Skip to main content

A Galaxy on the Edge

Image: This colourful stripe of stars, gas, and dust is actually a spiral galaxy named NGC 1055. Captured here by ESO’s Very Large Telescope (VLT), this big galaxy is thought to be up to 15 percent larger in diameter than the Milky Way. NGC 1055 appears to lack the whirling arms characteristic of a spiral, as it is seen edge-on. However, it displays odd twists in its structure that were probably caused by an interaction with a large neighbouring galaxy. Credit: ESO

Spiral galaxies throughout the Universe take on all manner of orientations with respect to Earth. We see some from above (as it were) or “face-on” — a good example of this being the whirlpool-shaped galaxy NGC 1232.

Image: This spectacular image of the large spiral galaxy NGC 1232 was obtained on September 21, 1998, during a period of good observing conditions. It is based on three exposures in ultra-violet, blue and red light, respectively. The colours of the different regions are well visible : the central areas contain older stars of reddish colour, while the spiral arms are populated by young, blue stars and many star-forming regions. Note the distorted companion galaxy on the left side, shaped like the greek letter "theta". Credit: ESO


Such orientations reveal a galaxy’s flowing arms and bright core in beautiful detail, but make it difficult to get any sense of a three-dimensional shape.

We see other galaxies, such as NGC 3521, at angles.

Image: This picture of the nearby galaxy NGC 3521 was taken using the FORS1 instrument on ESO’s Very Large Telescope, at the Paranal Observatory in Chile. The large spiral galaxy lies in the constellation of Leo (The Lion), and is only 35 million light-years distant. Credit: ESO/O. Maliy


While these tilted objects begin to reveal the three-dimensional structure within their spiral arms, fully understanding the overall shape of a spiral galaxy requires an edge-on view — such as this one of NGC 1055.

When seen edge-on, it is possible to get an overall view of how stars — both new patches of starbirth and older populations — are distributed throughout a galaxy, and the “heights” of the relatively flat disc and the star-loaded core become easier to measure. Material stretches away from the blinding brightness of the galactic plane itself, becoming more clearly observable against the darker background of the cosmos.

Such a perspective also allows astronomers to study the overall shape of a galaxy’s extended disc, and to study its properties. One example of this is warping, which is something we see in NGC 1055. The galaxy has regions of peculiar twisting and disarray in its disc, likely caused by interactions with the nearby galaxy Messier 77. This warping is visible here; NGC 1055’s disc is slightly bent and appears to wave across the core.

NGC 1055 is located approximately 55 million light-years away in the constellation of Cetus (The Sea Monster).


  • Text Credit: ESO
Etichette:

Comments

Post a Comment

Popular posts from this blog

ORBITAL PERIODS OF THE PLANETS

For orbital period generally we refer to the sidereal period, that is the temporal cycle that it takes an object to make a full orbit, relative to the stars. This is the orbital period in an inertial (non-rotating) frame of reference (365,25 days for the earth).
Post a Comment
Read more

Fermi Bubbles

Image: A giant gamma-ray structure was discovered in 2010 by processing Fermi all-sky data at energies from 1 to 10 billion electron volts, shown here. The dumbbell-shaped feature (center) emerges from the galactic center and extends 50 degrees north and south from the plane of the Milky Way, spanning the sky from the constellation Virgo to the constellation Grus. Credits: NASA/DOE/Fermi LAT/D. Finkbeiner et al. At a time when our earliest human ancestors mastered walking upright the heart of our Milky Way galaxy underwent a titanic eruption, driving gases and other material outward at 2 million miles per hour.
Post a Comment
Read more

ABOUT THE FORMATION OF THE COLD CLASSICAL KUIPER BELT

Image: The Kuiper Belt. Credit: NASA . The Kuiper belt is a circumstellar disc in the Solar System beyond the planets, extending from the orbit of Neptune (at 30 AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt (the circumstellar disc located roughly between the orbits of the planets Mars and Jupiter), but it is far larger-20 times as wide and 20 to 200 times as massive.
2 comments
Read more