Starship Asterisk*

bystander wrote: ↑Mon Oct 18, 2021 2:03 pm Hubble Spies a Pair of Squabbling Galaxies
ESA Hubble Picture of the Week | 2021 Oct 18

Credit: ESA/Hubble and NASA, Dark Energy Survey, J. Dalcanton

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This observation from the NASA/ESA Hubble Space Telescope showcases Arp 86, a peculiar pair of interacting galaxies which lies roughly 220 million light-years from Earth in the constellation Pegasus. Arp 86 is composed of the two galaxies NGC 7752 and NGC 7753 — NGC 7753 is the large spiral galaxy dominating this image, and NGC 7752 is its smaller companion. The diminutive companion galaxy almost appears to be attached to NGC 7753, and it is this peculiarity that has earned the designation “Arp 86” — signifying that the galaxy pair appears in the Atlas of Peculiar Galaxies compiled by the astronomer Halton Arp in 1966. The gravitational squabble between the two galaxies is doomed to end catastrophically for NGC 7752. It will eventually either be flung out into intergalactic space or be entirely engulfed by its far larger neighbour.

Hubble observed Arp 86 as part of a larger effort to understand the connections between young stars and the clouds of cold gas in which they form. Hubble gazed into star clusters and clouds of gas and dust in a variety of environments dotted throughout nearby galaxies. Combined with measurements from ALMA, a gigantic radio telescope perched high in the Chilean Andes, these Hubble observations provide a treasure trove of data for astronomers working to understand how stars are born.

These observations also helped sow the seeds of future research with an upcoming space telescope, the NASA/ESA James Webb Space Telescope (JWST). This telescope, due to launch later this year, will study star formation in dusty regions such as the galaxies of Arp 86.

Image Credit: ESO/VLT/MUSE/TIMER Survey

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Captured with the MUSE instrument mounted on ESO’s Very Large Telescope (VLT), this image shows the innermost regions of the distant spiral galaxy NGC 5248, also known as Caldwell 45.

Located around 59 million light-years away from Earth, in the constellation of Boötes, this galaxy is notable for having not one but two rings around its centre. These rings are characterised by “hot spots” of starburst activity. Starburst regions, seen as an orange glow in the picture, are where stars form much more frequently than usual.

MUSE, which stands for Multi Unit Spectroscopic Explorer, is attached to Yepun, one of the four 8.2-metre telescopes that make up the VLT. MUSE decomposes the light of every single pixel within its field of view into its constituent colours or wavelengths. This allows researchers to map complex mechanisms within extended objects, such as analysing the formation of stars in galaxies.

Image Credit: ESA/Hubble & NASA, L. Ho, J. Lee, and the PHANGS-HST Team

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This jewel-bright Picture of the Week features the spiral galaxy NGC 2903. This image was captured using Hubble’s Advanced Camera for Surveys (ACS) and Wide Field Camera 3 (WFC3), which were installed on Hubble in 2002 and 2009 respectively. Interestingly, Hubble has observed this particular galaxy before, in 2001, when neither the ACS or the WFC3 had yet been installed. The 2021 image boasts higher resolution, which means that NGC 2903 is more finely detailed than in the 2001 image. The ACS and WFC2 collectively cover a wide range of ultraviolet, optical and infrared wavelengths, which means that the 2021 image also has superior wavelength coverage to that of its 20-year-old predecessor. The 2001 image was taken using the Wide Field Planetary Camera 2 (WFPC2), which was Hubble’s workhorse instrument from 1993 until 2009 when it was replaced by the WFC3.

Hubble has a long and fascinating history of crewed service missions, which were performed in order to correct for imperfections in Hubble’s mirror, to update Hubble’s technical systems, and to remove old instruments and install new ones. One of Hubble’s most remarkable features is it’s incredible longevity, and this would not have been possible with the great success of the servicing missions. The juxtaposition of the 2001 and 2021 images of NGC 2903 — both remarkable images for their time — highlights the value of a stable, accessible platform in space that can reliably collect data, not only year after year, but decade after decade.