This NASA/ESA Hubble Space Telescope image shows a spiral galaxy known as NGC 7331. First spotted by the prolific galaxy hunter William Herschel in 1784, NGC 7331 is located about 45 million light-years away in the constellation of Pegasus (The Winged Horse). Facing us partially edge-on, the galaxy showcases it’s beautiful arms which swirl like a whirlpool around its bright central region.

Astronomers took this image using Hubble’s Wide Field Camera 3 (WFC3), as they were observing an extraordinary exploding star — a supernova — which can still be faintly seen as a tiny red dot near the galaxy’s central yellow core. Named SN2014C, it rapidly evolved from a supernova containing very little Hydrogen to one that is Hydrogen-rich — in just one year. This rarely observed metamorphosis was luminous at high energies and provides unique insight into the poorly understood final phases of massive stars.

NGC 7331 is similar in size, shape, and mass to the Milky Way. It also has a comparable star formation rate, hosts a similar number of stars, has a central supermassive black hole and comparable spiral arms. The primary difference between our galaxies is that NGC 7331 is an unbarred spiral galaxy — it lacks a “bar” of stars, gas and dust cutting through its nucleus, as we see in the Milky Way. Its central bulge also displays a quirky and unusual rotation pattern, spinning in the opposite direction to the galactic disc itself.

By studying similar galaxies we hold a scientific mirror up to our own, allowing us to build a better understanding of our galactic environment which we cannot always observe, and of galactic behaviour and evolution as a whole.

Credit:
NASA/ESA and The Hubble Heritage Team (STScI/AURA)

These images, taken a year apart by the NASA/ESA Hubble Space Telescope, reveal a shadow moving counterclockwise around a gas and dust disc encircling the young star TW Hydrae.

The two images at the top, taken by the Space Telescope Imaging Spectrograph, show an uneven brightness across the disc. Through enhanced image processing (images at bottom), the darkening becomes even more apparent. These enhanced images allowed astronomers to determine the reason for the changes in brightness.

The dimmer areas of the disc (top left) are caused by a shadow spreading across the outer disc. The dotted lines approximate the shadow's coverage. The long arrows show how far the shadow has moved in a year (from 2015-2016), which is roughly 20 degrees.

Based on Hubble archival data, astronomers determined that the shadow completes a rotation around the central star every 16 years. They know the feature is a shadow because dust and gas in the disc do not orbit the star nearly that quickly. So, the feature must not be part of the physical disc.

The shadow may be caused by the gravitational effect of an unseen planet orbiting close to the star. The planet pulls up material from the main disc, creating a warped inner disc. The twisted disc blocks light from the star and casts a shadow onto the disc's outer region.

Links:

• NASA Press release
• The making of a shadow in TW Hydrae's disc (illustration)

Credit:
NASA/ESA and The Hubble Heritage Team (STScI/AURA)

A bright and bizarre galaxy called NGC 2623 is the focus of this Hubblecast. The single galaxy is the product of the merger of two distinct galaxies. The union has spawned new star formation and activated one of the supermassive black holes found at the centres of the two original galaxies, causing it to emit light across a wide spectrum. The galaxy is part of the GOALS (The Great Observatory All-sky LIRG) Survey that combines the powers of four space telescopes to study over 200 of the most luminous infrared galaxies in the local Universe.

ESA/Hubble
Visual design & Editing: Martin Kornmesser
Animations: Martin Kornmesser & Patrik Jonsson, Greg Novak & Joel Primack, UC Santa Cruz
Web Technical Support: Lars Holm Nielsen & Raquel Yumi Shida
Written by: Colleen Sharkey
Narration: Dr. J
Music: movetwo & John Dyson from the CD Darklight
Still images: XMM-Newton: ESA/Chandra: NASA/Galex: NASA/JPL-Caltech/ Spitzer: NASA/JPL-Caltech
Directed by: Colleen Sharkey
Executive director: Lars Lindberg Christensen
Acknowledgement: Dr. Eckhard Sturm

Credit:
NASA/ESA and The Hubble Heritage Team (STScI/AURA)

This image, taken with the Advanced Camera for Surveys aboard the NASA/ESA Hubble Space Telescope, shows the newly discovered planet, Fomalhaut b, orbiting its parent star, Fomalhaut.

The small white box at lower right pinpoints the planet's location. Fomalhaut b has carved a path along the inner edge of a vast, dusty debris ring encircling Fomalhaut that is 34.5 billion kilometres across. Fomalhaut b lies three billion kilometres inside the ring's inner edge and orbits 17 billion kilometres from its star.

The inset at bottom right is a composite image showing the planet's position during Hubble observations taken in 2004 and 2006. Astronomers have calculated that Fomalhaut b completes an orbit around its parent star every 872 years.


The white dot in the centre of the image marks the star's location. The region around Fomalhaut's location is black because astronomers used the Advanced Camera's coronagraph to block out the star's bright glare so that the dim planet could be seen. Fomalhaut b is 100 million times fainter than its star. The radial streaks are scattered starlight. The red dot at lower left is a background star.

The Fomalhaut system is 25 light-years away in the constellation Piscis Austrinus.

This false-colour image was taken in October 2004 and July 2006.

Credit:
NASA, ESA and P. Kalas (University of California, Berkeley, USA)