Odd Galaxy Couple on Space Voyage
The galaxy pair Arp 116. The faint bluish spiral galaxy NGC 4647 is much lower in mass and about two thirds the size of Messier 60, which occupies the center of this image. NGC4647 is roughly the size of our galaxy, the Milky Way. (Credit: NASA/ESA)
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Two very different galaxies drift through space together in this image taken by NASA’s Hubble Space Telescope. The peculiar galaxy pair is called Arp 116.
Arp 116 is composed of a giant elliptical galaxy known as Messier 60, and a much smaller spiral galaxy, NGC 4647.
Messier 60 is the third brightest galaxy in the Virgo cluster of galaxies, a collection of more than 1,300 galaxies. Messier 60 has a diameter of 120,000 light-years, and a mass of about one trillion times that of the sun. A huge black hole of 4.5 billion solar masses lies at its center, one of the most massive black holes ever found.
The faint bluish spiral galaxy NGC 4647 is about two thirds of Messier 60 in size and much lower in mass -- roughly the size of our galaxy, the Milky Way.
Astronomers have long tried to determine whether these two galaxies are actually interacting. Although looking at them from Earth, they overlap, but there is no evidence of new star formation, which would be one of the clearest signs that the two galaxies are indeed interacting. However, recent studies of very detailed Hubble images suggest the onset of some tidal interaction between the two.
This image combines exposures from Hubble’s Advanced Camera for Surveys and Wide Field and Planetary Camera 2.
The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Md., conducts Hubble science operations. STScI is operated by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.
Hubble Watching Ancient Orbs
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This sparkling picture taken by the NASA/ESA Hubble Space Telescope shows the center of globular cluster M 4. The power of Hubble has resolved the cluster into a multitude of glowing orbs, each a colossal nuclear furnace.
M 4 is relatively close to us, lying 7200 light-years distant, making it a prime object for study. It contains several tens of thousands stars and is noteworthy in being home to many white dwarfs — the cores of ancient, dying stars whose outer layers have drifted away into space.
In July 2003, Hubble helped make the astounding discovery of a planet called PSR B1620-26 b, 2.5 times the mass of Jupiter, which is located in this cluster. Its age is estimated to be around 13 billion years — almost three times as old as the Solar System! It is also unusual in that it orbits a binary system of a white dwarf and a pulsar (a type of neutron star).
Amateur stargazers may like to track M 4 down in the night sky. Use binoculars or a small telescope to scan the skies near the orange-red star Antares in Scorpius. M 4 is bright for a globular cluster, but it won’t look anything like Hubble’s detailed image: it will appear as a fuzzy ball of light in your eyepiece
Hubble Spotted a Supernova in NGC 5806
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A new image from the NASA/ESA Hubble Space Telescope shows NGC 5806, a spiral galaxy in the constellation Virgo (the Virgin). It lies around 80 million light years from Earth. Also visible in this image is a supernova explosion called SN 2004dg.
The exposures that are combined into this image were carried out in early 2005 in order to help pinpoint the location of the supernova, which exploded in 2004. The afterglow from this outburst of light, caused by a giant star exploding at the end of its life, can be seen as a faint yellowish dot near the bottom of the galaxy.
NGC 5806 was chosen to be one of a number of galaxies in a study into supernovae because Hubble’s archive already contained high resolution imagery of the galaxy, collected before the star had exploded. Since supernovae are both relatively rare, and impossible to predict with any accuracy, the existence of such before-and-after images is precious for astronomers who study these violent events.
Aside from the supernova, NGC 5806 is a relatively unremarkable galaxy: it is neither particularly large or small, nor especially close or distant.
The galaxy’s bulge (the densest part in the center of the spiral arms) is a so-called disk-type bulge, in which the spiral structure extends right to the center of the galaxy, instead of there being a large elliptical bulge of stars present. It is also home to an active galaxy nucleus, a supermassive black hole which is pulling in large amounts of matter from its immediate surroundings. As the matter spirals around the black hole, it heats up and emits powerful radiation.
This image is produced from three exposures in visible and infrared light, observed by Hubble’s Advanced Camera for Surveys. The field of view is approximately 3.3 by 1.7 arcminutes.
A version of this image was entered into the Hubble’s Hidden Treasures Image Processing Competition by contestant Andre van der Hoeven (who won second prize in the competition for his image of Messier 77). Hidden Treasures is an initiative to invite astronomy enthusiasts to search the Hubble archive for stunning images that have never been seen by the general public. The competition has now closed
