Turtle in the Stars

Credit: Robert Rubin and Christo­pher Ortiz (NASA Ames Research Cen­ter), Patrick Har­ring­ton and Nancy Jo Lame (Uni­ver­sity of Mary­land), Regi­nald Dufour (Rice Uni­ver­sity), and NASA

The last gasps of Sun-like stars appear in the strangest shapes of glow­ing sea crea­ture, but­ter­flies, insects and turtles.

Explore what appears to be a tur­tle in the stars in this NASA Hub­ble Space Tele­scope image of NGC 6210. Inside the tur­tle, a sun is dying. Bub­bles of mate­r­ial, blown off by the cen­tral star at dif­fer­ent times, give the plan­e­tary neb­ula a lay­ered appear­ance. NGC 6210 was once a star just a lit­tle smaller than our Sun. When a star with a size sim­i­lar to our Sun burns through all of its hydro­gen fuel, the star begins to shed its outer lay­ers and puffs them out into space as giant bub­bles. Radi­a­tion from the now dead stars white, hot core, called a white dwarf, heats the expand­ing shells of gas caus­ing the mate­r­ial to glow. Even­tu­ally, the neb­ula will fade as the mate­r­ial cools and expands into space. The white dwarf will cool and fade slowly from view over the next sev­eral bil­lion years. Our Sun will meet a sim­i­lar fate but not for another five bil­lion years or so.

While astronomers call them plan­e­tary neb­u­lae, they have noth­ing to do with plan­ets. Planet hunters in the 17th and 18th cen­turies cat­a­loged many objects that had an orb-like appear­ance in tele­scopes; much like a planet. Ger­man astronomer Friedrich Georg Wil­hem Struve dis­cov­ered NGC 6210 in 1825. It appears as a bright, but tiny, disk in earth-bound telescopes.

NGC 6210 is located about 6,500 light-years away toward the con­stel­la­tion Her­cules.