Hubble sees the graceful dance of 2 interacting galaxies

Oct 30, 2007
Hubble sees the graceful dance of 2 interacting galaxies
Arp 87 is a stunning pair of interacting galaxies. Stars, gas and dust flow from the large spiral galaxy, NGC 3808, forming an enveloping arm around its companion. The shapes of both galaxies have been distorted by their gravitational interaction. Arp 87 is located in the constellation of Leo, the Lion, approximately 300 million light-years away from Earth. Arp 87 appears in Arp's Atlas of Peculiar Galaxies. As also seen in similar interacting galaxies, the corkscrew shape of the tidal material suggests that some stars and gas drawn from the larger galaxy have been caught in the gravitational pull of the smaller one. This image was taken in February 2007 with Hubble's Wide Field Planetary Camera 2 detector. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

A pair of galaxies, known collectively as Arp 87, is one of hundreds of interacting and merging galaxies known in our nearby Universe. Arp 87 was originally discovered and catalogued by astronomer Halton Arp in the 1970s. Arp’s Atlas of Peculiar Galaxies is a compilation of astronomical photographs using the Palomar 200-inch Hale and the 48-inch Samuel Oschin telescopes.

The resolution in the Hubble image shows exquisite detail and fine structure that was not observable when Arp 87 was first discovered in the 1970’s.

The two main players comprising Arp 87 are NGC 3808 on the right (the larger of the two galaxies) and its companion NGC 3808A on the left. NGC 3808 is a nearly face-on spiral galaxy with a bright ring of star formation and several prominent dust arms. Stars, gas, and dust flow from NGC 3808, forming an enveloping arm around its companion. NGC 3808A is a spiral galaxy seen edge-on and is surrounded by a rotating ring that contains stars and interstellar gas clouds. The ring is situated perpendicular to the plane of the host galaxy disk and is called a “polar ring.”

As seen in other mergers similar to Arp 87, the corkscrew shape of the tidal material or bridge of shared matter between the two galaxies suggests that some stars and gas drawn from the larger galaxy have been caught in the gravitational pull of the smaller one.

The shapes of both galaxies have been distorted by their gravitational interaction with one another.

Interacting galaxies often exhibit high rates of star formation. Many lines of evidence – colours of their starlight, intensity of emission lines from interstellar gas, far-infrared output from heated interstellar dust – support this fact. Some merging galaxies have the highest levels of star formation we can find anywhere in the nearby Universe.

A major aspect of this excess star formation could be properly revealed only when Hubble turned its imaging capabilities toward colliding galaxies. Among the observatory’s first discoveries was that galaxies with very active star formation contain large numbers of super star clusters – clusters more compact and richer in young stars than astronomers were accustomed to seeing in our galactic neighbourhood.

Arp 87 is in the constellation Leo, the Lion, approximately 300 million light-years away from Earth. These observations were taken in February 2007 with the Wide Field Planetary Camera 2. Light from isolated blue, green, red, and infrared ranges was combined to form this colour image.

Source: ESA/Hubble Information Centre

Explore further: Comet Jacques makes a 'questionable' appearance

add to favorites email to friend print save as pdf

Related Stories

Hubble spots galaxies in close encounter

Jun 20, 2013

(Phys.org) —The NASA/ESA Hubble Space Telescope has produced this vivid image of a pair of interacting galaxies known as Arp 142. When two galaxies stray too close to each other they begin to interact, ...

A family portrait of galaxies

Sep 06, 2012

(Phys.org)—Two very different galaxies feature in this family portrait taken by the NASA/ESA Hubble Space Telescope, together forming a peculiar galaxy pair called Arp 116. The image shows the dramatic ...

Galaxy harbors many star-snacking black holes

Jul 02, 2012

(Phys.org) -- Astronomers have found evidence of hundreds of black holes in a galaxy 250 million light years away. The discovery, made with a worldwide network of radio telescopes, gives scientists a new way ...

Multiple mergers generate ultraluminous infrared galaxy

Jun 22, 2012

A team of astronomers led by Professor Yoshiaki Taniguchi (Ehime University) has concluded that the ultraluminous infrared galaxy (ULIRG) Arp 220 developed from a multiple merger among four or more galaxies. ...

The star factory: observing Arp 220

Feb 18, 2012

Using the Herschel Space Observatory, Wilson's group has found Arp 220 to have large amounts of very warm molecular hydrogen gas, a surprising find that implies molecular hydrogen is the dominant coolant in the high-temperature ...

Recommended for you

Comet Jacques makes a 'questionable' appearance

8 hours ago

What an awesome photo! Italian amateur astronomer Rolando Ligustri nailed it earlier today using a remote telescope in New Mexico and wide-field 4-inch (106 mm) refractor. Currently the brightest comet in ...

Image: Our flocculent neighbour, the spiral galaxy M33

8 hours ago

The spiral galaxy M33, also known as the Triangulum Galaxy, is one of our closest cosmic neighbours, just three million light-years away. Home to some forty billion stars, it is the third largest in the ...

Image: Chandra's view of the Tycho Supernova remnant

Jul 25, 2014

More than four centuries after Danish astronomer Tycho Brahe first observed the supernova that bears his name, the supernova remnant it created is now a bright source of X-rays. The supersonic expansion of ...

User comments : 3

Adjust slider to filter visible comments by rank

Display comments: newest first

earls
2 / 5 (1) Oct 30, 2007
I assume that the region between the galaxies that are interacting are incapable of supporting life... But could you imagine if they were? That'd be a helluva ride. :)
fredrick
not rated yet Oct 30, 2007
I don't see why it would be incapable of supporting life, presuming there is a decent sized star or two being pulled between the two galaxies which can provide heat for a rocky planet orbitting it a certain distance away.


How much of a ride would it be? Our planet orbits our sun fairly fast but we don't exactly feel it; and neither do we feel the fact that our solar system orbits the center of our galaxy at however many hundreds of miles a second. Besides that, the trip wouldn't exactly be a short one - two or three hundred thousand years at the speed of light maybe? not exactly a roller coaster ride.
earls
1 / 5 (1) Oct 30, 2007
the speed of light, squared.
fredrick
Oct 30, 2007
This comment has been removed by a moderator.