The recent star-formation history of the Large and Small Magellanic Clouds

Indu, G.; Subramaniam, Annapurni

doi:10.1051/0004-6361/201117298

Cited by 45 publications

(46 citation statements)

References 34 publications

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“…The mean value obtained from our study is 0.096 ± 0.08 mag. This is similar to the value obtained from the study of stellar population of similar age as that of Cepheids (Indu & Subramaniam 2011).…”

Section: Reddening Mapsupporting

confidence: 90%

“…3, we can see that the central regions have a higher reddening than the surrounding regions. This result is consistent with the reddening map (Indu & Subramaniam 2011) regions with high reddening coincide in the reddening maps obtained using different tracers, the values are different. The mean value obtained from our study is 0.096 ± 0.08 mag.…”

Section: Reddening Mapsupporting

confidence: 90%

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Disk of the Small Magellanic Cloud as traced by Cepheids

Subramanian

Subramaniam

2015

A&A

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Context. The structure and evolution of the disk of the Small Magellanic Cloud (SMC) are traced by studying the Cepheids. Aims. We aim to estimate the orientation measurements of the disk, such as the inclination, i, and the position angle of the line of nodes (PA lon ), φ, and the depth of the disk. We also derive the age of the Cepheids and hence the age distribution of the SMC Cepheids. Methods. We used the V and I band photometric data of the fundamental and first-overtone Cepheids from the Optical Gravitational Lensing Experiment survey. The period-luminosity (PL) relations were used to estimate the relative distance and reddening of each Cepheid. The right ascension, declination, and relative distance from the centroid of each Cepheid were converted into x, y, and z Cartesian coordinates. A weighted least-square plane fitting method was then applied to estimate the structural parameters. The lineof-sight depth and then the orientation corrected depth or thickness of the disk were estimated from the relative distance measurements. The period-age-colour relation of Cepheids were used to derive the age of the Cepheids. Results. A break in the PL relations of both the fundamental mode and first-overtone Cepheids at P ∼ 2.95 days and P ∼ 1 day are observed. An inclination of 64.• 4 ± 0.• 7 and a PA lon = 155.• 3 ± 6.• 3 are obtained from the full sample. A reddening map of the SMC disk is also presented. The orientation-corrected depth or thickness of the SMC disk is found to be 1.76 ± 0.6 kpc. The scale height is estimated to be 0.82 ± 0.3 kpc. The age distribution of Cepheids matches the SMC cluster age distribution. Conclusions. The radial variation of the disk parameters mildly indicate structures and disturbances in the inner SMC (0.5 < r < 2.5 degree). Some of the Cepheids found in front of the fitted plane in the eastern regions are possibly the youngest tidally stripped counterpart of the H i gas of the Magellanic Bridge. The Cepheids behind the fitted plane are most likely the population in the Counter Bridge predicted in recent numerical simulations. Different scenarios for the origin of the extra-planar Cepheids are also discussed.

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Section: Reddening Mapsupporting

confidence: 90%

Section: Reddening Mapsupporting

confidence: 90%

Disk of the Small Magellanic Cloud as traced by Cepheids

Subramanian

Subramaniam

2015

A&A

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“…The leading edge is characterized by multiple HI velocity components, the faster among them being possibly extraplanar (Luks & Rohlfs 1992;Nidever et al 2008Nidever et al , 2010, which point towards a strong interaction between the LMC's ISM and the ambient material it passes through. HI column and star formation are both more concentrated in the southeastern portion of the LMC disk; an entire "supershell" of denser gas and rapid star formation exists at the leading edge of the LMC disk, perhaps due to a bow-shock (de Boer et al 1998;Murali 2000), and regions devoid of gas exist despite the presence of young stars (Indu & Subramaniam 2011). Likewise the MS and LA are likely significantly altered by this ambient medium.…”

Section: Introductionmentioning

confidence: 99%

Ram Pressure Stripping of the Large Magellanic Cloud’s Disk as a Probe of the Milky Way’s Circumgalactic Medium

