scholarly journals The intrinsic reddening of the Magellanic Clouds as traced by background galaxies – I. The bar and outskirts of the Small Magellanic Cloud

2019 ◽  
Vol 489 (3) ◽  
pp. 3200-3217
Author(s):  
Cameron P M Bell ◽  
Maria-Rosa L Cioni ◽  
A H Wright ◽  
Stefano Rubele ◽  
David L Nidever ◽  
...  
Keyword(s):  
Near Infrared ◽  
Broad Band ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Spectral Energy ◽  
Small Magellanic Cloud ◽  
Energy Distributions ◽  
Stellar Objects ◽  
Quasi Stellar Objects ◽  
Low Levels

ABSTRACT We present a method to map the total intrinsic reddening of a foreground extinguishing medium via the analysis of spectral energy distributions (SEDs) of background galaxies. In this pilot study, we implement this technique in two distinct regions of the Small Magellanic Cloud (SMC) – the bar and the southern outskirts – using a combination of optical and near-infrared ugrizYJKs broad-band imaging. We adopt the lephare χ2-minimization SED-fitting routine and various samples of galaxies and/or quasi-stellar objects to investigate the intrinsic reddening. We find that only when we construct reddening maps using objects classified as galaxies with low levels of intrinsic reddening (i.e. ellipticals/lenticulars and early-type spirals), the resultant maps are consistent with previous literature determinations, i.e. the intrinsic reddening of the SMC bar is higher than that in the outer environs. We employ two sets of galaxy templates – one theoretical and one empirical – to test for template dependences in the resulting reddening maps and find that the theoretical templates imply systematically higher reddening values by up to 0.20 mag in E(B − V). A comparison with previous reddening maps, based on the stellar components of the SMC, typically shows reasonable agreement. There is, however, significant variation amongst the literature reddening maps as to the level of intrinsic reddening associated with the bar. Thus, it is difficult to unambiguously state that instances of significant discrepancies are the result of appreciable levels of dust not accounted for in some literature reddening maps or whether they reflect issues with our adopted methodology.

scholarly journals Massive young stellar objects in the N 66/NGC 346 region of the SMC

2018 ◽  
Vol 615 ◽  
pp. A121 ◽  
Author(s):  
M. Rubio ◽  
R. H. Barbá ◽  
V. M. Kalari
Keyword(s):  
Star Formation ◽  
Magellanic Cloud ◽  
Young Stellar Objects ◽  
High Mass ◽  
Spectral Energy ◽  
Mass Star ◽  
Spectral Features ◽  
Small Magellanic Cloud ◽  
Energy Distributions ◽  
Stellar Objects

We present HK spectra of three sources located in the N 66 region of the Small Magellanic Cloud. The sources display prominent stellar Brγ and extended H2 emission, and exhibit infrared excesses at λ > 2 μm. Based on their spectral features, and photometric spectral energy distributions, we suggest that these sources are massive young stellar objects. The findings are interpreted as evidence of on-going high mass star formation in N 66.

scholarly journals The intrinsic reddening of the Magellanic Clouds as traced by background galaxies – II. The Small Magellanic Cloud

2020 ◽  
Vol 499 (1) ◽  
pp. 993-1004
Author(s):  
Cameron P M Bell ◽  
Maria-Rosa L Cioni ◽  
A H Wright ◽  
Stefano Rubele ◽  
David L Nidever ◽  
...  
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Dust Emission ◽  
Magellanic Cloud ◽  
Spectral Energy ◽  
Main Body ◽  
Small Magellanic Cloud ◽  
Full Sample ◽  
Low Levels ◽  
Biased Samples

