  
N Holanda ◽  
N Drake ◽  
W J B Corradi ◽  
F A Ferreira ◽  
F Maia ◽  
...  
Keyword(s):  
Isotopic Ratio ◽  
Rotational Velocity ◽  
Open Cluster ◽  
Chemical Species ◽  
Stellar Atmospheres ◽  
Lithium Abundance ◽  
Giant Stars ◽  
Analysis Technique ◽  
Young Open Cluster ◽  
Fast Rotating

Abstract We present the results of a chemical analysis of fast and anomalous rotator giants members of the young open cluster NGC 6124. For this purpose, we carried out abundances of the mixing sensitive species such as Li, C, N, Na and 12C/13C isotopic ratio, as well as other chemical species for a sample of four giants among the seven observed ones. This study is based on standard spectral analysis technique using high-resolution spectroscopic data. We also performed an investigation of the rotational velocity (v sin  i) once this sample exhibit abnormal values – giant stars commonly present rotational velocities of few km s−1. In parallel, we have been performed a membership study, making use of the third data release from ESA Gaia mission. Based on these data, we estimated a distance of d = 630 pc and an age of 178 Myr through isochrone fitting. After that procedure, we matched all the information raised and investigated the evolutionary stages and thermohaline mixing model through of spectroscopic Teff and log  g and mixing tracers, as 12C/13C and Na, of the studied stars. We derived a low mean metallicity of [Fe/H] = −0.13 ±0.05 and a modest enhancement of the elements created by the s-process such as Y, Zr, La, Ce, and Nd, which is in agreement of what has already been reported in the literature for young clusters. The giants analyzed have homogeneous abundances, except for lithium abundance [log  ε(Li)NLTE = 1.08±0.42] and this may be associated to a combination of mechanisms that act increasing or decreasing lithium abundances in stellar atmospheres.

scholarly journals The MACHO Project Large Magellanic Cloud Variable Star Inventory. XI. Frequency Analysis of the Fundamental‐Mode RR Lyrae Stars

2003 ◽  
Vol 598 (1) ◽  
pp. 597-609 ◽  
Author(s):  
C. Alcock ◽  
D. R. Alves ◽  
A. Becker ◽  
D. Bennett ◽  
K. H. Cook ◽  
...  
Keyword(s):  
Frequency Analysis ◽  
Fundamental Mode ◽  
Variable Star ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Lyrae Stars

scholarly journals OCCASO – III. Iron peak and α elements of 18 open clusters. Comparison with chemical evolution models and field stars

2019 ◽  
Vol 490 (2) ◽  
pp. 1821-1842 ◽  
Author(s):  
L Casamiquela ◽  
S Blanco-Cuaresma ◽  
R Carrera ◽  
L Balaguer-Núñez ◽  
C Jordi ◽  
...  
Keyword(s):  
Chemical Evolution ◽  
Open Cluster ◽  
Dynamical Evolution ◽  
Open Clusters ◽  
Chemical Abundances ◽  
Homogeneous Sample ◽  
Giant Stars ◽  
Stellar Nucleosynthesis ◽  
Solar Abundances ◽  
Red Giant

ABSTRACT The study of open-cluster chemical abundances provides insights on stellar nucleosynthesis processes and on Galactic chemo-dynamical evolution. In this paper we present an extended abundance analysis of 10 species (Fe, Ni, Cr, V, Sc, Si, Ca, Ti, Mg, O) for red giant stars in 18 OCCASO clusters. This represents a homogeneous sample regarding the instrument features, method, line list and solar abundances from confirmed member stars. We perform an extensive comparison with previous results in the literature, and in particular with the Gaia FGK Benchmark stars Arcturus and $\mu$-Leo. We investigate the dependence of [X/Fe] with metallicity, Galactocentric radius (6.5 kpc < RGC < 11 kpc), age (0.3 Gyr < Age < 10 Gyr), and height above the plane (|z| < 1000 pc). We discuss the observational results in the chemo-dynamical framework, and the radial migration impact when comparing with chemical evolution models. We also use APOGEE DR14 data to investigate the differences between the abundance trends in RGC and |z| obtained for clusters and for field stars.

Relative proper motions in the region of the open cluster NGC 1664.

1973 ◽  
Vol 78 ◽  
pp. 53 ◽  
Author(s):  
S. J. Kerridge ◽  
R. M. Nelson ◽  
W. S. Mesrobian
Keyword(s):  
Open Cluster ◽  
Proper Motions

Five-color photometry of variable star field IV in M31

1964 ◽  
Vol 69 ◽  
pp. 610 ◽  
Author(s):  
Sidney van den Bergh
Keyword(s):  
Variable Star ◽  
Star Field

Proper motions of stars in the open cluster M 37.

