NGC 5253

NGC 5253 - HST - Judy Schmidt.png
Autor/Urheber: Judy Schmidt from USA, Lizenz: CC BY 2.0

Here we have wide field view of the compact blue dwarf galaxy NGC 5253, and its epic central starburst. It is something like a smaller, but slightly closer version of M82. Though NGC 5253 is less famous than M82 I still find it to be quite interesting—visually stunning, even. An image I submitted yesterday shows a very high resolution close-up of the core: flic.kr/p/WMcktQ flic.kr/p/WMcktQ

While this galaxy has been previously processed, I thought it would be better if some older narrowband WFPC2 were used to show off its H-alpha emissions, which are now seen clearly here as a bright pink cloud emanating from around the central area of the galaxy. I tried not to overprocess these clouds, but some might say I have. Still, others may say I didn't take it far enough, because it certainly could be pushed even further.

In the upper right and lower left corners are blank areas. I did not want to crop large sections of the galaxy and background off, so I filled these blank areas with a simple noise pattern so that they would not be distracting. H-alpha coverage is incomplete, but close enough that it does not appear to be missing much.

Data from the following two proposals was used. I used mosaics from the LEGUS page, as well as the mosaics from the HLA because some parts of the chip gaps in the LEGUS mosaics did not look very good.

The Discrete X-ray Source Population in NGC~5253, our nearest post-starburst galaxy WFPC2 Mapping of Dust Obscuration and Stellar Populations in Starburst Galaxies.

All channels, in a complicated, but mostly red color: WFPC2 F656N Red: ACS/WFC F814W Green: ACS/WFC F555W Blue: ACS/WFC F435W

North is NOT up. It is 11.7° clockwise from up.

ESP- Big Stellar Cluster in the Blue Dwarf Galaxy NGC 5253-phot-31a-04-fullres.jpg
Autor/Urheber: ESO/NASA/ESA, Lizenz: CC BY 3.0
Composite colour-coded image of the small starburst galaxy NGC 5253, at a distance of 11 million light-years. It is based on one near-infrared image (in the K-band at wavelength 2.16 μm; here coded red) obtained with the ESO Very Large Telescope (VLT) and two images in the visual spectral region (V- (0.55 μm) and I-bands (0.79 μm), here blue and green, respectively) with the NASA/ESA Hubble Space Telescope (HST). The image covers 80 x 80 square arcseconds on the sky. North is up and East is to the left.

A Peculiar Compact Blue Dwarf Galaxy.jpg
Autor/Urheber: ESA/Hubble & NASA Acknowledgement: N. Sulzenauer, Lizenz: CC BY 3.0
The NASA/ESA Hubble Space Telescope provides us this week with an impressive image of the irregular galaxy NGC 5253.

NGC 5253 is one of the nearest of the known Blue Compact Dwarf (BCD) galaxies, and is located at a distance of about 12 million light-years from Earth in the southern constellation of Centaurus. The most characteristic signature of these galaxies is that they harbour very active star-formation regions. This is in spite of their low dust content and comparative lack of elements heavier than hydrogen and helium, which are usually the basic ingredients for star formation.

These galaxies contain molecular clouds that are quite similar to the pristine clouds that formed the first stars in the early Universe, which were devoid of dust and heavier elements. Hence, astronomers consider the BCD galaxies to be an ideal testbed for better understanding the primordial star-forming process.

NGC 5253 does contain some dust and heavier elements, but significantly less than the Milky Way galaxy. Its central regions are dominated by an intense star forming region that is embedded in an elliptical main body, which appears red in Hubble’s image. The central starburst zone consists of a rich environment of hot, young stars concentrated in star clusters, which glow in blue in the image. Traces of the starburst itself can be seen as a faint and diffuse glow produced by the ionised oxygen gas.

The true nature of BCD galaxies has puzzled astronomers for a long time. Numerical simulations following the current leading cosmological theory of galaxy formation, known as the Lambda Cold Dark Matter model, predict that there should be far more satellite dwarf galaxies orbiting big galaxies like the Milky Way. Astronomers refer to this discrepancy as the Dwarf Galaxy Problem.

This galaxy is considered part of the Centaurus A/Messier 83 group of galaxies, which includes the famous radio galaxy Centaurus A and the spiral galaxy Messier 83. Astronomers have pointed out the possibility that the peculiar nature of NGC 5253 could result from a close encounter with Messier 83, its closer neighbour.

This image was taken with the Hubble’s Advanced Camera for Surveys, combining visible and infrared exposures. The field of view in this image is approximately 3.4 by 3.4 arcminutes.

A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Nikolaus Sulzenauer.