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TOPIC: Orion Nebula

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 RE: Orion Nebula Permalink Processed test capture of the orion nebula with a 100mm f5 Helios refractor and canon eos 350 prime focus. No filters. 10 seconds at ISO 1600Clear but Moonlight, twilight and light pollution.  Image was only roughly focused  __________________

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 Orion Proplyds Permalink Title: ALMA Observations of the Orion Proplyds Author: Rita K. Mann, James Di Francesco, Doug Johnstone, Sean M. Andrews, Jonathan P. Williams, John Bally, Luca Ricci, A. Meredith Hughes, Brenda C. Matthews We present ALMA observations of protoplanetary disks ("proplyds") in the Orion Nebula Cluster. We imaged 5 individual fields at 856um containing 22 HST-identified proplyds and detected 21 of them. Eight of those disks were detected for the first time at submillimeter wavelengths, including the most prominent, well-known proplyd in the entire Orion Nebula, 114-426. Thermal dust emission in excess of any free-free component was measured in all but one of the detected disks, and ranged between 1-163 mJy, with resulting disk masses of 0.3-79 Mjup. An additional 26 stars with no prior evidence of associated disks in HST observations were also imaged within the 5 fields, but only 2 were detected. The disk mass upper limits for the undetected targets, which include OB stars, theta1Ori C and theta1Ori F, range from 0.1-0.6 Mjup. Combining these ALMA data with previous SMA observations, we find a lack of massive (>3 Mjup) disks in the extreme-UV dominated region of Orion, within 0.03 pc of O-star theta1Ori C. At larger separations from theta1Ori C, in the far-UV dominated region, there is a wide range of disk masses, similar to what is found in low-mass star forming regions. Taken together, these results suggest that a rapid dissipation of disk masses likely inhibits potential planet formation in the extreme-UV dominated regions of OB associations, but leaves disks in the far-UV dominated regions relatively unaffected. Read more (2076kb, PDF) __________________

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 NGC 1976 Permalink NGC 1976 (also Messier 42, M42, LBN 974, Sharpless 281) is a magnitude +3 nebula located in the constellation Orion.  The nebula was discovered by Nicolas-Claude Fabri de Peiresc on the 24th November 1610. Right Ascension 05h 35m 17.1s, Declination -05° 23' 25" __________________

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Date:
 RE: Orion Nebula Permalink Title: Dynamical Evidence for a Magnetocentrifugal Wind from a 20 Msun Binary Young Stellar Object Authors: L. J. Greenhill, C. Goddi, C. J. Chandler, L. D. Matthews, E. M. L. Humphreys In Orion BN/KL, proper motions of 7 mm vibrationally-excited SiO masers trace rotation of a nearly edge-on disk and a bipolar wide-angle outflow 10-100 AU from radio Source I, a binary young stellar object (YSO) of ~20 solar masses. Here we map ground-state 7 mm SiO emission with the Very Large Array and track proper motions over 9 years. The innermost and strongest emission lies in two extended arcs bracketing Source I. The proper motions trace a northeast-southwest bipolar outflow 100-1000 AU from Source I with a median 3D motion of ~18 km/s. An overlying distribution of 1.3 cm H2O masers betrays similar flow characteristics. Gas dynamics and emission morphology traced by the masers suggest the presence of a magnetocentrifugal disk-wind. Reinforcing evidence lies in the colinearity of the flow, apparent rotation across the flow parallel to the disk rotation, and recollimation that narrows the flow opening angle ~120 AU downstream. The arcs of ground-state SiO emission may mark the transition point to a shocked super-Alfvenic outflow. Read more (2556kb, PDF) __________________

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 Orion Permalink Title: Discovery of Methyl Acetate and Gauche Ethyl Formate in Orion Authors: B. Tercero, I. Kleiner, J. Cernicharo, H. V. L. Nguyen, A. López, G. M. Muñoz Caro We report on the discovery of methyl acetate, CH3COOCH3, through the detection of a large number of rotational lines from each one of the spin states of the molecule: AA species (A1 or A2), EA species (E1), AE species (E2), EE species (E3 or E4). We also report the detection, for the first time in space, of the gauche conformer of ethyl formate, CH3CH2OCOH, in the same source. The trans conformer is also detected for the first time outside the galactic center source SgrB2. From the derived velocity of the emission of methyl acetate we conclude that it arises mainly from the compact ridge region with a total column density of (4.2±0.5)E15 cm(-2). The derived rotational temperature is 150 K. The column density for each conformer of ethyl formate, trans and gauche, is (4.5±1.0)E14 cm(-2). Their abundance ratio indicates a kinetic temperature of 135 K for the emitting gas and suggests that gas phase reactions could participate efficiently in the formation of both conformers in addition to cold ice mantle reactions on the surface of dust grains.Read more (167kb, PDF) __________________

