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Spiral galaxy seen in a new light

Infrared view of NGC 1365

An infrared view of NGC 1365, a beautiful barred spiral galaxy in the Fornax cluster of galaxies, about 60 million light-years from Earth.

  • Galaxy NGC 1365, the Great Barred Spiral Galaxy
  • 200,000 light-years wide, with two huge spiral arms
  • Located 60 million light-years from Earth

A new image taken with the powerful HAWK-I camera on the European Southern Observatory’s (ESO’s) Very Large Telescope in Chile shows the beautiful “barred spiral” galaxy NGC 1365 in infrared light.

NGC 1365 is a member of the Fornax cluster of galaxies, about 60 million light-years from Earth.

NGC 1365 is one of the best-known and most-studied barred spiral galaxies, sometimes nicknamed the Great Barred Spiral Galaxy because of its strikingly perfect form…a straight “bar” or middle section and two prominent outer spiral arms.

Closer to the centre there is also a second spiral structure, and the galaxy as a whole is laced with delicate lanes of interstellar dust.

Astronomers consider it an excellent “laboratory” for studying how spiral galaxies form and evolve.

The new infrared images from HAWK-I are less affected by the dust that obscures parts of the galaxy than images taken at visible light wavelengths, and they reveal very clearly the glow from vast numbers of stars in both the bar and the spiral arms.

The images were acquired to help astronomers understand the complex flow of gas within the galaxy and how it affects the reservoirs of gas from which new stars can form.

The huge bar disturbs the shape of the gravitational field of the galaxy and this leads to regions where gas becomes compressed, triggering the formation of new stars.

See the full-size, high-resolution version of the image (suitable for PC wallpaper) here.

Visible light and infrared views of NGC 1365

This comparison shows a visible-light image (left) of NGC 1365 along with the new infrared view (right). The infrared view "peels away" the veil of dust to reveal more stars beneath.

Black hole hidden in the core

Many huge young star clusters are visible in the main spiral arms, each containing hundreds or thousands of bright young stars that are less than 10 million years old.

The galaxy is too remote for single stars to be seen—most of the tiny clumps visible in the picture are really clusters of stars.

While the bar of the galaxy comprises mainly older stars long past their prime, many new stars are born in stellar “nurseries” of gas and dust in the inner spiral close to the core. Over the whole galaxy, stars are forming at a rate of about three times the mass of our Sun per year.

The bar also funnels gas and dust gravitationally into the very centre of the galaxy, where astronomers have found evidence for the presence of a super-massive black hole, well hidden among myriads of intensely bright new stars.

Here’s a video that zooms in on NGC 1365, alternating between visible wavelength and infrared wavelength views:

NGC 1365, including its two huge outer spiral arms, is around 200,000 light-years across. Different parts of the galaxy take different times to make a full rotation around the core, with the outer parts of the bar taking about 350 million years to complete one circuit.

NGC 1365 and other galaxies of its type have come to more prominence in recent years with new observations indicating that our Milky Way galaxy could also be of the barred spiral type.

Such galaxies are quite common—two thirds of spiral galaxies are barred according to recent estimates. Studying them can help astronomers understand our own galactic home.

Adapted from information issued by ESO / P. Grosbøl.

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Dive into the Lagoon Nebula

Close-up shot of the centre of the Lagoon Nebula

This close-up shot of the centre of the Lagoon Nebula clearly shows the delicate structures formed when the powerful radiation of young stars interacts with the hydrogen cloud from which they formed.

  • Lagoon Nebula, a famous “starbirth” region
  • Located 4,000 to 5,000 light-years away
  • Evidence that stars and planets are forming within

The Advanced Camera for Surveys (ACS) on Hubble Space Telescope has captured a dramatic view of gas and dust sculpted by intense radiation from hot young stars deep in the heart of the Lagoon Nebula (also known as Messier 8).

This spectacular object is named after the wide, lagoon-shaped dust lane that crosses the glowing gas of the nebula.

This dust lane structure is prominent in wide-field images, but cannot be seen in this close-up. However the strange billowing shapes and sandy texture visible in this image make the Lagoon Nebula’s watery name eerily appropriate from this viewpoint too.

Here’s a video pan across the new Hubble image:

Located 4,000 to 5,000 light-years away, Messier 8 is a huge region of star birth that stretches across 100 light-years. Clouds of hydrogen gas are slowly collapsing to form new stars, whose bright ultraviolet rays then light up the surrounding gas in a distinctive shade of red.

See the full-size, high-resolution version of the image here.

Wide-field image of the Lagoon Nebula

A wide-field image shows the entirety of the Lagoon Nebula. The Hubble image focuses on a tiny portion in the heart of the Nebula, just below and to the right of centre.

The wispy tendrils and beach-like features of the nebula are not caused by the ebb and flow of tides, but rather by ultraviolet radiation’s ability to erode and disperse the gas and dust into the distinctive shapes that we see.

In recent years astronomers probing the secrets of the Lagoon Nebula have found the first unambiguous evidence that star formation by accumulation of matter from the gas cloud is ongoing in this region.

Young stars that are still surrounded by a swirling cloud of gas and dust occasionally shoot out long tendrils of matter from their poles. Several examples of these jets, known as Herbig-Haro objects, have been found in this nebula in the last five years, providing strong support for astronomers’ theories about star formation in such hydrogen-rich regions.

Watch this impressive zoom-in video, which takes us from the outer reaches of the Milky Way and into the Lagoon:

The Lagoon Nebula is faintly visible to the naked eye on dark nights as a small patch of grey in the heart of the Milky Way. Without a telescope, the nebula looks underwhelming because human eyes are unable to distinguish clearly between colours at low light levels.

Charles Messier, the 18th century French astronomer, studied the nebula and included it in his famous astronomical catalogue, from which the nebula’s alternative name comes. But his relatively small refracting telescope would only have hinted at the dramatic structures and colours now visible thanks to Hubble.

Adapted from information issued by Spacetelescope.org / NASA / A. Caulet (ST-ECF, ESA) / Hunter Wilson.

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