St Andrews Research Repository

St Andrews University Home
View Item 
  •   St Andrews Research Repository
  • University of St Andrews Research
  • University of St Andrews Research
  • University of St Andrews Research
  • View Item
  •   St Andrews Research Repository
  • University of St Andrews Research
  • University of St Andrews Research
  • University of St Andrews Research
  • View Item
  •   St Andrews Research Repository
  • University of St Andrews Research
  • University of St Andrews Research
  • University of St Andrews Research
  • View Item
  • Login
JavaScript is disabled for your browser. Some features of this site may not work without it.

Testing Gravity with Wide Binary stars like α Centauri

Thumbnail
View/Open
Wide_binary_Proxima.pdf (1.597Mb)
Date
21/10/2018
Author
Banik, Indranil
Zhao, Hongsheng
Keywords
Gravitation
Dark matter
Proper motions
Binaries: general
Galaxy: disc
Stars: individual: Proxima Centauri
QB Astronomy
QC Physics
Astronomy and Astrophysics
DAS
Metadata
Show full item record
Altmetrics Handle Statistics
Altmetrics DOI Statistics
Abstract
We consider the feasibility of testing Newtonian gravity at low accelerations using wide binary (WB) stars separated by >∼ 3 kAU. These systems probe the accelerations at which galaxy rotation curves unexpectedly flatline, possibly due to Modified Newtonian Dynamics (MOND). We conduct Newtonian and MOND simulations of WBs covering a grid of model parameters in the system mass, semi-major axis, eccentricity and orbital plane. We self-consistently include the external field (EF) from the rest of the Galaxy on the Solar neighbourhood using an axisymmetric algorithm. For a given projected separation, WB relative velocities reach larger values in MOND. The excess is ≈20% adopting its simple interpolating function, as works best with a range of Galactic and extragalactic observations. This causes noticeable MOND effects in accurate observations of ≈500 WBs, even without radial velocity measurements. We show that the proposed Theia mission may be able to directly measure the orbital acceleration of Proxima Cen towards the 13 kAU-distant α Cen. This requires an astrometric accuracy of ≈1 μas over 5 years. We also consider the long-term orbital stability of WBs with different orbital planes. As each system rotates around the Galaxy, it experiences a time-varying EF because this is directed towards the Galactic Centre. We demonstrate approximate conservation of the angular momentum component along this direction, a consequence of the WB orbit adiabatically adjusting to the much slower Galactic orbit. WBs with very little angular momentum in this direction are less stable over Gyr periods. This novel direction-dependent effect might allow for further tests of MOND.
Citation
Banik , I & Zhao , H 2018 , ' Testing Gravity with Wide Binary stars like α Centauri ' , Monthly Notices of the Royal Astronomical Society , vol. 480 , no. 2 , pp. 2660–2688 . https://doi.org/10.1093/mnras/sty2007
Publication
Monthly Notices of the Royal Astronomical Society
Status
Peer reviewed
DOI
https://doi.org/10.1093/mnras/sty2007
ISSN
0035-8711
Type
Journal article
Rights
© 2018, the Author(s). This work has been made available online in accordance with the publisher’s policies. This is the author created accepted version manuscript following peer review and as such may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1093/mnras/sty2007
Description
Funding: IB was partially supported by Science and Technology Facilities Council studentship 1506672.
Collections
  • University of St Andrews Research
URL
https://academic.oup.com/mnras/article/480/2/2660/5060764?guestAccessKey=180aba7d-6e2a-4ec5-89c6-21a9556bfda3
https://arxiv.org/abs/1805.12273
URI
http://hdl.handle.net/10023/15735

Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.

Advanced Search

Browse

All of RepositoryCommunities & CollectionsBy Issue DateNamesTitlesSubjectsClassificationTypeFunderThis CollectionBy Issue DateNamesTitlesSubjectsClassificationTypeFunder

My Account

Login

Open Access

To find out how you can benefit from open access to research, see our library web pages and Open Access blog. For open access help contact: openaccess@st-andrews.ac.uk.

Accessibility

Read our Accessibility statement.

How to submit research papers

The full text of research papers can be submitted to the repository via Pure, the University's research information system. For help see our guide: How to deposit in Pure.

Electronic thesis deposit

Help with deposit.

Repository help

For repository help contact: Digital-Repository@st-andrews.ac.uk.

Give Feedback

Cookie policy

This site may use cookies. Please see Terms and Conditions.

Usage statistics

COUNTER-compliant statistics on downloads from the repository are available from the IRUS-UK Service. Contact us for information.

© University of St Andrews Library

University of St Andrews is a charity registered in Scotland, No SC013532.

  • Facebook
  • Twitter