NASA's Hubble Space Telescope captured a detailed image of NGC 6951, a famous galaxy in the constellation Cepheus. This galaxy is known for its star formation history, unique classification, and multiple supernova events, providing astronomers with valuable insights into the workings of the universe.
The Hubble Space Telescope captured this complex image of NGC 6951, the Cepheus galaxy. Image credit: NASA Hubble Space Telescope, ESA, A. Filippenko (University of California, Berkeley), R. Foley (University of California, Santa Cruz), C. Kilpatrick (Northwestern University), and D. Sand (University of Arizona); Processing: Gladys Koher (NASA/The Catholic University of America)
Bright blue spiral arms swirl around the luminous white center of this starry galaxy. This new NASA Hubble Space Telescope image shows NGC 6951, an intermediate spiral galaxy 78 million light-years away in the constellation Cepheus.
NGC 6951 was discovered independently by French astronomer Jerome Coggia in 1877 and American astronomer Lewis Swift in 1878. Its stellar history has aroused the interest of scientists. The galaxy's star formation rate peaked about 800 million years ago, then sat quietly for 300 million years before starting to form stars again. The average age of star clusters, or groups of gravitationally bound stars in this galaxy, is 200 to 300 million years old, although some clusters are as old as a billion years. Turbulent regions of gas (shown in dark red) surround bright blue pinholes (star clusters).
Astronomers generally classify NGC 6951 as a Type II Seyfert galaxy, an active galaxy that emits large amounts of infrared radiation and has slow-moving gaseous material near its center. Some astronomers classify NGC 6951 as a Low Ionization Nuclear Emission Line Region (LINER) galaxy, which is similar to a Type II Seyfert galaxy but has a cooler core that emits weakly ionized or neutral atoms such as oxygen, nitrogen, and sulfur. The entire galaxy is about 75,000 light-years in diameter and can be seen from the northern hemisphere due to its proximity to the North Celestial Pole.
NGC 6951 has a supermassive black hole at its center, surrounded by a ring of stars, gas and dust about 3,700 light-years across. This "ring" is between 1 and 1.5 billion years old and has been forming stars for much of that time. Scientists speculate that interstellar gas flows through the Milky Way's dense star-shaped bars to the perinuclear ring, providing new material for star formation. Up to 40% of the mass in the ring comes from relatively young stars less than 100 million years old. Spiral dust lanes, shown in dark orange, connect the Milky Way's center to its outer regions, providing more material for future star formation.
Some stars in NGC 6951 have also experienced horrific stellar explosions called supernovae; astronomers count as many as six supernovae in this galaxy in the past 25 years. Scientists continue to study NGC 6951 to better understand the environment that produces supernovae. Studying supernova emission helps astronomers understand the progenitor star, its age, luminosity and location. The image uses data from the Hubble Wide Field Camera 3 (WFC3) and the Advanced Camera for Surveys (ACS). Data were performed under visible and infrared light.