HD 161056
A runaway B-type star with variable polarization.
HD 161056 is a bluish-white hued star in the equatorial constellation of Ophiuchus, with an apparent magnitude of 6.32. It is located approximately 1340 light-years distant according to Gaia DR3 parallax measurements and is moving closer at a heliocentric radial velocity of −26.0 km/s. The star is a luminous early B-type object, though its spectral type varies between B1.5V and B3II/III in different publications.
Quick Facts
- Apparent magnitude
- 6.32
- Distance
- approximately 1340 ly
- Radial velocity
- −26.0 km/s
- Spectral type
- B1.5V to B3II/III
- Chinese name
- Shìlóuliù
Facts from the source article.
Did You Know?
- The ESO Diffuse Interstellar Bands Large Exploration Survey detected signatures of diatomic carbon and tricarbon molecules in interstellar clouds surrounding the star.
- Near-infrared spectroscopy has revealed weak stellar emission lines of singly ionized magnesium and neutral helium.
Polarimetry
In 1985, HD 161056 was suggested as a standard for polarimetric observations via the Hubble Space Telescope due to its large distance producing high interstellar polarization and its high luminosity. However, in 1988 it was found to be slightly variable in polarization, making it unsuitable as a standard. Hubble later observed the star's ultraviolet interstellar polarization, with results consistent with Serkowski's law, and the polarization spectrum closely matched expectations for interstellar dust composed of pure amorphous forsterite.
Runaway star
HD 161056 is a runaway star that may produce an infrared bow shock. It likely came from a multiple-star system, possibly ejected by gravitational interactions or a supernova. About 1.1 million years ago, it might have been paired with the pulsar PSR B1929+10 near IC 4665. However, Zeta Ophiuchi is the more probable former companion, with the pair separating roughly 900,000 years ago.
More in Stars of Ophiuchus
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