University of Surrey

Test tubes in the lab Research in the ATI Dance Research

The total mass of the Large Magellanic Cloud from its perturbation on the Orphan stream

Erkal, D, Belokurov, V, Laporte, C F P, Koposov, S E, Li, T S, Grillmair, C J, Kallivayalil, N, Price-Whelan, A M, Evans, N W, Hawkins, K , Hendel, D, Mateu, C, Navarro, J F, Pino, A del, Slater, C T and Sohn, S T (2019) The total mass of the Large Magellanic Cloud from its perturbation on the Orphan stream Monthly Notices of the Royal Astronomical Society.

The total mass of the Large Magellanic Cloud from its perturbation on the Orphan stream - AAM.pdf - Accepted version Manuscript

Download (2MB) | Preview


In a companion paper by Koposov et al., RR Lyrae from Gaia Data Release 2 are used to demonstrate that stars in the Orphan stream have velocity vectors significantly misaligned with the stream track, suggesting that it has received a large gravitational perturbation from a satellite of the Milky Way. We argue that such a mismatch cannot arise due to any realistic static Milky Way potential and then explore the perturbative effects of the Large Magellanic Cloud (LMC). We find that the LMC can produce precisely the observed motion-track mismatch and we therefore use the Orphan stream to measure the mass of the Cloud. We simultaneously fit the Milky Way and LMC potentials and infer that a total LMC mass of 1.38+0.27−0.24×1011M is required to bend the Orphan Stream, showing for the first time that the LMC has a large and measurable effect on structures orbiting the Milky Way. This has far-reaching consequences for any technique which assumes that tracers are orbiting a static Milky Way. Furthermore, we measure the Milky Way mass within 50 kpc to be 3.80+0.14−0.11×1011M⁠. Finally, we use these results to predict that, due to the reflex motion of the Milky Way in response to the LMC, the outskirts of the Milky Way’s stellar halo should exhibit a bulk, upwards motion.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Physics
Authors :
Belokurov, V
Laporte, C F P
Koposov, S E
Li, T S
Grillmair, C J
Kallivayalil, N
Price-Whelan, A M
Evans, N W
Hawkins, K
Hendel, D
Mateu, C
Navarro, J F
Pino, A del
Slater, C T
Sohn, S T
Date : 2019
Funders : European Union’s Seventh Framework Programme
DOI : 10.1093/mnras/stz1371
Copyright Disclaimer : © 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (
Uncontrolled Keywords : Galaxy: kinematics and dynamics. Galaxy: halo. Galaxy: structure. Galaxy: evolution. Galaxies: Magellanic Clouds.
Depositing User : Clive Harris
Date Deposited : 23 May 2019 13:52
Last Modified : 23 May 2019 13:53

Actions (login required)

View Item View Item


Downloads per month over past year

Information about this web site

© The University of Surrey, Guildford, Surrey, GU2 7XH, United Kingdom.
+44 (0)1483 300800