1966 ◽  
Vol 71 ◽  
pp. 736 ◽  
Author(s):  
A. R. Upgren
Keyword(s):  
Open Cluster ◽  
Proper Motions

scholarly journals Dark and luminous satellites of LMC-mass galaxies in the FIRE simulations

2019 ◽  
Vol 489 (4) ◽  
pp. 5348-5364 ◽  
Author(s):  
Ethan D Jahn ◽  
Laura V Sales ◽  
Andrew Wetzel ◽  
Michael Boylan-Kolchin ◽  
T K Chan ◽  
...  
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Dwarf Galaxies ◽  
Large Magellanic Cloud ◽  
Proper Motions ◽  
New Members ◽  
Cosmological Context ◽  
Luminosity Functions ◽  
In Fire ◽  
Number Counts

ABSTRACT Within lambda cold dark matter ($\Lambda$CDM), dwarf galaxies like the Large Magellanic Cloud (LMC) are expected to host numerous dark matter subhaloes, several of which should host faint dwarf companions. Recent Gaia proper motions confirm new members of the LMC system in addition to the previously known SMC, including two classical dwarf galaxies ($M_\ast$$\gt 10^5$ M$_{\odot }$; Carina and Fornax) as well as several ultrafaint dwarfs (Car2, Car3, Hor1, and Hyd1). We use the Feedback In Realistic Environments (FIRE) simulations to study the dark and luminous (down to ultrafaint masses, $M_\ast$$\sim$6$\times 10^ {3}$ M$_{\odot }$) substructure population of isolated LMC-mass hosts ($M_{\text{200m}}$ = 1–3$\times 10^ {11}$ M$_{\odot }$) and place the Gaia  + DES results in a cosmological context. By comparing number counts of subhaloes in simulations with and without baryons, we find that, within 0.2 $r_{\text{200m}}$, LMC-mass hosts deplete $\sim$30 per cent of their substructure, significantly lower than the $\sim$70 per cent of substructure depleted by Milky Way (MW) mass hosts. For our highest resolution runs ($m_\text{bary}$  = 880 M$_{\odot }$), $\sim 5\!-\!10$ subhaloes form galaxies with $M_\ast$$\ge 10^{4}$ M$_{\odot }$ , in agreement with the seven observationally inferred pre-infall LMC companions. However, we find steeper simulated luminosity functions than observed, hinting at observation incompleteness at the faint end. The predicted DM content for classical satellites in FIRE agrees with observed estimates for Carina and Fornax, supporting the case for an LMC association. We predict that tidal stripping within the LMC potential lowers the inner dark matter density of ultrafaint companions of the LMC. Thus, in addition to their orbital consistency, the low densities of dwarfs Car2, Hyd1, and Hyd2 reinforce their likelihood of Magellanic association.

scholarly journals The mass of our Galaxy from satellite proper motions in the Gaia era

2020 ◽  
Vol 494 (4) ◽  
pp. 5178-5193 ◽  
Author(s):  
T K Fritz ◽  
A Di Cintio ◽  
G Battaglia ◽  
C Brook ◽  
S Taibi
Keyword(s):  
Milky Way ◽  
Anisotropy Parameter ◽  
Large Magellanic Cloud ◽  
Mass Determination ◽  
Proper Motions ◽  
Radial Density ◽  
Full Sample ◽  
Scale Free ◽  
Virial Mass ◽  
Gaia Dr2

ABSTRACT We use Gaia DR2 systemic proper motions of 45 satellite galaxies to constrain the mass of the Milky Way using the scale-free mass estimator of Watkins et al. (2010). We first determine the anisotropy parameter β, and the tracer satellites’ radial density index γ to be β = $-0.67^{+0.45}_{-0.62}$ and γ = 2.11 ± 0.23. When we exclude possible former satellites of the Large Magellanic Cloud, the anisotropy changes to β = $-0.21^{+0.37}_{-0.51}$. We find that the index of the Milky Way’s gravitational potential α, which is dependent on the mass itself, is the parameter with the largest impact on the mass determination. Via comparison with cosmological simulations of Milky Way-like galaxies, we carried out a detailed analysis of the estimation of the observational uncertainties and their impact on the mass estimator. We found that the mass estimator is biased when applied naively to the satellites of simulated Milky Way haloes. Correcting for this bias, we obtain for our Galaxy a mass of $0.58^{+0.15}_{-0.14}\times 10^{12}$ M⊙ within 64 kpc, as computed from the inner half of our observational sample, and $1.43^{+0.35}_{-0.32}\times 10^{12}$ M⊙ within 273 kpc, from the full sample; this latter value extrapolates to a virial mass of $M_\mathrm{vir\, \Delta =97}=1.51^{+0.45}_{-0.40} \times 10^{12}\,{\rm M}_{\odot }$ corresponding to a virial radius of Rvir = 308 ± 29 kpc. This value of the Milky Way mass lies in-between other mass estimates reported in the literature, from various different methods.

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