THIRD-EPOCH MAGELLANIC CLOUD PROPER MOTIONS. I. HUBBLE SPACE TELESCOPE/WFC3 DATA AND ORBIT IMPLICATIONS

By N. Kallivayalil, R. P. van der Marel, G. Besla, Jay Anderson, Charles R. Alcock. 2013

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We present proper motions for the Large and Small Magellanic Clouds (LMC and SMC) based on three epochs of Hubble Space Telescope data, spanning a ∼7 yr baseline, and centered on fields with background QSOs. The first two epochs, the subject of past analyses, were obtained with ACS/HRC, and have been reanalyzed here. The new third epoch with WFC3/UVIS increases the time baseline and provides better control of systematics. The three-epoch data yield proper-motion random errors of only 1%–2% per field. For the LMC this is sufficient to constrain the internal proper-motion dynamics, as will be discussed in a separate paper. Here we focus on the implied center-of-mass proper motions: μW, LMC = −1.910 ± 0.020 mas yr−1, μN, LMC = 0.229 ± 0.047 mas yr−1, and μW, SMC = −0.772 ± 0.063 mas yr−1, μN, SMC = −1.117 ± 0.061 mas yr−1. We combine the results with a revised understanding of the solar motion in the Milky Way to derive Galactocentric velocities: vtot, LMC = 321 ± 24 km s−1 and vtot, SMC = 217 ± 26 km s−1. Our proper-motion uncertainties are now dominated by limitations in our understanding of the internal kinematics and geometry of the Clouds, and our velocity uncertainties are dominated by distance errors. Orbit calculations for the Clouds around the Milky Way allow a range of orbital periods, depending on the uncertain masses of the Milky Way and LMC. Periods ≲ 4 Gyr are ruled out, which poses a challenge for traditional Magellanic Stream models. First-infall orbits are preferred (as supported by other arguments as well) if one imposes the requirement that the LMC and SMC must have been a bound pair for at least several Gyr.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/f71ad2cd3235d096a4380acf96f8b64655df2507

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Citations in the corpus

Hunting for the Dark Matter Wake Induced by the Large Magellanic Cloud (2019, methodology): “Moreover, owing to dynamical friction, the orbital history of the LMC also strongly depends on its mass (Kallivayalil et al. 2013).”
The influence of Sagittarius and the Large Magellanic Cloud on the stellar disc of the Milky Way Galaxy (2017, methodology): “In addition to the Sgr dwarf, there is increasing evidence that the Magellanic Clouds are on their first infall onto the Milky Way (Besla et al. 2007; Kallivayalil et al. 2013).”
THIRD-EPOCH MAGELLANIC CLOUD PROPER MOTIONS. II. THE LARGE MAGELLANIC CLOUD ROTATION FIELD IN THREE DIMENSIONS (2013, methodology): “We recently presented a third epoch of HST PM data for 10 fields (Kallivayalil et al. 2013; hereafter Paper I), increasing the median time baseline to 7.1 years.”
BEASTS OF THE SOUTHERN WILD: DISCOVERY OF NINE ULTRA FAINT SATELLITES IN THE VICINITY OF THE MAGELLANIC CLOUDS (2015, methodology): “Kallivayalil et al. (2013)9.”
THE SPACE MOTION OF LEO I: THE MASS OF THE MILKY WAY'S DARK MATTER HALO (2012, background): “However, the revised value of the LMC’s Galactocentric velocity (Kallivayalil et al. 2013) places it on an orbit that is more bound than Leo I so long as Mvir,MW 7 × 1011 M .”
The RAVE survey : the Galactic escape speed and the mass of the Milky Way (2013, background): “…mass and the mass profile of the Galaxy is Article published by EDP Sciences A91, page 1 of 16 crucial for understanding and modeling the dynamic evolution of the MW satellite galaxies (e.g., Kallivayalil et al. 2013, for the Magellanic clouds) and the Local Group (van der Marel et al. 2012b,a).”
Evidence for an Intermediate-mass Milky Way from Gaia DR2 Halo Globular Cluster Motions (2018, background): “G A ] 1 M ay 2 01 8 MW’s satellite population, particularly the Sagittarius dSph and its impressive tidal stream (Fardal et al. 2018), and the Magellanic Clouds (Kallivayalil et al. 2013).”
Dwarf galaxy planes: the discovery of symmetric structures in the Local Group (2013, background): “Lynden-Bell (1976) discovered that a number of MW satellite galaxies (Draco, LMC, SMC, Ursa Minor), globular clusters (Palomar 1 and 14) and streams align with the orbital plane of the Magellanic Clouds.”
The total mass of the Large Magellanic Cloud from its perturbation on the Orphan stream (2018, background): “For the LMC’s present-day position and velocity, we use proper motions of μ∗α = 1.91 ± 0.02 mas yr−1, μδ = 0.229 ± 0.047 mas yr−1 (Kallivayalil et al. 2013), a radial velocity of vr = 262.2 ± 3.4 km s−1 (van der Marel et al. 2002), and a distance of 49.97 ± 1.126 kpc (Pietrzyński et al. 2013).”
A timing constraint on the (total) mass of the Large Magellanic Cloud (2015, background): “For Andromeda (vlos,vW ,vN) = (−300±4,−119.2±36,−61.9±34)kms−1 (Sohn et al. 2012; D14), LMC (262.2± 3.4,−465± 5,56± 11)kms−1 and SMC (145.6± 0.6,−236± 19,−341± 19)kms−1 (McConnachie 2012; Kallivayalil et al. 2013).”
A-type stars in the Canada–France Imaging Survey – II. Tracing the height of the disc at large distances with Blue Stragglers (2018, methodology): “These were also complemented with two additional runs taking into account the contribution of the Large Magellanic Cloud, assuming a first infall orbit (Besla et al. 2007; Kallivayalil et al. 2013).”
ON THE SHOULDERS OF GIANTS: PROPERTIES OF THE STELLAR HALO AND THE MILKY WAY MASS DISTRIBUTION (2014, background): “…Wang et al. 2012) or its analogue (Robotham et al. 2012), simulating the tidal streams or the orbit of the satellite galaxies (e.g., Newberg et al. 2010), studying the tidal impact of the Galaxy on the satellite galaxies (e.g., Johnston 1998; Kallivayalil et al. 2013; Nichols et al. 2014) etc.”