A dying star, IC 4406, dubbed the "Retina Nebula" is revealed in this month's Hubble Heritage image.
Like many other so-called planetary nebulae, IC 4406 exhibits a high degree of symmetry; the left and right halves of the Hubble image are nearly mirror images of the other. If we could fly around IC 4406 in a starship, we would see that the gas and dust form a vast donut of material streaming outward from the dying star. From Earth, we are viewing the donut from the side. This side view allows us to see the intricate tendrils of dust that have been compared to the eye's retina. In other planetary nebulae, like the Ring Nebula (NGC 6720), we view the donut from the top.
The donut of material confines the intense radiation coming from the remnant of the dying star. Gas on the inside of the donut is ionized by light from the central star and glows. Light from oxygen atoms is rendered blue in this image; hydrogen is shown as green, and nitrogen as red. The range of color in the final image shows the differences in concentration of these three gases in the nebula.
Unseen in the Hubble image is a larger zone of neutral gas that is not emitting visible light, but which can be seen by radio telescopes.
One of the most interesting features of IC 4406 is the irregular lattice of dark lanes that criss-cross the center of the nebula. These lanes are about 160 astronomical units wide (1 astronomical unit is the distance between the Earth and Sun). They are located right at the boundary between the hot glowing gas that produces the visual light imaged here and the neutral gas seen with radio telescopes. We see the lanes in silhouette because they have a density of dust and gas that is a thousand times higher than the rest of the nebula. The dust lanes are like a rather open mesh veil that has been wrapped around the bright donut.
The fate of these dense knots of material is unknown. Will they survive the nebula's expansion and become dark denizens of the space between the stars or simply dissipate?
This image is a composite of data taken by Hubble's Wide Field Planetary Camera 2 in June 2001 by Bob O'Dell (Vanderbilt University) and collaborators and in January 2002 by The Hubble Heritage Team (STScI). Filters used to create this color image show oxygen, hydrogen, and nitrogen gas glowing in this object.
Credits
NASA and The Hubble Heritage Team (STScI/AURA);Acknowledgment: C.R. O'Dell (Vanderbilt University)
| About The Object | |
|---|---|
| Object Name | IC 4406, Retina Nebula |
| Object Description | Bipolar Planetary Nebula |
| R.A. Position | 14h 22m 25.79s |
| Dec. Position | -44° 9' 0.0" |
| Constellation | Lupus |
| Distance | About 600 parsecs (1900 light-years) |
| Dimensions | The diameter across the short dimension of the nebula is 0.08 parsecs (0.25 light-years) while the long dimension is 3.6 times as large. |
| About The Data | |
| Data Description | Principal Astronomers: C.R. O'Dell (Vanderbilt University) , B. Balick (U. Washington), A. Burkert (Max Planck Institute for Astronomy-Heidelberg), A. Hajian (USNO), W. Henney (UNAM, Morelia) Hubble Heritage Team: K. Noll, H. Bond, C. Christian, L. Frattare, F. Hamilton, J. Lee, Z. Levay, P. Royle (STScI) |
| Instrument | HST>WFPC2 |
| Exposure Dates | June 28, 2001; January 19, 2002, Exposure Time: 1.3 hours |
| Filters | F502N ([O III]), F656N (H-alpha), F658N ([N II]) |
| About The Image | |
| 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. |
