scholarly journals Line of sight depth of the Large and Small Magellanic Clouds

2008 ◽  
Vol 4 (S256) ◽  
pp. 63-68
Author(s):  
Annapurni Subramaniam ◽  
Smitha Subramaniam
Keyword(s):  
Gravitational Lensing ◽  
Magellanic Clouds ◽  
Optical Center ◽  
Line Of Sight ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Colour Distribution ◽  
Red Clump ◽  
Minor Mergers ◽  
Lyrae Stars

AbstractWe used the red clump stars from the Optical Gravitational Lensing Experiment (OGLE II) survey and the Magellanic Cloud Photometric Survey (MCPS), to estimate the line-of-sight depth. The observed dispersion in the magnitude and colour distribution of red clump stars is used to estimate the line-of-sight depth, after correcting for the contribution due to other effects. This dispersion due to depth, has a range from minimum dispersion that can be estimated, to 0.46 mag (a depth of 500 pc to 10.44 kpc), in the LMC. In the case of the SMC, the dispersion ranges from minimum dispersion to 0.35 magnitude (a depth of 665 pc to 9.53 kpc). The thickness profile of the LMC bar indicates that it is flared. The average depth in the bar region is 4.0 ± 1.4 kpc. The halo of the LMC (using RR Lyrae stars) is found to have larger depth compared to the disk/bar, which supports the presence of an inner halo for the LMC. The large depth estimated for the LMC bar and the disk suggests that the LMC might have had minor mergers. In the case of the SMC, the bar depth (4.90 ± 1.23 kpc) and the disk depth (4.23 ± 1.48 kpc) are found to be within the standard deviations. We find evidence for an increase in depth near the optical center (up to 9 kpc). On the other hand, the estimated depth for the halo (RR Lyrae stars) and disk (RC stars) for the bar region of the SMC is found to be similar. Thus, increased depth and enhanced stellar as well as H i density near the optical center suggests that the SMC may have a bulge.

scholarly journals The Pisces Plume and the Magellanic wake

2019 ◽  
Vol 488 (1) ◽  
pp. L47-L52 ◽  
Author(s):  
Vasily Belokurov ◽  
Alis J Deason ◽  
Denis Erkal ◽  
Sergey E Koposov ◽  
Julio A Carballo-Bello ◽  
...  
Keyword(s):  
Milky Way ◽  
Galactic Halo ◽  
Magellanic Clouds ◽  
Line Of Sight ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Data Release ◽  
Magellanic Stream ◽  
Lyrae Stars

ABSTRACT Using RR Lyrae stars in the Gaia Data Release 2 and Pan-STARRS1 we study the properties of the Pisces overdensity, a diffuse substructure in the outer halo of the Milky Way. We show that along the line of sight, Pisces appears as a broad and long plume of stars stretching from 40 to 110 kpc with a steep distance gradient. On the sky Pisces’s elongated shape is aligned with the Magellanic Stream. Using follow-up VLT FORS2 spectroscopy, we have measured the velocity distribution of the Pisces candidate member stars and have shown it to be as broad as that of the Galactic halo but offset to negative velocities. Using a suite of numerical simulations, we demonstrate that the structure has many properties in common with the predicted behaviour of the Magellanic wake, i.e. the Galactic halo overdensity induced by the infall of the Magellanic Clouds.

scholarly journals RR Lyrae Variable Stars and the Distance Scale

1978 ◽  
Vol 80 ◽  
pp. 53-57
Author(s):  
S. V. M. Clube ◽  
J. A. Dawe
Keyword(s):  
Galactic Halo ◽  
Galactic Center ◽  
Variable Stars ◽  
Magellanic Clouds ◽  
Solar Neighborhood ◽  
Royal Greenwich Observatory ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Lyrae Stars ◽  
Kinematical Parameters

