Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userKinematic complexity around NGC$,$419: resolving the proper motion of the cluster, the Small Magellanic Cloud and the Magellanic Bridge
72
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We present $it{Hubble}$ $it{Space}$ $it{Telescope}$ proper motions in the direction of the star cluster NGC$,$419 in the Small Magellanic Cloud. Because of the high precision of our measurements, for the first time it is possible to resolve the complex kinematics of the stellar populations located in the field, even along the tangential direction. In fact, the proper motions we measured allow us to separate cluster stars, which move on average with ($mu_{alpha}cosdelta^{rm NGC,419}, mu_{delta}^{rm NGC,419}$) = ($+0.878pm0.055$, $-1.246pm0.048$) mas yr$^{-1}$, from those of the Small Magellanic Cloud and those belonging to a third kinematic feature that we recognise as part of the Magellanic Bridge. Resolving such a kinematic complexity enables the construction of decontaminated colour-magnitude diagrams, as well as the measurement of the absolute proper motion of the three separate components. Our study therefore sets the first steps towards the possibility of dynamically investigating the Magellanic system by exploiting the resolved kinematics of its stellar clusters.
rate research
Read More
We present a new measurement of the systemic proper motion of the Small Magellanic Cloud (SMC), based on an expanded set of 30 fields containing background quasars and spanning a $sim$3 year baseline, using the textit{Hubble Space Telescope} (textit{HST}) Wide Field Camera 3. Combining this data with our previous 5 textit{HST} fields, and an additional 8 measurements from the textit{Gaia}-Tycho Astrometric Solution Catalog, brings us to a total of 43 SMC fields. We measure a systemic motion of $mu_{W}$ = $-0.82$ $pm$ 0.02 (random) $pm$ 0.10 (systematic) mas yr$^{-1}$ and $mu_{N}$ = $-1.21$ $pm$ 0.01 (random) $pm$ 0.03 (systematic) mas yr$^{-1}$. After subtraction of the systemic motion, we find little evidence for rotation, but find an ordered mean motion radially away from the SMC in the outer regions of the galaxy, indicating that the SMC is in the process of tidal disruption. We model the past interactions of the Clouds with each other based on the measured present-day relative velocity between them of $103 pm 26$ km s$^{-1}$. We find that in 97% of our considered cases, the Clouds experienced a direct collision $147 pm 33$ Myr ago, with a mean impact parameter of $7.5 pm 2.5$ kpc.
The Magellanic Clouds are a nearby pair of interacting dwarf galaxies and satellites of the Milky Way. Studying their kinematic properties is essential to understanding their origin and dynamical evolution. They have prominent tidal features and the kinematics of these features can give hints about the formation of tidal dwarfs, galaxy merging and the stripping of gas. In addition they are an example of dwarf galaxies that are in the process of merging with a massive galaxy. The goal of this study is to investigate the kinematics of the Magellanic Bridge, a tidal feature connecting the Magellanic Clouds, using stellar proper motions to understand their most recent interaction. We calculated proper motions based on multi-epoch $K_{s}$-band aperture photometry, which were obtained with the Visible and Infrared Survey Telescope for Astronomy (VISTA), spanning a time of 1-3 yr, and we compared them with $Gaia$ Data Release 2 (DR2) proper motions. We tested two methods for removing Milky Way foreground stars using $Gaia$~DR2 parallaxes in combination with VISTA photometry or using distances based on Bayesian inference. We obtained proper motions for a total of 576,411 unique sources over an area of $23$ deg$^{2}$ covering the Magellanic Bridge including mainly Milky Way foreground stars, background galaxies, and a small population of possible Magellanic Bridge stars ($<$15,000). The first proper motion measurement of the Magellanic Bridge centre is $1.80pm0.25$ mas yr$^{-1}$ in right ascension and $-0.72pm0.13$ mas yr$^{-1}$ in declination. The proper motion measurements confirm a flow motion from the Small to the Large Magellanic Cloud. This flow can now be measured all across the entire length of the Magellanic Bridge. Our measurements indicate that the Magellanic Bridge is stretching.
The Magellanic System (MS) encompasses the nearest neighbors of the Milky Way, the Large (LMC) and Small (SMC) Magellanic Clouds, and the Magellanic Bridge (MBR). This system contains a diverse sample of star clusters. Their parameters, such as the spatial distribution, chemical composition and age distribution yield important information about the formation scenario of the whole Magellanic System. Using deep photometric maps compiled in the fourth phase of the Optical Gravitational Lensing Experiment (OGLE-IV) we present the most complete catalog of star clusters in the Magellanic System ever constructed from homogeneous, long time-scale photometric data. In this second paper of the series, we show the collection of star clusters found in the area of about 360 square degrees in the MBR and in the outer regions of the SMC. Our sample contains 198 visually identified star cluster candidates, 75 of which were not listed in any of the previously published catalogs. The new discoveries are mainly young small open clusters or clusters similar to associations.
We used data from the near-infrared 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 deg$^2$. 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 ~2,160,000 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.
We present the first detailed kinematic analysis of the proper motions (PMs) of stars in the Magellanic Bridge, from both the textit{Gaia} Data Release 2 catalog and from textit{Hubble Space Telescope} Advanced Camera for Surveys data. For the textit{Gaia} data, we identify and select two populations of stars in the Bridge region, young main sequence (MS) and red giant stars. The spatial locations of the stars are compared against the known H {small I} gas structure, finding a correlation between the MS stars and the H {small I} gas. In the textit{Hubble Space Telescope} fields our signal comes mainly from an older MS and turn-off population, and the proper motion baselines range between $sim 4$ and 13 years. The PMs of these different populations are found to be consistent with each other, as well as across the two telescopes. When the absolute motion of the Small Magellanic Cloud is subtracted out, the residual Bridge motions display a general pattern of pointing away from the Small Magellanic Cloud towards the Large Magellanic Cloud. We compare in detail the kinematics of the stellar samples against numerical simulations of the interactions between the Small and Large Magellanic Clouds, and find general agreement between the kinematics of the observed populations and a simulation in which the Clouds have undergone a recent direct collision.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
