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TOPIC: Antennae NGC4038/4039


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Antennae Galaxies
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New research on the Antennae Galaxies using the Advanced Camera for Surveys onboard the NASA/ESA Hubble Space Telescope shows that this benchmark pair of interacting galaxies is in fact much closer than previously thought - 45 million light-years instead of 65 million light-years.

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X-Ray Sources in the Antennae
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Title: Infrared Counterparts to Chandra X-Ray Sources in the Antennae
Authors: D.M. Clark, S.S. Eikenberry, B.R. Brandl, J.C. Wilson, J.C. Carson, C.P. Henderson, T. L. Hayward, D.J. Barry, A.F. Ptak, E.J.M. Colbert

We use deep J and Ks images of the Antennae (NGC 4038/9) obtained with WIRC on the Palomar 200-inch telescope, together with the Chandra X-ray source list of Zezas et al. (2002a), to search for IR counterparts to X-ray point sources. We establish an X-ray/IR astrometric frame tie with 0.5" rms residuals over a \~4.3' field. We find 13 ''strong'' IR counterparts brighter than Ks = 17.8 mag and < 1.0" from X-ray sources, and an additional 6 "possible'' IR counterparts between 1.0" and 1.5" from X-ray sources. The surface density of IR sources near the X-ray sources suggests only ~2 of the "strong'' counterparts and ~3 of the "possible'' counterparts are chance superpositions of unrelated objects.
Comparing both strong and possible IR counterparts to our photometric study of ~220 Antennae, IR clusters, we find the IR counterparts to X-ray sources are \~1.2 mag more luminous in Ks than average non-X-ray clusters. We also note that the X-ray/IR matches are concentrated in the spiral arms and ''overlap'' regions of the Antennae. This implies that these X-ray sources lie in the most ''super'' of the Antennae's Super Star Clusters, and thus trace the recent massive star formation history here. Based on the N_H inferred from the X-ray sources without IR counterparts, we determine that the absence of most of the ''missing'' IR counterparts is because they are intrinsically less luminous in the IR, implying that they trace a different (possibly older) stellar population.

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RE: Antennae NGC4038/4039
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This new NASA Hubble Space Telescope image of the Antennae galaxies in the constellation Corvus is the sharpest yet of this merging pair of galaxies 62 million light-years away. During the course of the collision, billions of stars will be formed. The brightest and most compact of these star birth regions are called super star clusters. The new image allows astronomers to better distinguish between the stars and super star clusters created in the collision of two spiral galaxies.

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Position (2000): R.A. 12h 01m 53s.18 Dec. -18 52' 52 ".4

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Posts: 131433
Date:
Antennae galaxies
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A new Hubble image of the Antennae galaxies is the sharpest yet of this merging pair of galaxies. As the two galaxies smash together, thousand of millions of stars are born, mostly in groups and clusters of stars.

Antennae_L
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Credit NASA

The Universe is an all-action arena for some of the largest, most slowly evolving and surprising processes known to mankind. A new picture taken by the Advanced Camera for Surveys (ACS), onboard the NASA/ESA Hubble Space Telescope, shows the best ever view of the Antennae galaxies - seemingly a violent clash between a pair of once isolated galaxies, but in reality a fertile marriage.

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Posts: 131433
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Antennae NGC4038/4039
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Title: Subarcsecond Resolution Mid-Infrared Observations of Super Star Clusters in the Antennae (NGC4038/4039)
Authors: Leonie Snijders, Paul P. van der Werf, Bernhard R. Brandl, Sabine Mengel, Daniel Schaerer, Zhong Wang

In this letter researchers present ground-based subarcsecond mid-infrared imaging and spectroscopy of young super star clusters in the overlap region of the merging galaxies NGC4038/4039 (the Antennae) obtained with the VLT Imager and Spectrometer for mid-Infrared (VISIR).
With its unprecedented spatial resolution VISIR begins to resolve the HII/PDR complexes around the star-forming regions for the first time. In the N-band spectra of two young star clusters unexpectedly low polycyclic aromatic hydrocarbon (PAH) emission is observed, compared to what is seen with the Infrared Space Observatory (ISO) and with the Spitzer Space Telescope. They conclude that a large fraction of the PAH emission cannot directly be associated with the super star clusters, but originate from an extended region of at least 215 pc radius around the clusters. In the distribution of (NeII) 12.81 micron emission a highly obscured cluster is discovered that does not have an optical or near-infrared counterpart.

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