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 Orion BN/KL Complex Permalink Title: Acetone in Orion BN/KL - High-resolution maps of a special oxygen-bearing molecule Authors: T.-C. Peng, D. Despois, N. Brouillet, A. Baudry, C. Favre, A. Remijan, A. Wootten, T. L. Wilson, F. Combes, G. Wlodarczak As one of the prime targets of interstellar chemistry study, Orion BN/KL clearly shows different molecular distributions between large nitrogen- (e.g., C2H5CN) and oxygen-bearing (e.g., HCOOCH3) molecules. However, acetone (CH3)2CO, a special complex O-bearing molecule, has been shown to have a very different distribution from other typical O-bearing molecules in the BN/KL region. We searched for acetone within our IRAM Plateau de Bure Interferometer 3 mm and 1.3 mm data sets. Twenty-two acetone lines were searched within these data sets. The angular resolution ranged from 1.8 x 0.8 to 6.0 x 2.3 arcsec^2, and the spectral resolution ranged from 0.4 to 1.9 km s-1. Nine of the acetone lines appear free of contamination. Three main acetone peaks (Ace-1, 2, and 3) are identified in Orion BN/KL. The new acetone source Ace-3 and the extended emission in the north of the hot core region have been found for the first time. An excitation temperature of about 150 K is determined toward Ace-1 and Ace-2, and the acetone column density is estimated to be 2-4 x 10^16 cm-2 with a relative abundance of 1-6 x 10^-8 toward these two peaks. Acetone is a few times less abundant toward the hot core and Ace-3 compared with Ace-1 and Ace-2. We find that the overall distribution of acetone in BN/KL is similar to that of N-bearing molecules, e.g., NH3 and C2H5CN, and very different from those of large O-bearing molecules, e.g., HCOOCH3 and (CH3)2O. Our findings show the acetone distribution is more extended than in previous studies and does not originate only in those areas where both N-bearing and O-bearing species are present. Moreover, because the N-bearing molecules may be associated with shocked gas in Orion BN/KL, this suggests that the formation and/or destruction of acetone may involve ammonia or large N-bearing molecules in a shocked-gas environment. Read more (7599kb, PDF) __________________

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 Orion A star-forming region Permalink Title: Transitional disks and their origins: an infrared spectroscopic survey of Orion A Authors: K. H. Kim, Dan M. Watson, P. Manoj, W. J. Forrest, Joan Najita, Elise Furlan, Benjamin Sargent, Catherine Espaillat, James Muzerolle, Tom Megeath, Nuria Calvet, Joel D. Green, Laura Arnold Transitional disks are protoplanetary disks around young stars, with inner holes or gaps which are surrounded by optically thick outer, and often inner, disks. Here we present observations of 62 new transitional disks in the Orion A star-forming region. These were identified using the Spitzer Space Telescope's Infrared Spectrograph and followed up with determinations of stellar and accretion parameters using the Infrared Telescope Facility's SpeX. We combine these new observations with our previous results on transitional disks in Taurus, Chamaeleon I, Ophiuchus and Perseus, and with archival X-ray observations. This produces a sample of 105 transitional disks of "cluster" age 3 Myr or less, by far the largest hitherto assembled. We use this sample to search for trends between the radial structure in the disks and many other system properties, in order to place constraints on the possible origins of transitional disks. We see a clear progression of host star accretion rate and the different disk morphologies. We confirm that transitional disks with complete central clearings have median accretion rates an order of magnitude smaller than radially continuous disks of the same population. Pre-transitional disks --- those objects with gaps that separate inner and outer disks --- have median accretion rates intermediate between the two. Our results from the search for statistically significant trends, especially related to $\dot{M}$, strongly support that in both cases the gaps are far more likely to be due to the gravitational influence of Jovian planets or brown dwarfs orbiting within the gaps, than to any of the photoevaporative, turbulent or grain-growth processes that can lead to disk dissipation. We also find that the fraction of Class II YSOs which are transitional disks is large, 0.1-0.2, especially in the youngest associations. Read more (1332kb, PDF) __________________

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 RE: Orion Nebula Permalink WISE Feels the Heat from Orion's SwordThe tangle of clouds and stars that lie in Orion's sword is showcased in a new, expansive view from NASA's Wide-field Infrared Survey Explorer, or WISE. Orion, the famous hunter, is visible in evening skies throughout the world from about December through April. The constellation appears tranquil and still to the naked eye, but lying in its sword, at what appears to be a slightly fuzzy star, is a turbulent cauldron of stellar birth. Read more __________________

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 Orion's Bullets Permalink Gemini telescope catches 'Orion's Bullets' An astronomical feature called "Orion's Bullets" has been imaged in stunning detail by a shape-shifting optical system on Hawaii's Gemini telescope.  The picture, unveiled at the 221st American Astronomical Society meeting in the US, demonstrates the power of what is called adaptive optics. It uses lasers shot skyward and mirrors that are changed in shape to perfectly image the lasers' spots on the sky. This undoes the effects of the Earth's atmosphere, making for sharper images. The Gemini telescope now has five of these "laser guide stars" and a new type of adaptive optics that provides a wider field of view. Read more __________________

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 RE: Orion Nebula Permalink Next-generation adaptive optics brings remarkable details to light in stellar nurseryA new image released today reveals how Gemini Observatory's most advanced adaptive optics (AO) system will help astronomers study the universe with an unprecedented level of clarity and detail by removing distortions due to the Earth's atmosphere. The photo, featuring an area on the outskirts of the famous Orion Nebula, illustrates the instrument's significant advancements over previous-generation AO systems.  Read more __________________
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