NASA's Hubble Space Telescope captured two festive-looking nebulas, situated so as to appear as one. They reside in the Small Magellanic Cloud, a dwarf galaxy that is a satellite of our Milky Way galaxy. Intense radiation from the brilliant central stars is heating hydrogen in each of the nebulas, causing them to glow red.
The nebulas, together, are called NGC 248. They were discovered in 1834 by the astronomer Sir John Herschel. NGC 248 is about 60 light-years long and 20 light-years wide. It is among a number of glowing hydrogen nebulas in the dwarf satellite galaxy, which is located approximately 200,000 light-years away in the southern constellation Tucana.
The image is part of a study called Small Magellanic Cloud Investigation of Dust and Gas Evolution (SMIDGE). Astronomers are using Hubble to probe the Milky Way satellite to understand how dust is different in galaxies that have a far lower supply of heavy elements needed to create dust. The Small Magellanic Cloud has between a fifth and a tenth of the amount of heavy elements that the Milky Way does. Because it is so close, astronomers can study its dust in great detail, and learn about what dust was like earlier in the history of the universe. "It is important for understanding the history of our own galaxy, too," explained the study's principal investigator, Dr. Karin Sandstrom of the University of California, San Diego. Most of the star formation happened earlier in the universe, at a time where there was a much lower percentage of heavy elements than there is now. "Dust is a really critical part of how a galaxy works, how it forms stars," said Sandstrom.
The data used in this image were taken with Hubble's Advanced Camera for Surveys in September 2015.
Credits
NASA, ESA, STScI, K. Sandstrom (University of California, San Diego), and the SMIDGE team| About The Object | |
|---|---|
| Object Name | NGC 248, DEM S 16, SMC N13 |
| Object Description | Star-forming Nebula |
| R.A. Position | 00h 45m 24.07s |
| Dec. Position | -73° 22' 44.40" |
| Constellation | Tucana |
| Distance | 197,000 light-years (61 kiloparsecs) |
| About The Data | |
| Data Description | These datasets are from the HST proposal , P.I.: K. Sandstrom (University of California, San Diego). |
| Instrument | HST>ACS/WFC |
| Exposure Dates | September 2015 |
| Filters | F475W (B), F550M (narrow V), F658N (H-alpha), and F814W (i) |
| About The Image | |
| Color Info | This image is combined from separate exposures acquired by HST's ACS/WFC instrument. Four filters were used to sample different wavelength bands. The color results from assigning different hues (colors) to each monochromatic (grayscale) image associated with an individual filter. In this case, the assigned colors are: Blue: F475W (B) Green: F550M (narrow V) Orange: F658N (H-alpha) Red: F814W (i) |
| Compass Image |  |
| About The Object | |
|---|---|
| Object Name | A name or catalog number that astronomers use to identify an astronomical object. |
| Object Description | The type of astronomical object. |
| R.A. Position | Right ascension – analogous to longitude – is one component of an object's position. |
| Dec. Position | Declination – analogous to latitude – is one component of an object's position. |
| Constellation | One of 88 recognized regions of the celestial sphere in which the object appears. |
| Distance | The physical distance from Earth to the astronomical object. Distances within our solar system are usually measured in Astronomical Units (AU). Distances between stars are usually measured in light-years. Interstellar distances can also be measured in parsecs. |
| Dimensions | The physical size of the object or the apparent angle it subtends on the sky. |
| About The Data | |
| Data Description |
|
| Instrument | The science instrument used to produce the data. |
| Exposure Dates | The date(s) that the telescope made its observations and the total exposure time. |
| Filters | The camera filters that were used in the science observations. |
| About The Image | |
| Image Credit | The primary individuals and institutions responsible for the content. |
| Publication Date | The date and time the release content became public. |
| Color Info | A brief description of the methods used to convert telescope data into the color image being presented. |
| Orientation | The rotation of the image on the sky with respect to the north pole of the celestial sphere. |