ABSTRACT We present a map of the total intrinsic reddening across ≃34 deg2 of the Small Magellanic Cloud (SMC) derived using optical (ugriz) and near-infrared (IR; YJKs) spectral energy distributions (SEDs) of background galaxies. The reddening map is created using a subsample of 29 274 galaxies with low levels of intrinsic reddening based on the lephare χ2 minimization SED-fitting routine. We find statistically significant enhanced levels of reddening associated with the main body of the SMC compared with regions in the outskirts [ΔE(B − V) ≃ 0.3 mag]. A comparison with literature reddening maps of the SMC shows that, after correcting for differences in the volume of the SMC sampled, there is good agreement between our results and maps created using young stars. In contrast, we find significant discrepancies between our results and maps created using old stars or based on longer wavelength far-IR dust emission that could stem from biased samples in the former and uncertainties in the far-IR emissivity and the optical properties of the dust grains in the latter. This study represents one of the first large-scale categorizations of extragalactic sources behind the SMC and as such we provide the lephare outputs for our full sample of ∼500 000 sources.

scholarly journals UVIT-HST-Gaia-VISTA study of KRON 3 in the Small Magellanic Cloud: A cluster with an extended red clump in UV

2021 ◽  
Author(s):  
P K Nayak ◽  
A Subramaniam ◽  
S Subramanian ◽  
S Sahu ◽  
C Mondal ◽  
...  
Keyword(s):  
Near Infrared ◽  
Spectral Energy Distribution ◽  
Variable Mass ◽  
Intrinsic Property ◽  
Small Variation ◽  
Magellanic Cloud ◽  
Spectral Energy ◽  
Small Range ◽  
Small Magellanic Cloud ◽  
Red Clump

Abstract We have demonstrated the advantage of combining multi-wavelength observations, from the ultraviolet (UV) to near-infrared, to study Kron 3, a massive star cluster in the Small Magellanic Cloud. We have estimated the radius of the cluster Kron 3 to be 2${_{.}^{\prime}}$0 and for the first time, we report the identification of NUV-bright red clump (RC) stars and the extension of the RC in colour and magnitude in the NUV versus (NUV−optical) colour-magnitude diagram (CMD). We found that extension of the RC is an intrinsic property of the cluster and it is not due to contamination of field stars or differential reddening across the field. We studied the spectral energy distribution of the RC stars, and estimated a small range in temperature ∼5000–5500 K, luminosity ∼60–90 L⊙ and radius ∼8.0–11.0 R⊙ supporting their RC nature. The range of UV magnitudes amongst the RC stars (∼23.3 to 24.8 mag) is likely caused by the combined effects of variable mass loss, variation in initial helium abundance (Yini = 0.23 to 0.28), and a small variation in age (6.5-7.5 Gyr) and metallicity ([Fe/H] = −1.5 to −1.3). Spectroscopic follow-up observations of RC stars in Kron 3 are necessary to confirm the cause of the extended RC.

scholarly journals A near-infrared VISTA of the Small Magellanic Cloud

2018 ◽  
Vol 14 (S344) ◽  
pp. 53-56
Author(s):  
Maria-Rosa L. Cioni ◽  
Florian Niederhofer ◽  
Stefano Rubele ◽  
Ning-Chen Sun
Keyword(s):  
Near Infrared ◽  
Stellar Populations ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Level Of Detail ◽  
Star Formation History ◽  
Main Body ◽  
Small Magellanic Cloud ◽  
Formation History ◽  
The Galaxy

AbstractVISTA observed the Small Magellanic Cloud (SMC), as part of the VISTA survey of the Magellanic Clouds system (VMC), for six years (2010–2016). The acquired multi-epoch YJKs images have allowed us to probe the stellar populations to an exceptional level of detail across an unprecedented wide area in the near-infrared. This contribution highlights the most recent VMC results obtained on the SMC focusing, in particular, on the clustering of young stellar populations, on the proper motion of stars in the main body of the galaxy and on the spatial distribution of the star formation history.

scholarly journals Characterising the Protostellar Population of the Magellanic Clouds with VLT/SINFONI

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
Jacob Ward ◽  
Joana Oliveira ◽  
Jacco van Loon ◽  
Marta Sewilo
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Emission Lines ◽  
Young Stellar Objects ◽  
Small Magellanic Cloud ◽  
Stellar Objects ◽  
Accretion Rates

