scholarly journals Gaia view of a stellar sub-structure in front of the Small Magellanic Cloud

2020 ◽  
Vol 500 (3) ◽  
pp. 2757-2776
Author(s):  
Abinaya O Omkumar ◽  
Smitha Subramanian ◽  
Florian Niederhofer ◽  
Jonathan Diaz ◽  
Maria-Rosa L Cioni ◽  
...  
Keyword(s):  
Stellar Population ◽  
Tangential Velocity ◽  
Magellanic Cloud ◽  
Stellar Structure ◽  
Main Body ◽  
Small Magellanic Cloud ◽  
North West ◽  
The North ◽  
Spatial Coverage ◽  
Red Clump

ABSTRACT Recent observational studies identified a foreground stellar sub-structure traced by red clump (RC) stars (∼12 kpc in front of the main body) in the eastern regions of the Small Magellanic Cloud (SMC) and suggested that it formed during the formation of the Magellanic Bridge (MB), due to the tidal interaction of the Magellanic Clouds. Previous studies investigated this feature only up to 4${_{.}^{\circ}}$0 from the centre of the SMC due to the limited spatial coverage of the data and hence could not find a physical connection with the MB. To determine the spatial extent and properties of this foreground population, we analysed data from the Gaia Data Release 2 (DR2) of a ∼314 deg2 region centred on the SMC, which cover the entire SMC and a significant portion of the MB. We find that the foreground population is present only between 2${_{.}^{\circ}}$5 to ∼5°–6° from the centre of the SMC in the eastern regions, towards the MB and hence does not fully overlap with the MB in the plane of the sky. The foreground stellar population is found to be kinematically distinct from the stellar population of the main body with ∼35 km s−1 slower tangential velocity and moving to the north-west relative to the main body. Though the observed properties are not fully consistent with the simulations, a comparison indicates that the foreground stellar structure is most likely a tidally stripped counterpart of the gaseous MB and might have formed from the inner disc (dominated by stars) of the SMC. A chemical and 3D kinematic study of the RC stars along with improved simulations, including both tidal and hydro-dynamical effects, are required to understand the offset between the foreground structure and MB.

scholarly journals Presence of red giant population in the foreground stellar sub-structure of the Small Magellanic Cloud

2021 ◽  
Author(s):  
Dizna James ◽  
Smitha Subramanian ◽  
Abinaya O Omkumar ◽  
Adhya Mary ◽  
Kenji Bekki ◽  
...  
Keyword(s):  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Eastern Region ◽  
Main Body ◽  
Small Magellanic Cloud ◽  
Similar Distance ◽  
Red Clump ◽  
Red Giant ◽  
Astrometric Data ◽  
Recent Epoch

Abstract The eastern region of the Small Magellanic Cloud (SMC) is found to have a foreground stellar sub-structure, which is identified as a distance bimodality (∼ 12 kpc apart) in the previous studies using Red Clump (RC) stars. Interestingly, studies of Red Giant Branch (RGB) stars in the eastern SMC indicate a bimodal radial velocity (RV) distribution. In this study, we investigate the connection between these two bimodal distributions to better understand the nature and origin of the foreground stellar sub-structure in the eastern SMC. We use the Gaia EDR3 astrometric data and archival RV data of RGB stars for this study. We found a bimodal RV distribution of RGB stars (separated by ∼ 35–45 km s−1) in the eastern and south-western (SW) outer regions. The observed proper motion values of the lower and higher RV RGB components in the eastern regions are similar to those of the foreground and main-body RC stars respectively. This suggests that the two RGB populations in the eastern region are separated by a similar distance as those of the RC stars, and the RGB stars in the lower RV component are part of the foreground sub-structure. Based on the differences in the distance and RV of the two components, we estimated an approximate time of formation of this sub-structure as 307 ± 65 Myr ago. This is comparable with the values predicted by simulations for the recent epoch of tidal interaction between the Magellanic Clouds. Comparison of the observed properties of RGB stars, in the outer SW region, with N-body simulations shows that the higher RV component in the SW region is at a farther distance than the main body, indicating the presence of a stellar Counter-Bridge in the SW region of the SMC.

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.

