The SDSS has definitely seen hundreds of HII regions in nearby galaxies. But using the SDSS to study HII regions presents an issue. Because the SDSS sees so plenty of objects in the sky, the survey makes use of a computer program called Picture to classify the objects as stars, galaxies, cosmic rays, ghosts (false optical images), or moving objects. Overall, Picture does an excellent job of identifying the objects SDSS sees.
Most spiral galaxies contain star-forming regions rich in ionized hydrogen. Ionized hydrogen is also called HII, so the star forming regions are known as "HII (pronounced 'H-two') regions." Because stars are actively forming inside HII regions, astronomers are interested in studying the regions.
But, nearby spiral galaxies that appear giant in our field of view cause issues for Picture. When Picture examines a galaxy like the below, in lieu of classifying it as galaxy, Picture breaks it up in to several parts! Picture often mistakes the core and the HII regions in a galaxy for separate galaxies. Sometimes Picture can look at a single galaxy and mistakenly see up to four separate galaxies.The next version of Picture ought to fix the issue of HII region misidentification. But until astronomers know how lots of regions have been misidentified by the current version of Picture, they will never know whether the next version is actually an improvement. & although astronomers agree that a catalog of misidentified HII regions is important to checking the accuracy of the survey, none of them has made such a catalog. You can help.
To tell the difference between a single galaxy with misidentified HII regions & genuine multiple galaxies, a program called Plate selects objects for the SDSS will measure spectra. The SDSS cannot measure spectra for all the objects it sees, so Plate selects which objects to examine. Sometimes Plate selects HII regions for spectral analysis. By taking a look at both images & spectra for the same galaxy, you can tell which places are HII regions misidentified by Picture, & which are actually separate galaxies.
Your mission, ought to you select to accept it, is to find the HII regions for which the SDSS has acquired spectra. This information will let you study HII regions in detail, learn how well our Picture program works, & give us a comparison for when they start using a brand spanking new, & hopefully improved, version of Picture.
The only way to be definite you have identified an HII region is to visually inspect the SDSS field that contains the galaxy. Information Release six (the information you see on SkyServer) contains spectra of over 350,000 galaxies, so you cannot visually inspect every. Additionally, some of the galaxies are very small, & it can be hard to tell what you are seeing, so you require other proof to tell whether you are taking a look at an HII region or a whole galaxy. This method may appear tedious, but it is an important part of astronomy: SDSS astronomers have visually inspected hundreds of galaxies for papers they have written.
Most spiral galaxies contain star-forming regions rich in ionized hydrogen. Ionized hydrogen is also called HII, so the star forming regions are known as "HII (pronounced 'H-two') regions." Because stars are actively forming inside HII regions, astronomers are interested in studying the regions.
But, nearby spiral galaxies that appear giant in our field of view cause issues for Picture. When Picture examines a galaxy like the below, in lieu of classifying it as galaxy, Picture breaks it up in to several parts! Picture often mistakes the core and the HII regions in a galaxy for separate galaxies. Sometimes Picture can look at a single galaxy and mistakenly see up to four separate galaxies.The next version of Picture ought to fix the issue of HII region misidentification. But until astronomers know how lots of regions have been misidentified by the current version of Picture, they will never know whether the next version is actually an improvement. & although astronomers agree that a catalog of misidentified HII regions is important to checking the accuracy of the survey, none of them has made such a catalog. You can help.
To tell the difference between a single galaxy with misidentified HII regions & genuine multiple galaxies, a program called Plate selects objects for the SDSS will measure spectra. The SDSS cannot measure spectra for all the objects it sees, so Plate selects which objects to examine. Sometimes Plate selects HII regions for spectral analysis. By taking a look at both images & spectra for the same galaxy, you can tell which places are HII regions misidentified by Picture, & which are actually separate galaxies.
Your mission, ought to you select to accept it, is to find the HII regions for which the SDSS has acquired spectra. This information will let you study HII regions in detail, learn how well our Picture program works, & give us a comparison for when they start using a brand spanking new, & hopefully improved, version of Picture.
The only way to be definite you have identified an HII region is to visually inspect the SDSS field that contains the galaxy. Information Release six (the information you see on SkyServer) contains spectra of over 350,000 galaxies, so you cannot visually inspect every. Additionally, some of the galaxies are very small, & it can be hard to tell what you are seeing, so you require other proof to tell whether you are taking a look at an HII region or a whole galaxy. This method may appear tedious, but it is an important part of astronomy: SDSS astronomers have visually inspected hundreds of galaxies for papers they have written.