AbstractAt distances of ~50 kpc and ~60 kpc for the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) respectively the Magellanic Clouds present us with a unique opportunity to study star formation in environments outside our own galaxy. Through Spitzer and Herschel photometry and spectroscopy, samples of Young Stellar Objects (YSOs) have been selected and spectroscpically confirmed in the Magellanic Clouds. Here we present some of the key results of our SINFONI K-band observations towards massive YSOs in the Magellanic Clouds. We resolve a number of Spitzer sources into multiple, previously unresolved, components and our analysis of emission lines suggest higher accretion rates and different disc properties compared with massive YSOs in the Milky Way.

scholarly journals A near infrared variable star survey in the Magellanic Clouds: The Small Magellanic Cloud data

2018 ◽  
Author(s):  
Yoshifusa Ita ◽  
Noriyuki Matsunaga ◽  
Toshihiko Tanabé ◽  
Yoshikazu Nakada ◽  
Daisuke Kato ◽  
...  
Keyword(s):  
Near Infrared ◽  
Variable Star ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Small Magellanic Cloud ◽  
Cloud Data

scholarly journals The VMC survey – XXXIX. Mapping metallicity trends in the Small Magellanic Cloud using near-infrared passbands

2020 ◽  
Vol 497 (3) ◽  
pp. 3746-3760
Author(s):  
Samyaday Choudhury ◽  
Richard de Grijs ◽  
Stefano Rubele ◽  
Kenji Bekki ◽  
Maria-Rosa L Cioni ◽  
...  
Keyword(s):  
Near Infrared ◽  
High Spatial Resolution ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Galactic Centre ◽  
Small Magellanic Cloud ◽  
The West ◽  
Tidal Interactions ◽  
Red Giant ◽  
Metallicity Distribution

ABSTRACT We have derived high-spatial-resolution metallicity maps covering ∼42 deg2 across the Small Magellanic Cloud (SMC) in an attempt to understand its metallicity distribution and gradients up to a radius of ∼4○. Using the near-infrared VISTA Survey of the Magellanic Clouds, our data cover a thrice larger area compared with previous studies. We identify red giant branch (RGB) stars in spatially distinct Y, (Y − Ks) colour–magnitude diagrams. In any of our selected subregions, the RGB slope is used as an indicator of the average metallicity, based on calibration to metallicity using spectroscopic data. The metallicity distribution across the SMC is unimodal and can be fitted by a Gaussian distribution with a peak at [Fe/H] = −0.97 dex (σ[Fe/H] = 0.05 dex). We find evidence of a shallow gradient in metallicity (−0.031 ± 0.005 dex deg−1) from the Galactic Centre to radii of 2○–2${_{.}^{\circ}}$5, followed by a flat metallicity trend from ∼3${_{.}^{\circ}}$5 to 4○. We find that the SMC’s metallicity gradient is radially asymmetric. It is flatter towards the east than to the west, hinting at mixing and/or distortion of the spatial metallicity distribution (within the inner 3○), presumably caused by tidal interactions between the Magellanic Clouds.

scholarly journals Observational Studies of the Structure of Active Galactic Nuclei and QSOs

1989 ◽  
Vol 134 ◽  
pp. 273-283
Author(s):  
J. S. Miller
Keyword(s):  
Galactic Nuclei ◽  
Active Galaxies ◽  
Spectral Energy ◽  
Energy Distributions ◽  
Stellar Objects ◽  
Quasi Stellar Objects ◽  
Physical Information ◽  
To Come ◽  
Polarization Of Light ◽  
Insight Into

Direct observational information on the structures of the central objects of active galaxies and quasi-stellar objects is hard to come by. Most of what we believe about these regions is inferred from data concerning the emission line spectra, the spectral energy distributions of the featureless continuum, and the luminosities and variability of the active nucleus. Data on the polarization of light from active galaxies, especially spectropolarimetric data which distinguishes between lines and continua, can offer additional insight into the nature of the central object, to some extent more direct information insofar as it can provide geometrical as well as physical information.

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