AN HISTORIC GEOLOGY OF THE GIPPSLAND BASIN

1970 ◽  
Vol 10 (1) ◽  
pp. 70
Author(s):  
L. C. P. Wooldridge ◽  
W. G. Hill
Keyword(s):  
Oil And Gas ◽  
Flood Plain ◽  
Main Body ◽  
Deltaic Plain ◽  
North West ◽  
The North ◽  
Channel Belt ◽  
Muddy Sediments ◽  
Gippsland Basin ◽  
Regressive Phase

The Mesozoic and Tertiary rocks of the Gippsland Basin form a simple natural sequence as the deposits of a main regressive - transgressive cycle, followed by a regressive phase of lesser magnitude.After a period of early Mesozoic erosion in Gippsland, a river flowing from the north-west built extensive deposits which drove the sea back well beyond the present coast line. Strzelecki Formation is the name applied to the flood-plain sediments of this period. The channel belt deposits have been given various names and of these the Childers Formation appears to be the most valid. However, with the deltaic plain deposits, it can be regarded as forming a part of the Latrobe Valley Complex.About the end of Mesozoic time the sea began to transgress, also at this time there was some vulcanism in the western part of the basin. As transgression proceeded, the delta became digitate in form, similar to today's Mississippi delta. Silty and muddy sediments accumulated beyond the distributaries and between them, whilst the distributaries were areas of dominantly sand desposition. Marine agencies reworked some of the sand to form beaches and occasional barrier islands.As the sea transgressed the prodelta silty muds (Lakes Entrance Formation), covered the submerged distributaries and these in turn became covered by the cleaner water calcareous deposits of the Lower Gippsland Limestone. Meanwhile onshore, the flood-plain and earlier channel-belt deposits became overlain by later channel-belt deposits, and then by deltaic plain deposits with abundant coal. Transgression reached its zenith, probably during Miocene time, and a final regressive phase culminated in the situation as we see it today.The formation water in the main body of the Latrobe Valley complex is very fresh, and calculations show a static situation for both the Latrobe Valley and the contiguous glauconitic sandstone member, and thus the existence of down-dip escape is most unlikely. The oil at Lakes Entrance has not been flushed down-dip, rather it has moved up-dip.It follows from a consideration of the depositional history in Gippsland that producing structures at the top Latrobe Valley level are basically stratigraphic traps. They lie along ancient distributary channel trends and are flanked by contemporaneous muddy facies. Separate closures along the trends have been brought about by the development of saddles due to differential compaction and probably normal faulting at depth.The oil and gas pools today are more or less at their greatest depth of burial. An association is obvious between depth and hydrocarbon content for the top Latrobe Valley pools. A progression is noted from dry gas at Golden Beach (2,000') to a thick oil i Halibut (8,000'). Coal rank increases with depth. It is concluded that coal is the main hydrocarbon source in Gippsland. Thus all the Latrobe Valley section is prospective. The top Latrobe Valley horizon is probably the most productive to date because it has very effective cappingBarracouta 1, intersected a barrier island sand. There is likely to be more of these parallel to ancient shorelines. They could prove productive.

scholarly journals The Relation Between Field Massive Stars and Clusters

2007 ◽  
Vol 3 (S246) ◽  
pp. 65-66
Author(s):  
M. S. Oey ◽  
N. L. King ◽  
J. Wm. Parker ◽  
J. B. Lamb
Keyword(s):  
Small Groups ◽  
Stellar Population ◽  
Massive Stars ◽  
Magellanic Cloud ◽  
Small Magellanic Cloud ◽  
Multiple Origins ◽  
External Galaxies ◽  
Runaway Stars ◽  
Massive Field

AbstractMassive “field” stars are those that appear in apparent isolation, in contrast to those in clusters. Whereas cluster stars are formed together in large aggregates, simultaneously, field stars have multiple origins. Some massive field stars may be the “tip of the iceberg” on small groups of physically associated stars, while others appear to be “runaway” stars that are dynamically ejected from clusters. What is the intrinsic relation between clusters and field stars, and what is the faction of runaway stars? Since massive stars are the most luminous stellar population, their demographics are accessible in the nearest external galaxies. We present our current efforts to understand these issues for the Small Magellanic Cloud.

scholarly journals The VMC survey – XLI. Stellar proper motions within the Small Magellanic Cloud

2021 ◽  
Vol 502 (2) ◽  
pp. 2859-2878
Author(s):  
Florian Niederhofer ◽  
Maria-Rosa L Cioni ◽  
Stefano Rubele ◽  
Thomas Schmidt ◽  
Jonathan D Diaz ◽  
...  
Keyword(s):  
Near Infrared ◽  
Magellanic Cloud ◽  
Mass Motion ◽  
Small Magellanic Cloud ◽  
Proper Motions ◽  
Spatially Resolved ◽  
Infrared Telescope ◽  
The North ◽  
The Galaxy ◽  
Older Populations

