NGC 7331

NGC7331 - HST - Potw1805a.tif
(c) ESA/Hubble, CC BY 4.0
Twins with differences

This NASA/ESA Hubble Space Telescope image shows a spiral galaxy known as NGC 7331. First spotted by the prolific galaxy hunter William Herschel in 1784, NGC 7331 is located about 45 million light-years away in the constellation of Pegasus (The Winged Horse). Facing us partially edge-on, the galaxy showcases it’s beautiful arms which swirl like a whirlpool around its bright central region.

Astronomers took this image using Hubble’s Wide Field Camera 3 (WFC3), as they were observing an extraordinary exploding star — a supernova — which can still be faintly seen as a tiny red dot near the galaxy’s central yellow core. Named SN2014C, it rapidly evolved from a supernova containing very little Hydrogen to one that is Hydrogen-rich — in just one year. This rarely observed metamorphosis was luminous at high energies and provides unique insight into the poorly understood final phases of massive stars.

NGC 7331 is similar in size, shape, and mass to the Milky Way. It also has a comparable star formation rate, hosts a similar number of stars, has a central supermassive black hole and comparable spiral arms. The primary difference between our galaxies is that NGC 7331 is an unbarred spiral galaxy — it lacks a “bar” of stars, gas and dust cutting through its nucleus, as we see in the Milky Way. Its central bulge also displays a quirky and unusual rotation pattern, spinning in the opposite direction to the galactic disc itself.

By studying similar galaxies we hold a scientific mirror up to our own, allowing us to build a better understanding of our galactic environment which we cannot always observe, and of galactic behaviour and evolution as a whole.

Credit:

ESA/Hubble & NASA/D. Milisavljevic (Purdue University)

Coordinates
Position (RA):	22 37 5.34
Position (Dec):	34° 24' 31.42"
Field of view:	2.68 x 2.01 arcminutes
Orientation:	North is 56.3° right of vertical

Colours & filters Band	Wavelength	Telescope
Optical u	336 nm	Hubble Space Telescope WFC3
Ultraviolet uv	275 nm	Hubble Space Telescope WFC3
Optical B	438 nm	Hubble Space Telescope WFC3
Optical V	555 nm	Hubble Space Telescope WFC3
Optical I	814 nm	Hubble Space Telescope WFC3
Optical H-Alpha +NIII	657 nm	Hubble Space Telescope WFC3

.

N7331s.jpg
Autor/Urheber: Credit Line and Copyright Adam Block/Mount Lemmon SkyCenter/University of Arizona, Lizenz: CC BY-SA 3.0 us
NGC 7331

Picture Details:

   Optics            24-inch RC Optical Systems Telescope
   Camera            SBIG STL11000 CCD Camera
   Filters           Custom Scientific
   Dates             September 10th-13th 2009
   Location          Mount Lemmon SkyCenter
   Exposure          LRGB = 180:100:90:100 minutes
   Acquisition       ACP Observatory Control Software (DC-3 Dreams),TheSky (Software Bisque), Maxim DL/CCD (Cyanogen)
   Processing        CCDStack (CCDWare), Mira (MiraMetrics), Maxim DL (Cyanogen), Photoshop CS3 (Adobe)
   Guest Astronomers:                   September 2009 Image Processing Workshop Participants

Credit Line and Copyright Adam Block/Mount Lemmon SkyCenter/University of Arizona

NGC 7331 GALEX WIKISKY.png
UV-Image of NGC 7331 made by GALEX

Caldwell Catalogue.jpg
Autor/Urheber: Roberto Mura, Lizenz: CC BY-SA 3.0
Caldwell Catalogue objects.

NGC 7331 Ssc2004-12a1.png
Spitzer Composite View of NGC 7331

This composite infrared image from NASA's Spitzer Space Telescope has captured a nearby spiral galaxy that resembles our own Milky Way. The galaxy, known as NGC 7331 and sometimes referred to as our galaxy's twin, is found in the constellation Pegasus at a distance of 50 million light-years. This inclined galaxy was discovered in 1784 by William Herschel, who also discovered infrared light.

The evolution of this galaxy is a story that depends significantly on the amount and distribution of gas and dust, the locations and rates of star formation, and on how the energy from star formation is recycled by the local environment. The new Spitzer images are allowing astronomers to "read" this story by dissecting the galaxy into its separate components.

The image, measuring 12.6 by 8.2 arcminutes, was obtained by Spitzer's infrared array camera. It is a four-color composite of invisible light, showing emissions from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (yellow) and 8.0 microns (red). These wavelengths are roughly 10 times longer than those seen by the human eye.

The infrared light seen in this image originates from two very different sources. At shorter wavelengths (3.6 to 4.5 microns - shown as blue), the light comes mainly from stars, particularly ones that are older and cooler than our Sun. This starlight fades at longer wavelengths (5.8 to 8.0 microns - shown as red), where instead we see the glow from clouds of interstellar dust. This dust consists mainly of a variety of carbon-based organic molecules known collectively as polycyclic aromatic hydrocarbons. Wherever these compounds are found, there will also be dust granules and gas, which provide a reservoir of raw materials for future star formation.

Perhaps the most intriguing feature seen at longer-wavelength is a ring of dust girdling the galaxy center. This ring, with a radius of nearly 20,000 light-years, is invisible at shorter wavelengths, yet has been detected at sub-millimeter and radio wavelengths. It is made up in large part of polycyclic aromatic hydrocarbons. Spitzer measurements suggest that the ring contains enough gas to produce four billion stars like the Sun. Starlight was systematically subtracted from the longer-wavelength picture to enhance dust features.

Three other galaxies are seen below NGC 7331, all about 10 times farther away. From left to right are NGC 7336, NGC 7335 and NGC 7337. The blue dots scattered throughout the image are foreground stars in the Milky Way; the red ones are galaxies that are even more distant.

The Spitzer observations of NGC 7311 are part of a large 500-hour science project, known as the Spitzer Infrared Nearby Galaxy Survey, which will comprehensively study 75 nearby galaxies with infrared imaging and spectroscopy.