Andromeda
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Star

S5-HVS1

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A star flung out of the Milky Way at about 1,700 km/s by the black hole at its centre, Sagittarius A*.

Measured

Distance
about 28,980 light-years (published estimates 28,640–29,030)
Constellation
Grus
Position (J2000)
RA 22h 54m 51s, Dec −51.20°

How far, from the Sun

About 29,000 light-years. To cross it:

  • Light29,000 years
  • Voyager 1's speed515 million years
  • Driving at 100 km/h313 billion years

Voyager 1 at the speed it moved outward over the year to 2026-10-25 (JPL Horizons). Driving: nonstop, never refuelling.

Facts

  • Tracing its path back leads to the Galactic Centre about 4.8 million years ago, when it left at about 1,800 km/s (Koposov et al. 2020) — the line drawn from Sagittarius A*.
  • It is crossing the Galaxy at about 1,755 km/s, fast enough to leave the Milky Way for ever.
  • The likeliest story: it was one of a pair, and the black hole kept its partner (the Hills mechanism — the paper weighs others).
  • It is a white A-type star of about 2.35 Suns.

Where this comes from

  • Koposov et al. 2020, MNRAS 491, 2465 (8,884 ± 11 pc if it left the Galactic Centre; about 8.6 ± 0.3 kpc from its light alone)
  • This research has made use of the SIMBAD database, CDS, Strasbourg, France (Wenger et al. 2000, A&AS 143, 9).
  • This research has made use of the VizieR catalogue access tool, CDS, Strasbourg, France (DOI: 10.26093/cds/vizier).

Every catalogue Ouranos draws is credited on the credits page.