The Hydrogen Clouds of M33 : Gorgeous spiral galaxy M33 seems to have more than its fair share of glowing hydrogen gas. A prominent member of the local group of galaxies, M33 is also known as the Triangulum Galaxy and lies about 3 million light-years distant. The galaxy’s inner 30,000 light-years or so are shown in this telescopic portrait that enhances its reddish ionized hydrogen clouds or HII regions. Sprawling along loose spiral arms that wind toward the core, M33’s giant HII regions are some of the largest known stellar nurseries, sites of the formation of short-lived but very massive stars. Intense ultraviolet radiation from the luminous, massive stars ionizes the surrounding hydrogen gas and ultimately produces the characteristic red glow. To enhance this image, broadband data was used to produce a color view of the galaxy and combined with narrowband data recorded through a hydrogen-alpha filter. That filter transmits the light of the strongest visible hydrogen emission line. via NASA
Familiar stars in Orion and constellations across the sky now have official names. Over the past year, the International Astronomical Union, the only body officially tasked with naming stars, approved names already in common use for 227 of the brightest stars, including the most famous stars on the sky Sirius, Polaris, and Betelgeuse. Pictured, the constellation of Orion is shown with several of these now-official star names superposed. Spanning about 30 degrees, this breath-taking vista stretches across the well-known constellation from head to toe (left to right) and beyond. The common names for all three stars in Orion’s belt are also now official. At 1,500 light years away, the Great Orion Nebula is the closest large star forming region, here visible just right and below center. Also visible are famous nebulae including the Horsehead Nebula and the Witch Head Nebula. Of course, the Orion Nebula and bright stars are easy to see with the unaided eye, but dust clouds and emission from the extensive interstellar gas in this nebula-rich complex, are too faint and much harder to record. In the featured mosaic of broadband telescopic images, additional image data acquired with a narrow hydrogen alpha filter was used to bring out the pervasive tendrils of energized atomic hydrogen gas like in the arc of the giant Barnard’s Loop.
Trifid Nebula - M20, NGC 6514
The Trifid Nebula, M20, is a must-have object for any astrophotographer in the Constellation of Sagittarius. It has a beautiful red/magenta emission nebula, captured here with the red and Hydrogen-alpha filters, partially covered by dense tendrils of dust. The region is an intense stellar nursery for new star creation. The emission nebula smoothly transitions into a bluish reflection nebula toward the north (lower left), where gas and dust reflect light from intense, nearby blue stars. There is also a considerable amount of dust trailing off into the background.
This image shows off the impressive imaging capabilities of the new CCD detectors in the Mosaic 1.1 camera on the Mayall 4-meter telescope at Kitt Peak National Observatory. The image is of Sharpless 2-188 (Sh2-188), an unusual planetary nebula located in the constellation Cassiopeia. The expanding gas from the planetary nebula is colliding with ambient gas in the interstellar medium. The nebula is nearly circular in shape but is much brighter to the southeast (lower left) because the central star is moving rapidly in that direction. Faint wisps of gas can also be seen in the opposite direction. The image was generated with deep observations in the Hydrogen alpha filter (red) and the Oxygen [OIII] filter (cyan). In this image, North is up and East is to the left.
Image Credit: T.A. Rector/University of Alaska Anchorage, H. Schweiker/WIYN AND NOAO/AURA/NSF
nasa-official!!!!!! why is it that the Rosette nebula only appears red in some photos? Is that how it appears optically, or is that just how it appears in one of the spectra that we read it in?
Well whenever you see red in nebulae, thats typically due to hydrogen being excited. The Rosette Nebula is actually classified as an H II region. H II (singly ionized hydrogen) regions are caused by some source of energy, kicking the electron out of the hydrogen atom and keeping it out.
So Rosette is definitely red. To strengthen this effect, pictures are often taken using a Hydrogen-Alpha filter which (you guessed it) only lets the light in from this transition!!! But, sometimes people want to look at what’s going on in the nebula in different wavelengths too