Today's Amateur Astronomy Photo of the Day:

Zeta Ophiuchi & the Bow Shock

Zeta Ophiuchi is the third brightest star in the constellation Ofiucus; with magnitude +2.54, it is a main sequence blue star located 440 light years from Earth, with a mass 20 times greater than that of the Sun.

Like the stars of its class, it emits matter through large amounts of stellar winds, at a speed of 1600 km/s. Part of this interstellar material is ionized by star radiation, resulting in the Sh2-27 emission nebula.

Zeta Ophiuchi is a star from a complex past, likely expelled from her birthplace by a powerful star explosion.

Previous observations have shown that Zeta Ophiuchi was once in a close orbit with another star, before being ejected at about 160,000 kilometers per hour when this companion was destroyed by a supernova explosion over a million years ago.

The Zeta Ophiuchi leak produces this kind of shock wave called bow shock due to its strong stellar wind that precedes it, compressing and heating the dusty interstellar material and modeling the compression wave.