A Spitzer Legacy Survey of the Cygnus-X Complex

Spitzer Proposal ID #40184 - 2007sptz.prop40184HWe propose a Spitzer Legacy Program to perform a uniform, unbiased survey of the Cygnus-X complex (~6x6 deg area) with IRAC and MIPS. This region contains the richest known concentration of massive protostars and the largest OB associations in the nearest 2 kpc. With this survey we can 1) analyze the evolution of high mass protostars with a large and statistically robust sample at a single distance, 2) study the role of clustering in high mass star formation, 3) study low mass star formation in a massive molecular cloud complex dominated by the energetics of ~100 O-stars, 4) assess what fraction of all young low mass stars in the nearest 2 kpc are forming in this one massive complex, and 5) provide an unbiased survey of the region and produce a legacy data set which can be used in conjunction with future studies of this region (e.g., with Herschel and JWST). The Cygnus-X survey will be an important step in constructing one of Spitzer's greatest legacies: surveying with high sensitivity and spatial resolution a representative sample of galactic star forming regions, from Bok globules to complexes containing millions of solar masses of gas and hundreds of O-stars

APerture Synthesis in the MID-Infrared with the VLTI

Our objective is to develop of the mid-infrared imaging for the VLTI. Several areas of astrophysics will benefit of this new capability. APreS-MIDI comprises a beam combiner which interfaces with the current MIDI instrument. It thus constitutes an extension to the two-beam interferometric instrument MIDI by increasing the number of recombined beams up to four. This extension provides better uv-coverage (6 visibility points measured in one set) and moreover will allow measurement of 4 closure phase relations thus providing for the first time aperture synthesis images in the mid-infrared spectral regime

Circumstellar Structure Around Evolved Stars in the Cygnus-X Spitzer Legacy Survey Region

Although the Cygnus-X region is primarily known as one of the richest massive star forming regions within 2 kpc, a large number of evolved objects also lie in, or at least along the line-of-sight to, the area observed by the Cygnus-X Spitzer Legacy Survey, including over 100 sources listed by Simbad as carbon stars, Wolf-Rayet stars, planetary nebulae, etc. Our Spitzer 24 micron images, made with the Multi-Band Imaging Photometer for Spitzer (MIPS), reveal previously undetected circumstellar emission from some of these objects. Emission at shorter wavelengths, observed using the Infrared Array Camera (IRAC), was also detected from some of the circumstellar structures, and a few were detected at longer wavelengths (MIPS 70 micron). Here, we present multi-wavelength Spizer images of the objects, including a bipolar nebula around a candidate carbon star BD +43 3710, a shell around the Wolf-Rayet candidate HBHA 4202-22, and a secondary shell around the luminous blue variable G79.29+0.46. In addition to the images, we combine near-infrared data from the 2 Micron All-Sky Survey (2MASS) with our Spitzer data to create spectral energy distributions for both the central objects and surrounding emission. Data from the Infrared Spectrograph (IRS) on Spitzer may also be discussed. We note that spiral structure has also been detected from a radio galaxy in our MIPS 24 micron data

Swift XRT observations of the breaking X-ray afterglow of GRB 050318

We report the results of Swift X-Ray Telescope (XRT) observations of GRB 050318. This event triggered the Burst Alert Telescope (BAT) aboard Swift and was followed-up with XRT and UVOT for 11 consecutive orbits starting from 54 min after the trigger. A previously unknown fading X-ray source was detected and accurately monitored. The source was found to decrease in intensity with time and a clear temporal break occurring at ~18 000 s after the trigger was observed. The X-ray light curve was found to be consistent with a broken power-law with decay indices -1.17± 0.08 and -2.10+0.22-0.24 before and after the break. The spectrum of the X-ray afterglow was well described by a photoelectrically absorbed power-law with energy index of -1.09±0.09. No evidence of spectral evolution was found. We compare these results with those obtained with UVOT and separately reported and refine the data analysis of BAT. We discuss our results in the framework of a collimated fireball model and a synchrotron radiation emission mechanism. Assuming the GRB redshift derived from the farthest optical absorption complex (z = 1.44), the event is fully consistent with the Ep-Eiso correlation