TY - JOUR
T1 - The Proper Motion Field of the Small Magellanic Cloud
T2 - Kinematic Evidence for Its Tidal Disruption
AU - Zivick, Paul
AU - Kallivayalil, Nitya
AU - Van Der Marel, Roeland P.
AU - Besla, Gurtina
AU - Linden, Sean T.
AU - Kozłowski, Szymon
AU - Fritz, Tobias K.
AU - Kochanek, C. S.
AU - Anderson, J.
AU - Sohn, Sangmo Tony
AU - Geha, Marla C.
AU - Alcock, Charles R.
N1 - Publisher Copyright:
© 2018. The American Astronomical Society. All rights reserved..
PY - 2018/9/1
Y1 - 2018/9/1
N2 - 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 ∼3 year baseline, using the Hubble Space Telescope (HST) Wide Field Camera 3. Combining this data with our previous five HST fields, and an additional eight measurements from the Gaia-Tycho Astrometric Solution Catalog, brings us to a total of 43 SMC fields. We measure a systemic motion of μ W =-0.82 ± 0.02 (random) ± 0.10 (systematic) mas yr-1 and μ N =-1.21 ± 0.01 (random) ± 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 ± 26 km s-1. We find that in 97% of our considered cases, the Clouds experienced a direct collision 147 ± 33 Myr ago, with a mean impact parameter of 7.5 ± 2.5 kpc.
AB - 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 ∼3 year baseline, using the Hubble Space Telescope (HST) Wide Field Camera 3. Combining this data with our previous five HST fields, and an additional eight measurements from the Gaia-Tycho Astrometric Solution Catalog, brings us to a total of 43 SMC fields. We measure a systemic motion of μ W =-0.82 ± 0.02 (random) ± 0.10 (systematic) mas yr-1 and μ N =-1.21 ± 0.01 (random) ± 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 ± 26 km s-1. We find that in 97% of our considered cases, the Clouds experienced a direct collision 147 ± 33 Myr ago, with a mean impact parameter of 7.5 ± 2.5 kpc.
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U2 - 10.3847/1538-4357/aad4b0
DO - 10.3847/1538-4357/aad4b0
M3 - Article
AN - SCOPUS:85053108023
SN - 0004-637X
VL - 864
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 55
ER -