The infrared-excess sample that enters the MPCM catalog is thus biased toward clustered groups of infrared-excess sources, and is less sensitive to widely dispersed populations. The shell is approximately 5 kpc away from the centre of the galaxy, proving that it has been recently formed. Known as an emission nebula since the 18th century, it was the site where Merle Walker first described stars during their pre-main sequence phase during the s Dahm a. Two mechanisms, blending and extinction partially embedded phase can remove objects in this region. This section is limited to a qualitative examination of multiwavelength images of the prototype clusters before quantitative MYStIX analysis has taken place. In classifying X-ray sources as young stars or one of three populations of contaminants, we calculate a probability for each class based on several source properties and apply an arbitrary decision rule to make the class assignment Broos et al.

Uploader: Zulugrel
Date Added: 21 August 2007
File Size: 49.48 Mb
Operating Systems: Windows NT/2000/XP/2003/2003/7/8/10 MacOS 10/X
Downloads: 36254
Price: Free* [*Free Regsitration Required]

Some statistical technique, such as our probability scaled to K -band magnitudes Naylor et al. Most of the X-ray images have been studied in the past, some in considerable detail.

Therefore, we consider that the age for most of the clusters observed in the RIH bands can be trusted.

In bold are the final age, mass and extinction assigned to the clusters. Systematic uncertainties can be larger than internal uncertainties for each distance estimation method.

The near-IR image has much reduced nebulosity, but the dense stellar pattern is nearly uniform across the field upper right panel. ObsIDs Column 2 gives the observation identifiers. Using plots as the ones shown in Fig.


We have, for the first time in this galaxy, detected a shell structure 8. CFRs during the last 40 Myr of starburst activity. Sztar 6 right panel shows the result of its application to the crowded Trifid Nebula region; if the infrared source closest to an X-ray source is faint, it may be rejected as the true counterpart in favor of a more distant, but brighter, source.

1PC-SATAR Expansion Board – Computing History

As historical positions of OB stars often do not have the subarcsecond accuracy needed for MYStIX analysis, we use positions from our near-infrared catalog. We find several hundred luminous star clusters which we analyse by means of SED fitting using state of the art models including nebular gas emission. Clusters that do sattar show any red excess are represented with filled black dots. The MYStIX project also takes a particular approach to statistical decision making known as “soft classification.

This massive star-forming complex contains at least two major clusters, both prominent in X-rays Townsley et al.

Tr 15 appears yet older and appears to have lost its most massive stars as supernovae Wang et al. The other curves are derived from simulations of contaminating populations Getman satarr al. The embedded cluster shows a plume of hot X-ray-emitting plasma just breaking through the edge of its giant molecular cloud; this outflow may be similar to that seen in M 17, but with a less convenient face-on orientation and earlier in its evolution Townsley et al.

donate to us!

Mass segregation is present. More objects are included in Appendix A Fig.

But the spectroscopic sample of Forbrich et al. Many clusters show a spread in apparent ages in the Hertzsprung—Russell diagram HRDbut the interpretation of this effect is debated Baraffe et al.


The final source list is constructed iteratively in the original image of photon events based on a statistical significance level that a source exists above a local Poisson background.

It is clear that self-consistent stellar and nebular evolutionary models are not enough to interpret the NIR luminosity properties of these clusters and other mechanisms need to be addressed see Section 4 of this work and section 5 in Adamo et al.

Clusters with only IR excess i. X-ray, near-IR, and mid-IR. It does not have a monolithic cluster structure, but rather appears to be a collection of 2—3 clusters with additional distributed young stars. Here, we performed the same exercise using the set of filters available for ESO Is the initial mass function IMF constant during cluster formation both spatial and temporal Krumholz et al.

The panel the bottom left-hand side shows clusters in the age range 20— Myr. Several clusters are located between the central region and the shell.


Its pre-main sequence membership is poorly established with no study in the visible band. To address this challenge in classifying MYStIX sources, we build upon the statistical classifier for X-ray sources developed by Broos et al. The sample cannot be used staar count how many Galactic clusters have high or low values of a given property or how many star-forming regions fall into a given class.