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Pacman Nebula
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NGC 281 (also Pacman Nebula, IC 11, Sharpless 184 and OCL 313) is a magnitude +7.3 H II region located nearly 9,500 light-years away in the constellation Cassiopeia.

The nebula was first discovered by American astronomer Edward Emerson Barnard using a 12.7 cm (5 inch) refracting telescope at the Vanderbilt Observatory, Nashville, on the 16th November 1881

Position (2000): R.A. 00h 53m 04.59s, Dec. +56 38' 18.01"

It includes the open cluster IC 1590, the multiple star HD 5005, and several Bok globules. Colloquially, NGC 281 is also known as the Pacman Nebula for its resemblance to the video game character.
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IC 1590
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Title: Multiwavelength Study of NGC 281 Region
Authors: Saurabh Sharma, A. K. Pandey, J. C. Pandey, N. Chauhan, K. Ogura, D. K. Ojha, J. Borrissova, H. Mito, T. Verdugo, B. C. Bhatt

We present a multiwavelength study of the NGC 281 complex which contains the young cluster IC 1590 at the center, using deep wide-field optical UBVI_c photometry, slitless spectroscopy along with archival data sets in the near-infrared (NIR) and X-ray. The extent of IC 1590 is estimated to be ~6.5 pc. The cluster region shows a relatively small amount of differential reddening. The majority of the identified young stellar objects (YSOs) are low mass PMS stars having age <1-2 Myr and mass 0.5-3.5 solar masses. The slope (\Gamma) of the mass function for IC 1590, in the mass range 2 < M/solar masses \le 54, is found to be -1.110.15. The slope of the K-band luminosity function (0.370.07) is similar to the average value (~0.4) reported for young clusters. The distribution of gas and dust obtained from the IRAS, CO and radio maps indicates clumpy structures around the central cluster. The radial distribution of the young stellar objects, their ages, \Delta(H-K) NIR-excess, and the fraction of classical T Tauri stars suggest triggered star formation at the periphery of the cluster region. However, deeper optical, NIR and MIR observations are needed to have a conclusive view of star formation scenario in the region. The properties of the Class 0/I and Class II sources detected by using the Spitzer mid-infrared observations indicate that a majority of the Class II sources are X-ray emitting stars, whereas X-ray emission is absent from the Class 0/I sources. The spatial distribution of Class 0/I and Class II sources reveals the presence of three sub-clusters in the NGC 281 West region.

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Pacman nebula
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'Pacman' Nebula Gets Some Teeth

pia14873-640.jpg

To visible-light telescopes, this star-forming cloud appears to be chomping through the cosmos, earning it the nickname the "Pacman" nebula, like the famous Pac-Man video game that debuted in 1980. When viewed in infrared light by NASA's Wide-field Infrared Survey Explorer, or WISE, the Pacman takes on a new appearance. In place of its typical, triangle-shaped mouth is a new set of lower, sharp-looking teeth. The Pacman is located at the top of the picture, taking a bite in the direction of the upper left corner.
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RE: NGC281
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NGC 281

NGC281.jpg
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High-mass stars are important because they are responsible for much of the energy pumped into our galaxy over its lifetime. Unfortunately, these stars are poorly understood because they are often found relatively far away and can be obscured by gas and dust. The star cluster NGC 281 is an exception to this rule. It is located about 9,200 light years from Earth and, remarkably, almost 1,000 light years above the plane of the Galaxy, giving astronomers a nearly unfettered view of the star formation within it.

