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: Hubble's new shot of Proxima Centauri, our nearest neighbor

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

How gamma ray telescopes work

19 minutes ago

Yesterday I talked about the detection of gamma ray bursts, intense blasts of gamma rays that occasionally appear in distant galaxies. Gamma ray bursts were only detected when gamma ray satellites were put ...

The frequency of high-energy gamma ray bursts

2 hours ago

In the 1960s a series of satellites were built as part of Project Vela.  Project Vela was intended to detect violations of the 1963 ban on above ground testing of nuclear weapons.  The Vela satellites were ...

What causes the diffraction spikes in images of stars?

2 hours ago

When stars are portrayed in media, they are often shown with long spikes emanating from them. Perhaps the most common example is that of the "star of Bethlehem" which, according to the story, led the wise ...

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.