A statistical parallax algorithm (Clube and Dave, 1978a,b), using the technique of maximum likelihood, has been applied to a set of 103 ‘ab’ - RR Lyrae stars in the solar neighborhood (r 2<kpc), using observational data from the Royal Greenwich Observatory Bulletins. A second set of 130 ‘ab’ - RR Lyrae stars has been kindly supplied to us by Dr. A. Heck (Université de Liège) to permit a comparison between our analyses. The purpose of this investigation was:(a) to investigate the variations of kinematical parameters and absolute luminosities of these stars as functions of Preston's index ΔS and of log (Period).(b) to identify those RR Lyrae stars in the solar neighborhood which most closely resemble those in the galactic halo, those near the galactic center, and those in the Magellanic Clouds.

scholarly journals RR Lyrae Stars and Novae in the Magellanic Clouds

1984 ◽  
Vol 108 ◽  
pp. 207-215 ◽  
Author(s):  
J. A. Graham
Keyword(s):  
Variable Stars ◽  
Magellanic Clouds ◽  
Rr Lyrae Stars ◽  
Entire Area ◽  
Classical Novae ◽  
Rr Lyrae ◽  
Cloud Clusters ◽  
Large Numbers ◽  
Lyrae Stars ◽  
Made In

RR Lyrae variable stars and classical novae can be used very effectively for locating and studying the old stellar populations in the Magellanic Clouds. RR Lyrae stars are found in large numbers in both Clouds at about 19m. Apart from the concentrated searches within Cloud clusters, intensive surveys for field variables have so far been made in four areas, each about 1° square. Novae have the advantage of being as bright as 10m at maximum light. They can be detected with small telescopes and surveys have covered almost the entire area of each Cloud. Needs and prospects for future surveys are discussed. Both types of object are suitable for investigating the early chemical composition of the Clouds and its subsequent enrichment with heavy elements. Studies of the old populations in the Clouds are reinforcing the view that, while some stars in the Magellanic Clouds are as old as any in our Galaxy, the major bursts of star formation came along comparatively recently.

scholarly journals RR Lyraes in the Magellanic Clouds

1993 ◽  
Vol 139 ◽  
pp. 15-20
Author(s):  
Alistair R. Walker
Keyword(s):  
Recent Work ◽  
Galaxy Formation ◽  
Magellanic Clouds ◽  
Distance Modulus ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Star Studies ◽  
Absolute Magnitudes ◽  
Halo Population ◽  
Lyrae Stars

AbstractRecent work on the Magellanic Cloud RR Lyrae stars is reviewed. The absolute magnitudes of LMC RR Lyraes, when calibrated from a distance modulus of 18.5 mag, disagrees with the Galactic calibration. The revised distance scale makes distances greater, and ages younger, within our galaxy. Field star studies show that the “halo” population of the LMC is very similar to that of our own Galaxy outside of the solar circle. This result supports a Searle and Zinn model of galaxy formation.

scholarly journals The Characteristics of the Field RR Lyrae Stars in the Magellanic Clouds

1974 ◽  
Vol 59 ◽  
pp. 107-108
Author(s):  
J. A. Graham
Keyword(s):  
Stellar Evolution ◽  
Large Magellanic Cloud ◽  
Variable Stars ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Light Curves ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
First Results ◽  
Lyrae Stars

The Magellanic Clouds are well known as being very suitable for observing the various stages of stellar evolution. During the last few years, I have been studying the RR Lyrae variable stars in each of the two Clouds. Some first results were reported at IAU Colloquium No. 21 in 1972 (Graham, 1973). Here, I would like to update these results on the basis of more recent data and to comment on some of the characteristics of the field RR Lyrae stars in each system. Periods and light curves are now available for 63 RR Lyrae stars in a 1° x 1.3° field centered on the cluster NGC 1783 in the Large Magellanic Cloud (LMC) and for 62 stars in a 1° x 1.3° field centered on the cluster NGC 121 in the Small Magellanic Cloud (SMC). Both ab and c type variables are represented and, viewed individually, the Cloud RR Lyraes are identical in characteristics to those known in our Galaxy. Studied as groups, however, there are small but significant differences between the RR Lyrae stars in each system. The following four specific features seem to be emerging from the study.

