RS Puppis puts on a spectacular light show

Dec 17, 2013
This Hubble image shows RS Puppis, a type of variable star known as a Cepheid variable. As variable stars go, Cepheids have comparatively long periods — RS Puppis, for example, varies in brightness by almost a factor of five every 40 or so days. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)-Hubble/Europe Collaboration Acknowledgment: H. Bond (STScI and Penn State University)

The NASA/ESA Hubble Space Telescope has observed the variable star RS Puppis over a period of five weeks, showing the star growing brighter and dimmer as it pulsates. These pulsations have created a stunning example of a phenomenon known as a light echo, where light appears to reverberate through the murky environment around the star.

For most of its life, a star is pretty stable, slowly consuming the fuel at its core to keep it shining brightly.

However, once most of the hydrogen that stars use as fuel has been consumed, some stars evolve into very different beasts—pulsating stars. They become unstable, expanding and shrinking over a number of days or weeks and growing brighter and dimmer as they do so.

A new and spectacular Hubble image shows RS Puppis, a type of known as a Cepheid variable. As variable go, Cepheids have comparatively long periods. RS Puppis, for example, varies in brightness by almost a factor of five every 40 or so days.

RS Puppis is unusual as it is shrouded by a nebula—thick, dark clouds of gas and dust. Hubble observed this star and its murky environment over a period of five weeks in 2010, capturing snapshots at different stages in its cycle and enabling scientists to create a time-lapse video of this ethereal object.

The apparent motion shown in these Hubble observations is an example of a phenomenon known as a light echo. The dusty environment around RS Puppis enables this effect to be shown with stunning clarity. As the star expands and brightens, we see some of the light after it is reflected from progressively more distant shells of dust and gas surrounding the star, creating the illusion of gas moving outwards. This reflected light has further to travel, and so arrives at the Earth after light that travels straight from star to telescope. This is analogous to sound bouncing off surrounding objects, causing the listener to hear an audible echo. In 2008, astronomers used the around RS Puppis to measure its distance from us, obtaining the most accurate measurement of a Cepheid's distance.

While this effect is certainly striking in itself, there is another important scientific reason to observe Cepheids like RS Puppis. The period of their pulsations is known to be directly connected to their intrinsic brightness, a property that allows astronomers to use them as cosmic distance markers. This helps us to measure and understand the vast scale of the Universe.

Explore further: What's the brightest star in the sky, past and future?

Related Stories

Star explosion leaves behind a rose

Dec 12, 2011

(PhysOrg.com) -- About 3,700 years ago, people on Earth would have seen a brand-new bright star in the sky. It slowly dimmed out of sight and was eventually forgotten, until modern astronomers later found ...

Light echoes from V838 Mon

Mar 19, 2013

(Phys.org) —What caused this outburst of V838 Mon? For reasons unknown, star V838 Mon's outer surface suddenly greatly expanded with the result that it became the brightest star in the entire Milky Way ...

NASA Hubble sees sparring antennae galaxies

Nov 18, 2013

The NASA/ESA Hubble Space Telescope has snapped the best ever image of the Antennae Galaxies. Hubble has released images of these stunning galaxies twice before, once using observations from its Wide Field ...

The Cosmic Distance Scale

Jan 29, 2010

(PhysOrg.com) -- In 1908, Harvard astronomer Henrietta Swan Leavitt discovered that a class of stars called Cepheids have brightnesses that vary regularly with periods that are directly related to their intrinsic ...

Recommended for you

Could the Milky Way become a quasar?

Feb 27, 2015

A quasar is what you get when a supermassive black hole is actively feeding on material at the core of a galaxy. The region around the black hole gets really hot and blasts out radiation that we can see billions ...

Galactic dinosaurs not extinct

Feb 27, 2015

One of the biggest mysteries in galaxy evolution is the fate of the compact massive galaxies that roamed the early Universe.

Stars found forming at Milky Way's outer edge

Feb 27, 2015

Brazilian astronomers said Friday they had found two star clusters forming in a remote part of our Milky Way galaxy where such a thing was previously thought impossible.

New insight found in black hole collisions

Feb 26, 2015

New research by an astrophysicist at The University of Texas at Dallas provides revelations about the most energetic event in the universe—the merging of two spinning, orbiting black holes into a much larger ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

cantdrive85
1 / 5 (6) Dec 17, 2013
Is it a light echo? Or more likely glow mode plasma? There are three modes of plasma, arc, glow and dark mode. The image shows all three, the star is arc mode, the filamentary clouds are glow mode, and the interstellar space is dark mode.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.