Akari's observations of galaxy M101

September 7, 2007
Akari's observations of galaxy M101
This is a composite image of the spiral galaxy M101. The image shows the distribution of cold (blue) and warm (red) dust overlaid on the visible (green, showing distribution of stars) and far-ultraviolet (cyan, indicating the location of young stars) images of M101. Credits: Composite: JAXA, visible (green): the National Geographic Society, far-ultraviolet (cyan): GALEX/NASA

M101 is a spiral galaxy, 170 000 light-years in diameter. AKARI’s new observations reveal differing populations of stars spread across its spiral arms.

Toyoaki Suzuki at the University of Tokyo conducted observations of M101 with AKARI at four infrared wavelengths (65, 90, 140, and 160 micrometres) using the Far-Infrared Surveyor (FIS) instrument.

Many young high-temperature stars populate the spiral arms, revealing the areas of star formation and warming the interstellar dust. This causes the galaxy to shine at shorter infrared wavelengths. In contrast, the longer wavelengths show where the ‘cold’ dust is located. Normal stars, typically like our own Sun, warm this dust.

FIS data was compared to an image of M101 in the visible and far-ultraviolet. It shows that warm dust is distributed along the spiral arms, with many hot spots located along the outer edge of the galaxy. These spots correspond to giant star-forming regions. This is unusual because star formation is generally more active in the central parts of spiral galaxies.

The evidence points to M101 having experienced a close encounter with a companion galaxy in the past, dragging out gas from the hapless companion. The gas is now falling onto the outer edge of M101 at approximately 150 km/s, triggering the active star formation.

Source: ESA

Explore further: Astronomers discover low surface brightness galaxies with amateur telescopes

Related Stories

Astronomers find seven dwarf galaxies with new telescope

July 10, 2014

Meet the seven new dwarf galaxies. Yale University astronomers, using a new type of telescope made by stitching together telephoto lenses, recently discovered seven celestial surprises while probing a nearby spiral galaxy. ...

Pinwheeling across the sky

June 11, 2013

(Phys.org) —The face-on Pinwheel spiral galaxy is seen at ultraviolet wavelengths in this image taken by ESA's XMM-Newton space telescope.

Professional and amateur astronomers join forces

April 24, 2014

(Phys.org) —Long before the term "citizen science" was coined, the field of astronomy has benefited from countless men and women who study the sky in their spare time. These amateur astronomers devote hours exploring the ...

Supernova 'brightens up' September 7-8

September 8, 2011

(PhysOrg.com) -- The nearest supernova of its type to be discovered for 40 years is predicted to be at its brightest 7-8 September and will be visible through a good pair of binoculars.

Recommended for you

The hottest white dwarf in the Galaxy

November 25, 2015

Astronomers at the Universities of Tübingen and Potsdam have identified the hottest white dwarf ever discovered in our Galaxy. With a temperature of 250,000 degrees Celsius, this dying star at the outskirts of the Milky ...

Hubble captures a galactic waltz

November 26, 2015

This curious galaxy—only known by the seemingly random jumble of letters and numbers 2MASX J16270254+4328340—has been captured by the NASA/ESA Hubble Space Telescope dancing the crazed dance of a galactic merger. The ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.