The revived Near Infrared Camera and Multi-Object Spectrometer (NICMOS) aboard NASA's Hubble Space Telescope has pierced the dusty disk of the "edge-on" galaxy NGC 4013 and peered all the way to the galactic core. To the surprise of astronomers, NICMOS found a brilliant band-like structure, that may be a ring of newly formed stars [yellow band in middle photo] seen edge-on.
In the visible-light view of the galaxy [top photo], the star-forming ring cannot be seen because it is embedded in dust. The most prominent feature in the visible-light image - taken by the Wide Field and Planetary Camera 2 (WFPC2) - is the thin, dark band of gas and dust, which is about 500 light-years thick.
NICMOS enables the Hubble telescope to see in near-infrared wavelengths of light, so that it can penetrate the dust that obscures the inner hub of the galaxy. The ring-like structure spied by NICMOS encircles the core and is about 720 light-years wide, which is the typical size of most star-forming rings found in disk galaxies.
The small ring is churning out stars at a torrid pace. The Milky Way Galaxy, for example, is more than 10,000 times larger than the ring. If the Milky Way produced stars at the same rate, it would be making 1,000 times more stars a year.
The human eye cannot see infrared light, so colors have been assigned to correspond with near-infrared wavelengths. The blue light represents shorter near-infrared wavelengths and the red light corresponds to longer wavelengths.
The ring-like structure is seen more clearly in the photo at bottom. This picture, taken with a filter sensitive to hydrogen, shows the glow of stars and gas. Astronomers used this information to calculate the rate of star formation in the ring-like structure.
The extremely bright star near the center of each picture is a nearby foreground star belonging to our own Milky Way.
Rings of developing stars are common in barred spiral galaxies, which have "bars" of stars and gas slicing across their disks. The bars funnel gas to the galactic cores. But gravitational disturbances near the cores cause gas to accumulate into a lane or a ring. The gas then condenses to form stars. Because NGC 4013 is seen edge-on, astronomers don't know whether a bar of gas or some other mechanism formed the ring-like structure.
NGC 4013, which looks similar to our Milky Way Galaxy, resides in the constellation Ursa Major, 55 million light-years from Earth.
The middle picture is a color composite image that was made by combining photographs taken with the J-band, H-band, and Paschen-alpha filters. The bottom picture was taken with the Paschen-alpha filter. The images were taken on May 12.
Credits
NICMOS images: NASA, the NICMOS Group (STScI, ESA), and the NICMOS Science Team (University of Arizona);WFPC2 image: NASA, The Hubble Heritage Team (STScI/AURA) and ESA
| About The Object | |
|---|---|
| Object Name | NGC 4013 |
| Object Description | Edge-on Spiral Galaxy |
| R.A. Position | 11h 58m 31.39s |
| Dec. Position | 43° 56' 51.0" |
| Constellation | Ursa Major |
| Distance | About 55 million light-years (17 Mpc) |
| Dimensions | This image is about 50 arcseconds (4.1 kiloparsecs or 13,000 light-years) across. |
| About The Data | |
| Data Description | WFPC2 data Principal Astronomers: J. C. Howk (Johns Hopkins University) and B. D. Savage (University of Wisconsin-Madison) NICMOS data Principal Astronomers: D. Calzetti, A. Fruchter, T. Boeker, B. Mobasher, A. Schultz, E. Bergeron, S. Arribas, M. Dickinson, K. Noll, E. Roye, M. Sosey, and C. Xu (STScI) |
| Instrument | HST>WFPC2, and HST>NICMOS/NIC3 |
| Exposure Dates | January 25, 2000 (WFPC2), and May 12, 2002 (NICMOS) |
| Filters | WFPC2 image F814W (I), F555W (V), and F450 (B) NICMOS Infrared image F110W (J-band), F160W (H-band), F187N (Paschen-alpha) NICMOS Hydrogen Light Filter image F187N (Paschen-alpha) |
| About The Image | |
| Color Info | WFPC2 image Blue: F450 (B) Green: F555W (V) Red: F814W (I) NICMOS Hydrogen Light Filter image Red: F187N (Paschen-alpha) |
| 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. |
