In a holiday image courtesy of the Hubble Space Telescope, the Cepheid variable star RS Puppis, 10 times more massive than the sun and 200 times larger, shines in a wreath-like “gossamer cocoon” of dust, brightening and dimming over a 41.5-day cycle. RS Puppis has an average intrinsic brightness 15,000 times greater than the Sun’s and is one of the most luminous Cepheids in the Milky Way. As it pulsates, the surrounding nebula flashes in wave like “light echoes. By measuring those fluctuations and the faint light echoes moving across the nebula, astronomers have been able to establish the distance to RS Puppis with high precision. The European Southern Observatory’s New Technology Telescope found that distance to be about 6,500 light years in 2008. Follow-on studies by Hubble in 2014 came up with a slightly lower value. The European Space Agency’s Gaia spacecraft was able to directly measure the distance to RS Puppis using geometric parallax, coming up with a value of 5,580 (plus or minus 260) light years.
This NASA/ESA Hubble Space Telescope image reveals a delicate blue group of stars — actually an irregular galaxy named IC 3583 — that sits some 30 million light-years away in the constellation of Virgo. This small galaxy is thought to be gravitationally interacting with one of its neighbours, the spiral Messier 90.
With a temperature of 250,000 °C — 45 times that at the surface of our Sun — astronomers believe that this dying star in the outskirts of the Milky Way may have peaked at 400,000 °C a thousand years ago. The researchers were also the first to observe an intergalactic gas cloud moving towards the Milky Way — indicating that galaxies collect fresh material from deep space, which they can use to make new stars.
The fuzzy collection of stars seen in this NASA/ESA Hubble Space Telescope image forms an intriguing dwarf galaxy named LEDA 677373, located about 14 million light-years away from us in the constellation Centaurus. This particular dwarf galaxy contains a plentiful reservoir of gas from which it could form stars, but it stubbornly refuses to do so. Why?