NASA's Hubble Finds Surprises Around a Star That Erupted 40 Years Ago

Credit: Artwork: NASA, ESA, Leah Hustak (STScI)

This artist’s concept shows the nova system HM Sagittae (HM Sge), where a white dwarf star is pulling material from its red giant companion. This forms a blazing hot disk around the dwarf, which can unpredictably undergo a spontaneous thermonuclear explosion as the infall of hydrogen from the red giant grows denser and reaches a tipping point. These fireworks between companion stars are fascinating to astronomers by yielding insights into the physics and dynamics of stellar evolution in binary systems.

« NASA's Hubble Finds Surprises Around a Star That Erupted 40 Years Ago

Credit: Science: NASA, ESA, Ravi Sankrit (STScI), Steven Goldman (STScI)

A Hubble Space Telescope image of the symbiotic star Mira HM Sge. Located 3,400 light-years away in the constellation Sagitta, it consists of a red giant and a white dwarf companion. The stars are too close together to be resolved by Hubble. Material bleeds off the red giant and falls onto the dwarf, making it extremely bright. This system first flared up as a nova in 1975. The red nebulosity is evidence of the stellar wind. The nebula is about one-quarter light-year across.

« NASA's Hubble Finds Surprises Around a Star That Erupted 40 Years Ago

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