scholarly journals The Distance to the Large Magellanic Cloud

2000 ◽  
Vol 176 ◽  
pp. 203-207
Author(s):  
Piotr Popowski
Keyword(s):  
Galactic Center ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Distance Modulus ◽  
Local Universe ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Red Clump ◽  
Lyrae Stars ◽  
Selective Extinction

AbstractI demonstrate that the two unexpected results in the local Universe: anomalous intrinsic (V – I)0 colors of RR Lyrae stars and clump giants in the Galactic center, and very short distances to Magellanic Clouds inferred from clump giants, can be at least partially resolved with a modified coefficient of selective extinction AV/E(V – I). With this modification, I find a new clump-giant distance modulus to the Large Magellanic Cloud, μLMC = 18.27 ± 0.07, which is 0.09 larger than the Udalski (1998b) result. When distance estimates from the red clump, RR Lyrae stars and the eclipsing binary HV2274 are combined, one obtains μLMC = 18.31 ± 0.04 (internal).

scholarly journals Kinematics of RR Lyrae stars in the Galactic bulge with OGLE-IV and Gaia DR2

2020 ◽  
Vol 498 (4) ◽  
pp. 5629-5642
Author(s):  
Hangci Du ◽  
Shude Mao ◽  
E Athanassoula ◽  
Juntai Shen ◽  
Pawel Pietrukowicz
Keyword(s):  
Velocity Dispersion ◽  
Line Of Sight ◽  
Proper Motions ◽  
Galactic Bulge ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Halo Stars ◽  
Central Regions ◽  
Lyrae Stars ◽  
Gaia Dr2

ABSTRACT We analyse the kinematics and spatial distribution of 15 599 fundamental-mode RR Lyrae (RRL) stars in the Milky Way bulge by combining OGLE-IV photometric data and Gaia DR2 proper motions. We show that the longitudinal proper motions and the line-of-sight velocities can give similar results for the rotation in the Galactic central regions. The angular velocity of bulge RRLs is found to be around 35 km s−1 kpc−1, significantly smaller than that for the majority of bulge stars (50–60 km s−1 kpc−1); bulge RRLs have larger velocity dispersion (120–140 km s−1) than younger stars. The dependence of the kinematics of the bulge RRLs on their metallicities is shown by their rotation curves and spatial distributions. Metal-poor RRLs ([Fe/H]<−1) show a smaller bar angle than metal-rich ones. We also find clues suggesting that RRLs in the bulge are not dominated by halo stars. These results might explain some previous conflicting results over bulge RRLs and help understand the chemodynamical evolution of the Galactic bulge.

scholarly journals The RR Lyrae Stars in the Magellanic Clouds

1973 ◽  
Vol 21 ◽  
pp. 120-128
Author(s):  
J. A. Graham
Keyword(s):  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Type I ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Visual Magnitude ◽  
Metal Abundance ◽  
Lyrae Stars ◽  
Small Dispersion

AbstractThe characteristics of the RR Lyrae stars in the Magellanic Clouds are discussed. The existence of numerous RR Lyrae variables in the Large Magellanic Cloud (LMC) cluster NGC 1835 is noted. The variables indicate that this cluster is of Oosterhoff type I. No cluster of Oosterhoff type II has yet been recognized in the Clouds. Some new results of a study of the RRLyrae variables in an LMC field 1° x 1.°3 are discussed. Periods have been determined for 50 out of 72 probable RR lyraes in this field. RR Lyrae ab stars with periods less than 0.d46 are absent. The time averaged and are 19.m56 and 19.m20 with surprisingly small dispersion. First impressions of results for a similar field in the Small Magellanic Cloud (SMC) suggest that the old stellar population of the SMC may have a slightly lower metal abundance than that of the LMC. The best available distance moduli for the Magellanic Clouds indicate a mean absolute visual magnitude M of +0.m5 ±0.2 for the RR Lyrae stars in these systems.

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