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Bow-Tie Nebula
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NGC 40

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Caldwell 2
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NGC 40 (also known as the Bow-Tie Nebula, PK 120+9.1, 2MASS J00130099 + 7231190, and Caldwell 2) is a magnitude +10.7 planetary nebula located 3000 - 4600 light-years away in the constellation Cepheus.
The magnitude of the central star HD 826 is +11.5
The age of NGC 40 is estimated to be about 4,500 years, with its gas clouds still expanding at about 29 km/s. The nebula spans about 1 light-year across.

The planetary nebula was discovered by the German-British astronomer William Herschel using a 47.5 cm (18.7 inch) f/13 speculum reflector at Windsor Road, Slough, on the 25th November 1788.

Right Ascension 0h 13m 1.0s, Declination +72 31' 19"

Under dark skies, NGC 40 can be spotted with 100mm (4-inch) telescopes appearing as an out of focus star tucked away between two 9th magnitude stars. With an apparent magnitude of +10.7 and spanning just 36 arc seconds in diameter
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About 30,000 years from now, scientists theorize that NGC 40 will fade away, leaving only a white dwarf star approximately the size of Earth
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RE: NGC40
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This composite X-ray (blue)/optical (red) image of the object NGC 40 in the constellation Cepheus, shows hot gas around a dying, Sun-like star.
NGC 40, also known as the Bow Tie Nebula, is one of a class of objects called planetary nebulas, so-called because they look like the disk of a planet when viewed with a small telescope.


Position(2000) RA 00h 13m 01.00s Dec +72 31' 19.00"

Planetary nebulas provide a preview of how our Sun may look about five billion years from now when most of its nuclear fusion energy sources will have been used up. The star has puffed off its outer layer to leave behind a smaller, hot star with a surface temperature of about 50,000 degrees Celsius.

Radiation from the hot star heats the ejected matter to about 10,000 degrees to produce the complex and graceful nebula (red) about a light year across.
The X-rays in the composite image reveal a shell of multimillion degree gas (blue) that has been compressed and heated by a 2-million-miles-per-hour stellar wind from the dying star.

The discovery of hot X-ray emitting clouds of gas within planetary nebulas such as NGC 40 enables astronomers to study the violent demise of Sun-like stars.
By observing many planetary nebulas, astronomers hope to be able to determine whether X-ray-emitting clouds represent a short-lived phase of most dying stars or unusually violent conditions within specific planetary nebulas.

In another 30,000 years or so, NGC 40 that lies about 3,000 light years, will fade away, leaving behind a compact, ultra dense white dwarf star about the size of Earth. It is estimated that about one planetary nebula is formed in the Galaxy every year, and that they recycle about one solar mass of helium-enriched material back into the Galaxy per year.


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NGC 40
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Two astronomers have used NASA's Chandra X-ray Observatory to discover a shell of superheated gas around a dying star in the Milky Way galaxy.

Joel Kastner, professor of imaging science at the Rochester Institute of Technology, and Rodolpho Montez, a graduate student in physics and astronomy at the University of Rochester, will present their results today at the American Astronomical Society meeting in Minneapolis. Their discovery shows how material ejected at two million miles per hour during the final, dying stages of sun-like stars can heat previously ejected gas to the point where it will emit X-rays. The study also offers new insight into how long the ejected gas around dying stars can persist in such a superheated state.



According to Kastner, the hot gas shows up in high-resolution Chandra X-ray images of the planetary nebula NGC 40, which is located about 3,000 light years away from Earth in the direction of the constellation Cepheus.

"Planetary nebulae are shells of gas ejected by dying stars. They offer astronomers a forecast of what could happen to our own sun about five billion years from now--when it finally exhausts the reservoir of hydrogen gas at its core that presently provides its source of nuclear power." - Joel Kastner
In his research, Montez discovered the X-ray emitting shell in NGC 40 by generating an image that uses only specific energy-selected X-rays--revealing a ring of superheated gas that lies just within the portions of the nebula that appear in optical and infrared images.

"This hot bubble of gas vividly demonstrates how, as a planetary nebula forms, the gas ejection process of the central, dying star becomes increasingly energetic. Mass ejection during stellar death can result in violent collisions that can heat the ejected gas up to temperatures of more than a million degrees." - Joel Kastner

The detection of X-rays from NGC 40 adds to a growing list of such discoveries by Chandra and its European counterpart, the XMM-Newton X-ray satellite observatory. Kastner and Montez (along with collaborators Orsola de Marco, of the American Museum of Natural History in New York, and Noam Soker, of the Technion Institute in Haifa, Israel) have studied these previous X-ray observations of planetary nebulae, and find that the X-ray and infrared output of such objects is closely coupled.

"The connection between X-ray and infrared emission seems to show that the hot bubble phase is restricted to early times in stellar death, when a planetary nebula is quite young and the dust within it is still relatively warm," - Rodolpho Montez .
The correspondence indicates that the production of superheated gas is a short-lived phase in the life of a planetary nebula, although Kastner cautions that additional Chandra and XMM-Newton observations are required to test this idea.

PHOTOS AVAILABLE:

NGC40_montage
NGC40 red
NGC40 bw - red (400kb)


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