Deviation of stellar orbits from test particle trajectories around SGr A* due to tides and winds

Dimitrios Psaltis, Gongjie Li, Abraham Loeb

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Monitoring the orbits of stars around Sgr A* offers the possibility of detecting the precession of their orbital planes due to frame dragging, of measuring the spin and quadrupole moment of the black hole, and of testing the no-hair theorem. Here we investigate whether the deviations of stellar orbits from test-particle trajectories due to wind mass loss and tidal dissipation of the orbital energy compromise such measurements. We find that the effects of stellar winds are, in general, negligible. On the other hand, for the most eccentric orbits (e > 0.96) for which an optical interferometer, such as GRAVITY, will detect orbital plane precession due to frame dragging, the tidal dissipation of orbital energy occurs at timescales comparable to the timescale of precession due to the quadrupole moment of the black hole. As a result, this non-conservative effect is a potential source of systematic uncertainty in testing the no-hair theorem with stellar orbits.

Original languageEnglish (US)
Article number57
JournalAstrophysical Journal
Issue number1
StatePublished - Nov 1 2013


  • Galaxy: center
  • black hole physics

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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