ABSTRACT We used data from the near-infrared Visible and Infrared Telescope for Astronomy (VISTA) survey of the Magellanic Cloud system (VMC) to measure proper motions (PMs) of stars within the Small Magellanic Cloud (SMC). The data analysed in this study comprise 26 VMC tiles, covering a total contiguous area on the sky of ∼40 deg2. Using multi-epoch observations in the Ks band over time baselines between 13 and 38 months, we calculated absolute PMs with respect to ∼130 000 background galaxies. We selected a sample of ∼2160 000 likely SMC member stars to model the centre-of-mass motion of the galaxy. The results found for three different choices of the SMC centre are in good agreement with recent space-based measurements. Using the systemic motion of the SMC, we constructed spatially resolved residual PM maps and analysed for the first time the internal kinematics of the intermediate-age/old and young stellar populations separately. We found outward motions that point either towards a stretching of the galaxy or stripping of its outer regions. Stellar motions towards the North might be related to the ‘Counter Bridge’ behind the SMC. The young populations show larger PMs in the region of the SMC Wing, towards the young Magellanic Bridge. In the older populations, we further detected a coordinated motion of stars away from the SMC in the direction of the Old Bridge as well as a stream towards the SMC.

scholarly journals Nature of a shell of young stars in the outskirts of the Small Magellanic Cloud

2019 ◽  
Vol 631 ◽  
pp. A98 ◽  
Author(s):  
David Martínez-Delgado ◽  
Anna Katherina Vivas ◽  
Eva K. Grebel ◽  
Carme Gallart ◽  
Adriano Pieres ◽  
...  
Keyword(s):  
Stellar System ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Young Stars ◽  
Optical Data ◽  
Small Magellanic Cloud ◽  
Stellar Content ◽  
North East ◽  
The North ◽  
Spiral Arm

Context. Understanding the evolutionary history of the Magellanic Clouds requires an in-depth exploration and characterization of the stellar content in their outer regions, which ultimately are key to tracing the epochs and nature of past interactions. Aims. We present new deep images of a shell-like overdensity of stars in the outskirts of the Small Magellanic Cloud (SMC). The shell, also detected in photographic plates dating back to the fifties, is located at ∼1.9° from the center of the SMC in the north-east direction. Methods. The structure and stellar content of this feature were studied with multiband, optical data from the Survey of the MAgellanic Stellar History (SMASH) carried out with the Dark Energy Camera on the Blanco Telescope at Cerro Tololo Inter-American Observatory. We also investigate the kinematic of the stars in the shell using the Gaia Data Release 2. Results. The shell is composed of a young population with an age ∼150 Myr, with no contribution from an old population. Thus, it is hard to explain its origin as the remnant of a tidally disrupted stellar system. The spatial distribution of the young main-sequence stars shows a rich sub-structure, with a spiral arm-like feature emanating from the main shell and a separated small arc of young stars close to the globular cluster NGC 362. We find that the absolute g-band magnitude of the shell is Mg, shell = −10.78 ± 0.02, with a surface brightness of μg, shell = 25.81 ± 0.01 mag arcsec−2. Conclusion. We have not found any evidence that this feature is of tidal origin or a bright part of a spiral arm-like structure. Instead, we suggest that the shell formed in a recent star formation event, likely triggered by an interaction with the Large Magellanic Cloud and or the Milky Way, ∼150 Myr ago.

New insights into reservoir sand provenance in the Exmouth Plateau and Browse Basin

2011 ◽  
Vol 51 (2) ◽  
pp. 715 ◽  
Author(s):  
Peter Southgate ◽  
Keith Sircombe ◽  
Christopher Lewis
Keyword(s):  
Sediment Transport ◽  
Transport Pathways ◽  
North West ◽  
The Past ◽  
The North ◽  
Geological Surveys ◽  
Source Regions ◽  
Provenance Areas ◽  
Spatial Coverage ◽  
Sand Provenance

A pilot study to determine if zircons present in reservoir facies of the North West Shelf can be used to identify provenance and sediment transport pathways has analysed samples from three wells: Guardian–1 and Hijinx–1 (Carnarvon Basin), and Burnside–1 (Browse Basin). Operating companies Chevron, Santos and Hess collected 3–5 kg of cuttings from sandstone bodies intersected in the three wells. Samples were sent to Geoscience Australia for zircon separation and analysis at the Geochronology Laboratory on a sensitive high-resolution ion microprobe (SHRIMP). To provide a statistically meaningful representation of ages in each sample, 70–80 grains were randomly selected for analysis. During the past 20 years, Geoscience Australia and the state geological surveys of WA, NT, Queensland and SA, together with the ANU, UWA and Curtin University, have analysed zircons found in igneous and sedimentary rocks that outcrop in WA and central Australia. This analysis has been done to determine the ages of emplacement, extrusion or maximum depositional ages. This dataset permits the ages of potential onshore provenance areas to be differentiated; hence, correlations can be made between zircons contained within the transported sands and their potential source regions from onshore Australia. In this extended abstract, the spectrum of ages in each sample will be shown, and potential provenance and sediment transport pathways will be discussed. The abstract concludes with the outline of a 2–3 year project to obtain a dataset that will provide a regional stratigraphic and spatial coverage of the North West Shelf for provenance studies.

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