Salem

Besla

Bryan

et al. 2015

ApJ

163

228

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Recent observations have constrained the orbit and structure of the Large Magellanic Cloud (LMC), implying a well-constrained pericentric passage about the Milky Way (MW) ∼ 50 Myr ago. In this scenario, the LMC's gaseous disk has recently experienced stripping, suggesting the current extent of its HI disk directly probes the medium in which it is moving. From the observed stellar and HI distributions of the system we find evidence of a truncated gas profile along the windward "leading edge' of the LMC disk, despite a far more extended stellar component. We explore the implications of this ram pressure stripping signature, using both analytic prescriptions and full 3-dimensional hydrodynamic simulations of the LMC. Our simulations subject the system to a headwind whose velocity components correspond directly to the recent orbital history of the LMC. We vary the density of this headwind, using a variety of sampled parameters for a β-profile for a theoretical MW circumgalactic medium (CGM), comparing the resulting HI morphology directly to observations of the LMC HI and stellar components. This model can match the radial extent of the LMC's leading (windward) edge only in scenarios where the MW CGM density at pericentric passage is n p (R = 48.2 ± 5 kpc) = 1.1−.45 × 10 −4 cm −3 . The implied pericentric density proves insensitive to both the broader CGM structure and temperature profile, thus providing a model-independent constraint on the local gas density. This result imposes an important constraint on the density profile of the MW's CGM, and thus the total baryon content of the MW. From our work, assuming a β-profile valid to ∼ r vir , we infer a total diffuse CGM mass M (300 kpc) = 2.6 ± 1.4 × 10 10 M ⊙ or approximately 15% of a 10 12 M ⊙ MW's baryonic mass budget.

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“…The more massive Milky Way galaxy accrete the MCS and tidal forces and perhaps drag separate gas from the stellar bodies. Highsensitivity optical studies disclose even the faintest stellar populations of evolved stars and allow to search for evidence of the stellar-gas-feedback processes triggered by the interaction with the Milky Way halo and/or its gravitational field (Indu & Subramaniam 2011). Both stellar distributions are highly concentrated, so only a fraction also populate the Magellanic Bridge (Putman et al 2003;Irwin et al 1990).…”

Section: Introductionmentioning

confidence: 99%

The four leading arms of the Magellanic Cloud system

Venzmer¹,

Kerp²,

Kalberla³

2012

A&A

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Context. The Magellanic Cloud system (MCS) interacts via tidal and drag forces with the Milky Way galaxy. Aims. Using the Parkes Galactic All-Sky Survey (GASS) of atomic hydrogen we explore the role of drag on the evolution of the so-called Leading Arm (LA).Methods. We present a new image recognition algorithm that allows us to differentiate features within a 3D data cube (longitude, latitude, radial velocity) and to parameterize individual coherent structures. We compiled an Hi object catalog of LA objects within an area of 70 • × 85 • (1.6 sr) of the LA region. This catalog comprises information of location, column density, line width, shape and asymmetries of the individual LA objects above the 4-σ threshold of ΔT b 200 mK.Results. We present evidence of a fourth arm segment (LA4). For all LA objects we find an inverse correlation of velocities v GSR in Galactic Standard of Rest frame with Magellanic longitude. High-mass objects tend to have higher radial velocities than low-mass ones. About 1/4 of all LA objects can be characterized as head-tail (HT) structures. Conclusions. Using image recognition with objective criteria, it is feasible to isolate most of LA emission from the diffuse Milky Way Hi gas. Some blended gas components (we estimate 5%) escape detection, but we find a total gas content of the LA that is about 50% higher than previously assumed. These methods allow the deceleration of the LA clouds to be traced towards the Milky Way disk by drag forces. The derived velocity gradient strongly supports the assumption that the whole LA originates entirely in the Large Magellanic Cloud (LMC). LA4 is observed opposite to LA1, and we propose that both arms are related, spanning about 52 kpc in space. HT structures trace drag forces even at tens of kpc altitudes above the Milky Way disk.

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The recent star-formation history of the Large and Small Magellanic Clouds

Cited by 45 publications

References 34 publications

Disk of the Small Magellanic Cloud as traced by Cepheids

Disk of the Small Magellanic Cloud as traced by Cepheids

Ram Pressure Stripping of the Large Magellanic Cloud’s Disk as a Probe of the Milky Way’s Circumgalactic Medium

The four leading arms of the Magellanic Cloud system

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