This composite radio light image and rendition of our galaxy as seen in visible light shows enigmatic "high-velocity clouds" of gas high above the plane of the Milky Way which rain gas into the galaxy, seeding it with the stuff of stars.
The cloud outlined, and possibly others too, is now known to have low heavy element content and to be raining down onto the Milky Way disk, seeding it with material for star birth. Identifying this infalling gas helps in solving a long-standing mystery of galactic evolution by revealing a source of the low-metallicity gas required to explain the observed chemical composition of stars near the Sun.
In this all-sky projection, the edge-on plane of our galaxy appears as a white horizontal strip. The false-color orange-yellow "clouds" are regions containing neutral hydrogen, which glows in 21-centimeter radiation. Hubble Space Telescope's spectrograph was aimed at one of the clouds (encircled) to measure its detailed composition and velocity.
This discovery is based on a combination of data from NASA's Hubble Space Telescope, three radio telescopes (at Effelsberg in Germany, and Dwingeloo and Westerbork in the Netherlands), the William Herschel Telescope on the island of La Palma and the Wisconsin H-alpha Mapper at NOAO's Kitt Peak Observatory.
Credits
Image composite by Ingrid Kallick of Possible Designs, Madison Wisconsin. The background Milky Way image is a drawing made at Lund Observatory. High-velocity clouds are from the survey done at Dwingeloo Observatory (Hulsbosch & Wakker, 1988).| About The Object | |
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| Object Name | Milky Way |
| About The Object | |
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| 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 |
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| 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. |
