Red giant star Betelgeuse is shrinking

Orion’s red supergiant Betelgeuse has been steadily shrinking over the last 15 years.

Betelgeuse is so big that if placed in our Solar System it would extend to the orbit of Jupiter. But thanks to long term monitoring by Berkeley’s Infrared Spatial Interferometer (ISI) at Mt Wilson, measurements of the star’s diameter reveal the giant to be shrinking. Over the last 15 years, the star has shrunk by more than 15 percent, equivalent to the same diameter as the orbit of Venus.

Despite its diminished size however, there is no evidence to suggest that the star is dimming. But we do not know why the star is shrinking.

Since the star’s size depends on the wavelength of light used to measure it, it is difficult to compare measurements. Tenuous gas in the outer regions of the star emits light as well as absorbs it, which presents a challenge in determining the edge of the star.

Spitzer telescope detects dust around carbon star

Dust plays an important role in the evolution of galaxies like our Milky Way.

With the help of NASA's Spitzer space telescope researchers have observed dust forming around the carbon star MAG 29, located 280,000 light years away from a smaller galaxy called the Sculptor Dwarf . Stars more massive than the sun end their lives as carbon stars, which in our galaxy are a rich source of dust.

The Sculptor Dwarf contains only 4% of the carbon and other heavy elements in our own galaxy.

The more we can understand the quantity and composition of the dust , the more we can understand how stars and galaxies evolve.