Background Information: Supplemental Science Information for NGC 2174 (Monkey Head Nebula)
The prime source of energy in the nebula is the massive, hot star HD 42088, outside the Hubble image field, but the brightest single star above center left in the wider field of the ground-based image. This star has a mass 30 times that of the Sun and a surface temperature 6 times greater. Such stars emit prodigious amounts of high-energy ultraviolet radiation, and they are so luminous that their gravities can't prevent their outer atmospheres from being blown away in high-speed "stellar winds." As a result, such stars live fast and die young – this one is less than halfway through its total lifetime of about 4 million years. For comparison, the Sun is also a bit less than halfway through its lifetime of 10 billion years. Massive stars die in spectacular supernova explosions after their nuclear energy sources are depleted, whereas the Sun will have a more quiescent demise as first a red giant and then a white dwarf.
The ultraviolet radiation from the massive star causes the nebula to shine, while in combination with the wind it causes the nebula to expand. The fact that the star is not centered in the nebula shows that the expansion has encountered denser surrounding material toward the top and left. The densest region at left corresponds to the pillars imaged by Hubble. Here the dust and gas are being evaporated and dispersed by the energetic flows from the hot star; where there is a very dense condensation, a pillar is formed pointing toward the stellar energy source, because the condensation shields the material behind it. If the condensation is dense enough, rather than dissipating, it may be pushed to collapse into a new "triggered," "second-generation" star. Such an event is occurring in a pillar above center right as seen in the Hubble infrared image. It cannot be seen in the optical image, because those wavelengths are blocked by the pillar dust. However, the new star will eventually itself dissipate its dust cocoon and emerge to be seen in the optical.
As can be seen in the ground-based image, there are numerous small clusters within and just outside the large nebula, some with their own associated smaller nebulae. Some of them are very young and may also have been triggered by HD 42088, or otherwise formed spontaneously by different processes within the original large cloud. Recent detailed optical and infrared studies of this region from the ground have been led by the Indian astronomer J. Jose and are published in the Monthly Notices of the Royal Astronomical Society, volume 432, page 3445 (2013), and volume 424, page 2486 (2012).
Background Information: Hubble Trivia 2014
On April 24, 1990, the space shuttle Discovery lifted off from Earth with the Hubble Space Telescope nestled securely in its bay. The following day, Hubble was released into space, ready to peer into the vast unknown of space.
NASA's Hubble Space Telescope recently marked its 24th year in space, and to celebrate its 25th year, NASA is taking a look at some of the amazing statistics generated by the world-famous telescope.
Hubble has reinvigorated and reshaped our perception of space and uncovered a universe where almost anything seems possible within the laws of physics. Hubble has revealed properties of space and time that for most of human history were only probed in the imaginations of scientists and philosophers alike. Today, Hubble continues to provide views of cosmic wonders never before seen and is at the forefront of many new discoveries.
Shortly after Hubble was deployed in 1990, the observatory's primary mirror was discovered to have a flaw that affected the clarity of the telescope's early images. Astronauts repaired Hubble in December 1993. Including that trip, there have been five astronaut servicing missions to Hubble. The first servicing mission occurred Dec. 2-13, 1993. Subsequent servicing missions occurred on Feb. 11-21, 1997; Dec.19-27, 1999; March 1-12, 2002; and May 11-24, 2009.
Here are some statistics on the Hubble as of its 24th anniversary on April 24, 2014:
- Hubble captures pictures of stars, planets, and galaxies from its orbit around Earth while moving at 17,500 mph.
- Hubble has made more than 1 million observations since its mission began in 1990.
- Hubble has observed 38,000 celestial targets.
- Hubble has orbited Earth more than 3 billion miles along a circular, low Earth orbit of about 350 miles altitude.
- As of Hubble's 24th anniversary in April 2014, Hubble's observations have produced more than 100 terabytes of data.
- Hubble currently generates 844 gigabytes of data per month.
- About 4,000 astronomers from all over the world have used the telescope to probe the universe.
- Astronomers using Hubble data have published more than 11,000 scientific papers, making it one of the most productive scientific instruments ever built.
- Hubble weighs 24,500 pounds – as much as two full-grown elephants.
- Hubble's primary mirror is 2.4 meters (7 feet, 10.5 inches) across.
- Hubble is 13.3 meters (43.5 feet) long – the length of a large school bus.
The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, DC.
