Is the SMC Bound to the LMC? The Hubble Space Telescope Proper Motion of the SMC

By N. Kallivayalil, R. P. van der Marel, Charles R. Alcock. 2006

214 citations recorded by the source corpus.

We present a measurement of the systemic proper motion of the Small Magellanic Cloud (SMC) made using the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST). We tracked the SMC's motion relative to four background QSOs over a baseline of approximately 2 yr. The measured proper motion is μW = -1.16 ± 0.18 mas yr-1, μN = -1.17 ± 0.18 mas yr-1. This is the best measurement yet of the SMC's proper motion. We combine this new result with our prior estimate of the proper motion of the Large Magellanic Cloud (LMC) from the same observing program to investigate the orbital evolution of both Clouds over the past 9 Gyr. The current relative velocity between the Clouds is 105 ± 42 km s-1. Our investigations of the past orbital motions of the Clouds in a simple model for the dark halo of the Milky Way imply that the Clouds could be unbound from each other. However, our data are also consistent with orbits in which the Clouds have been bound to each other for approximately a Hubble time. Smaller proper-motion errors and better understanding of the LMC and SMC masses would be required to constrain their past orbital history and their bound versus unbound nature unambiguously. The new proper-motion measurements should be sufficient to allow the construction of improved models for the origin and properties of the Magellanic Stream. In turn, this will provide new constraints on the properties of the Milky Way dark halo.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/1ded5e48bf3bcac92af75d6a9475a0f076fb2992

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Citations in the corpus

THE UNORTHODOX ORBITS OF SUBSTRUCTURE HALOS (2008, background): “Since the latest proper motion studies of the Magellanic Clouds seem to suggest that the Clouds are on their first pericentric passage (Kallivayalil et al 2006; Piatek et al 2007), this is a possibility to consider seriously when trying to puzzle out the significance of the motion of the satellites…”
THIRD-EPOCH MAGELLANIC CLOUD PROPER MOTIONS. I. HUBBLE SPACE TELESCOPE/WFC3 DATA AND ORBIT IMPLICATIONS (2013, background): “…of the Large and Small Magellanic Clouds made by our group with two epochs of Hubble Space Telescope’s (HST ) ACS High Resolution Camera (HRC) data (Kallivayalil et al. 2006a,b, hereafter K2 & K1), and confirmed by Piatek et al. (2008, hereafter P08), have revolutionized the field of Magellanic…”
THE SPACE MOTION OF LEO I: THE MASS OF THE MILKY WAY'S DARK MATTER HALO (2012, methodology): “The 11 13 These satellites are the Large and Small Magellanic Clouds (Kallivayalil et al. 2006a, 2006b; Piatek et al. 2008), Fornax (Piatek et al. 2007), Sculptor (Piatek et al. 2006), and Leo I (Sohn et al. 2013).”
THIRD-EPOCH MAGELLANIC CLOUD PROPER MOTIONS. II. THE LARGE MAGELLANIC CLOUD ROTATION FIELD IN THREE DIMENSIONS (2013, background): “The outlier rejection removes both foreground Milky Way stars, as well as stripped SMC stars that are seen in the direction of the LMC (estimated by O11 as ∼ 6% of their sample).”
Evolution of magnetic fields in galaxies and future observational tests with the Square Kilometre Array (2008, unknown): “Simulations indicate that the LMC may have passed through the plane of the Milky Way more than 2 Gyr ago, or that it is on its way to a first passage through the MW (Kallivayalil et al. 2006; Piatek et al. 2008, and references therein).”
Cool outflows in galaxies and their implications (2020, background): “This may be considered a lower limit since tidal stripping by the LMC and Milky Way, and ram-pressure forces associated with the fast (∼300 km s−1; Kallivayalil et al. 2006) motion of the SMC through the Milky Way halo, will promote the removal of any material that is outside of the host’s main body”
The Origin of the Magellanic Stream and Its Leading Arm (2007, methodology): “However, the orbit calculations using the new HST proper motions (Kallivayalil et al. 2006a,b; Piatek, Pryor, & Olszewski 2007) and an NFW MW potential by Besla et al. (2007) give past MC encounters at roughly 0.2, 3 and 6 Gyr ago (G. Belsa, private communication).”
AGE DETERMINATION OF SIX INTERMEDIATE-AGE SMALL MAGELLANIC CLOUD STAR CLUSTERS WITH HST/ACS (2008, unknown): “Possible orbits of the SMC, LMC, and MW have been modelled by several authors (e.g., Kallivayalil et al. 2006a/b; Bekki & Chiba 2005).”
The role of dwarf galaxy interactions in shaping the Magellanic System and implications for Magellanic Irregulars (2012, background): “These conclusions are further supported by recent proper motion measurements (Kallivayalil et al. 2006a, hereafter K1; Kallivayalil, van der Marel & Alcock 2006b, hereafter K2) which indicate that the LMC is moving ∼80 km s−1 faster than previously believed (Gardiner & Noguchi 1996).”
SPITZER SAGE SURVEY OF THE LARGE MAGELLANIC CLOUD. III. STAR FORMATION AND ∼1000 NEW CANDIDATE YOUNG STELLAR OBJECTS (2008, background): “Recent HST observations of proper motions in the LMC (Kallivayalil et al. 2006b) and Small Magellanic Cloud (SMC) (Kallivayalil et al. 2006a) suggest that the 3D velocities of the Clouds are much higher than previously thought, and the Clouds are on their first passage through the Milky Way (Besla…”
Small Dwarf Galaxies within Larger Dwarfs: Why Some Are Luminous while Most Go Dark (2008, background): “The proper motion of the SMC implies a velocity relative to the LMC of∼ 80 km s−1 at a separation of 23 kpc (Kallivayalil et al. 2006b).”
The Orbital Poles of Milky Way Satellite Galaxies: A Rotationally Supported Disk of Satellites (2008, methodology): “In this case the LMC-SMC system might be bound to theMilkyWay, even though they seem to have too high a velocity.”
The Milky Way’s Circular Velocity Curve to 60 kpc and an Estimate of the Dark Matter Halo Mass from the Kinematics of ~2400 SDSS Blue Horizontal-Branch Stars (2008, background): “However, recent results on the LMC (Kallivayalil et al. 2006; Besla et al. 2007) indicate that not even the Magellanic Clouds may have been bound to the Milky Way for long, posing a potential conceptual problems for the use of satellite dynamics.”
Local-Group tests of dark-matter concordance cosmology - Towards a new paradigm for structure formation (2010, background): “The LMC and SMC are excluded, as is Sagittarius because it is currently experiencing significant tidal disturbance.”
GASS: THE PARKES GALACTIC ALL-SKY SURVEY. I. SURVEY DESCRIPTION, GOALS, AND INITIAL DATA RELEASE (2009, unknown): “…which is close to the interaction region predicted in older models (e.g., Connors et al. 2006; Yoshizawa & Noguchi 2003) of the Magellanic System but somewhat surprising given the revised proper motions for the Large and Small Magellanic Clouds (van der Marel et al. 2002; Kallivayalil et al. 2006).”