Stellar rotation

PSR B1509−58 is a pulsar approximately at a distance of 17,000 light-years in the constellation of Circinus discovered by the Einstein X-Ray Observatory in 1982. Its diameter is only 12 miles (19 km). It is located in a Pulsar wind nebula created by itself, that was caused as a remnant of the Supernova (SNR) MSH 15−52 visual approximately 1,700 years ago at the southern celestial hemisphere not visible in the Northern Hemisphere. The nebula spans about 150 light years. The 0.1515 second pulsations ("6.597 times per second") are detected in the radio, X-ray, and γ-ray bands.

NASA described the star as "a rapidly spinning neutron star which is spewing energy out into the space around it to create complex and intriguing structures, including one that resembles a large cosmic hand". It is also known by the name "Hand of God". This phenomenon is called pareidolia.

A solar radius is a unit of distance, commonly understood as 695,700 km and expressed as ${\displaystyle R_{\odot }}$, used mostly to express the size of an astronomical objects relative to that of the Sun, or their distance from it. This length is also called the nominal solar radius. The sun's actual radius, from which the unit of measurement is derived, is usually calculated as the radius from the sun's center out to the layer in the Sun's photosphere where the optical depth equals 2/3. One solar radius can be described as follows:$${\displaystyle 1\,R_{\odot }=6.957\times 10^{8}{\hbox{ m}}}$$This is an approximation: both because such distance is difficult to measure and can be measured in various ways, and because the sun is not a perfectly spherical object itself, and thus the actual radius varies depending on the point(s) measured and modality of measurement employed.

695,700 kilometres (432,300 miles) is approximately 10 times the average radius of Jupiter; 109 times the 6378 km radius of the Earth at its equator; and ${\textstyle {1 \over 215}}$ or 0.0047 of an astronomical unit, the approximate average distance between Earth and the Sun. The solar radius to the sun's poles and that to the equator differ slightly due to the Sun's rotation, which induces an oblateness in the order of 10 parts per million.

BO Microscopii (BO Mic) is a star in the constellation Microscopium located about 170 light-years (52 parsecs; 11 million astronomical units) from the Sun. It has been dubbed "Speedy Mic" because of its very rapid rotation. The projected rotational velocity at the equator of this star is about 135 km/s (84 mi/s), which, with an estimated inclination of 70° to the line of sight from the Earth, means it completes a rotation every 0.380 ± 0.004 days (9.120 ± 0.096 hours).

The photosphere of this star shows a high level of magnetic activity, with multiple star spots and prominences observed at the same time. As many as 25 prominences have been observed simultaneously, extending outward as far as 3.6 times the radius of the star. BO Mic is a flare star that undergoes sudden increases in X-ray and ultraviolet emissions. These events can emit a hundred times more energy than large solar flares. Speedy Mic is one of the most active stars in the vicinity of the Sun.

Achernar is the brightest star in the constellation of Eridanus and the ninth-brightest in the night sky. It has the Bayer designation Alpha Eridani, which is Latinized from α Eridani and abbreviated Alpha Eri or α Eri. The name Achernar applies to the primary component of a binary system. The two components are designated Alpha Eridani A (the primary) and B (the secondary), with the latter known informally as Achernar B. As determined by the Hipparcos astrometry satellite, this system is located at a distance of approximately 139 light-years (43 parsecs) from the Sun.

Of the ten brightest stars in the night-time sky by apparent magnitude, Alpha Eridani is the hottest and bluest in color because it is spectral type B. Achernar has an unusually rapid rotational velocity, causing it to become oblate in shape. The secondary is smaller, is spectral type A, and orbits Achernar at a distance of 7.35 AU.