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Title: Distance to NGC 281 in a Galactic Fragmenting Superbubble: Parallax Measurements with VERA
Authors: Mayumi Sato, Tomoya Hirota, Mareki Honma, Hideyuki Kobayashi, Tetsuo Sasao, Takeshi Bushimata, Yoon Kyung Choi, Hiroshi Imai, Kenzaburo Iwadate, Takaaki Jike, Seiji Kameno, Osamu Kameya, Ryuichi Kamohara, Yukitoshi Kan-ya, Noriyuki Kawaguchi, Mi Kyoung Kim, Seisuke Kuji, Tomoharu Kurayama, Seiji Manabe, Makoto Matsui, Naoko Matsumoto, Takeshi Miyaji, Takumi Nagayama, Akiharu Nakagawa, Kayoko Nakamura, Chung Sik Oh, Toshihiro Omodaka, Tomoaki Oyama, Satoshi Sakai, Katsuhisa Sato, Katsunori M. Shibata, Yoshiaki Tamura, Kazuyoshi Yama****a

We have used the Japanese VLBI array VERA to perform high-precision astrometry of an H2O maser source in the Galactic star-forming region NGC 281 West, which has been considered to be part of a 300-pc superbubble. We successfully detected a trigonometric parallax of 0.3550.030 mas, corresponding to a source distance of 2.82+/-0.24 kpc. Our direct distance determination of NGC 281 has resolved the large distance discrepancy between previous photometric and kinematic studies; likely NGC 281 is in the far side of the Perseus spiral arm. The source distance as well as the absolute proper motions were used to demonstrate the 3D structure and expansion of the NGC 281 superbubble, ~650 pc in size parallel to the Galactic disk and with a shape slightly elongated along the disk or spherical, but not vertically elongated, indicating the superbubble expansion may be confined to the disk. We estimate the expansion velocity of the superbubble as ~20 km/s both perpendicular to and parallel to the Galactic disk with a consistent timescale of ~20 Myr.

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NGC 281 is a bustling hub of star formation about 10,000 light years away. This composite image of optical and X-ray emission includes regions where new stars are forming and older regions containing stars about 3 million years old.

ngc281560
Credit: X-ray: NASA/CXC/CfA/S.Wolk et al; Optical: NSF/AURA/WIYN/Univ. of Alaska/T.A.Rector
JPEG (400.5 kb) Tiff (6.8 MB) PS (6 MB)

The optical data (seen in red, orange, and yellow) show a small open cluster of stars, large lanes of obscuring gas and dust, and dense knots where stars may still be forming. The X-ray data (purple), based on a Chandra observation lasting more than a day, shows a different view. More than 300 individual X-ray sources are seen, most of them associated with IC 1590, the central cluster. The edge-on aspect of NGC 281 allows scientists to study the effects of powerful X-rays on the gas in the region, the raw material for star formation.

Position (J2000): RA 00h 52m 59.35s | Dec +56 37' 18.8"

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-- Edited by Blobrana at 18:32, 2007-11-16

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Bok globules
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The Hubble Space Telescope has photographed dense knots of dust and gas in our Milky Way Galaxy.


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This cosmic dust is a concentration of elements that are responsible for the formation of stars in our galaxy and throughout the universe.


Position (2000): R.A. 00h 53m 04s.59 Dec. +56 38' 18".01
This wide-field view of the star-forming region NGC 281 in the constellation Cassiopeia was taken with the WIYN telescope at Kitt Peak National Observatory near Tucson, Arizona.
Image NASA


The dark, opaque knots of gas and dust are called "Bok globules," and they are absorbing light in the centre of the nearby emission nebula and star-forming region, NGC 281.
The images were taken with Hubble's Advanced Camera for Surveys in October 2005.

NGC 281 is located nearly 9,500 light-years away in the direction of the constellation Cassiopeia.

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NGC 281
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NGC 281 is a star forming nebula about 2 degrees east of alpha Cassiopeia.
Prominent features include a small open cluster of stars, a diffuse red-glowing emission nebula, large lanes of obscuring gas and dust, and dense knots of dust and gas.

pacman_cannistra.jpg
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Position(2000): RA 00h 52m 48.0s Dec+56 37' 00"

The open cluster of stars IC1590 visible around the centre has formed only in the last few million years. The brightest member of this cluster is actually a multiple-star system shining light that helps ionise the nebula's gas, causing the red glow visible.
The lanes of dust visible left of centre are likely homes of future star formation. Particularly striking in the photograph are the dark Bok globules visible against the bright nebula.
The NGC 281 system lies about 5500 light years away.



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