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aethericvisions: Time Lapse of Cepheid Star RS Puppis – Hubble…

aethericvisions:

Time Lapse of Cepheid Star RS Puppis – Hubble Telescope

Allow me to shed some “light “ on what is happening here! (pun intended)

The above phenomenon is known as a Light Echo!

The star seen above – RS Puppis – is a special type of star. RS Puppisis a Cepheid variable star and is one of the brightest known Cepheids in the Milky Way galaxy. A Cepheid variable is a star that pulsates radially, varying in both temperature and diameter to produce brightness changes with a well-defined stable period and amplitude.

A Cepheid Variable Star:

In the Animation of RS Puppis it seems like there are “waves of light“ moving across the image. This is known as a Light Echo. Analogous to an echo of sound, a light echo is produced when a sudden flash or burst of light, such as that observed in the expansion of a Cepheid variable (or a supernova, or some other bright sudden event), is reflected
off a source and arrives at the viewer after a considerably longer
duration than it otherwise would have taken with a direct path. 

A Light Echo:

Light echoes are produced when the initial flash from a rapidly brightening object such as a variable star or supernova is reflected off intervening interstellar dust
which may or may not be associated with the source of the light. Light
from the initial flash arrives at the viewer first, while light
reflected from dust or other objects between the source and the viewer
begins to arrive shortly afterward. Many variations in reflections can be seen below:

The Geometry of a light echo allows astrophysicists to pinpoint the locations of emissions and sources incredibly accurately. Light echoes were used to determine the distance to the Cepheid variable RS Puppis to within 1% of its true value. The team at the European Southern Observatory described this measurement as so far “the most accurate distance to a Cepheid”!

But, Light Echos can also be used to study erupting stars:

In January 2002, a moderately dim star in the constellation Monoceros,
the Unicorn, suddenly became 600 000 times more luminous than our Sun.
This made it temporarily the brightest star in our Milky Way. The light
from this eruption created a unique phenomenon known as a ‘light echo’
when it reflected off dust shells around the star.

Thanks to these light echos, Astronomers were be able to probe the entire 3D structure of the dust
shells surrounding this aging star in much the same way as a doctor does
a CAT scan on a patient.

And for those of you who want a full color version:

Source: Astronomical Wonders

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aethericvisions: Time Lapse of Cepheid Star RS Puppis – Hubble…

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