arXiv subjects

J. L. Pipher

Publications and source records attributed to J. L. Pipher.

23 records · Page 2Linked to original sources

arXiv2004

The IRAC Shallow Survey

The IRAC shallow survey covers 8.5 square degrees in the NOAO Deep Wide-Field Survey in Bootes with 3 or more 30 second exposures per position. An overview of the survey design, reduction, calibration, star-galaxy separation, and initial results is provided. The survey includes approximately 370,000, 280,000, 38,000, and 34,000 sources brighter than the 5 sigma limits of 6.4, 8.8, 51, and 50 microJy at 3.6, 4.5, 5.8, and 8 microns respectively, including some with unusual spectral energy distributions.

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arXiv2004

The NGC 7129 Young Stellar Cluster: A Combined Spitzer, MMT, and 2MASS Census of Disks, Protostars, and Outflows

We present the analysis of seven band (1.2 to 8 micron) ground and space-based imaging of the NGC 7129 young stellar cluster from FLAMINGOS on MMT, 2MASS, and the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. An analysis of the H-[4.5] vs. J-H colors reveals 84 objects with circumstellar disks. Of these, 42 are located within the cluster core, a 0.5 pc (100'') radius region of enhanced stellar surface density. From a luminosity and extinction limited sample of the stars within the cluster core boundary we have determined that 54% +/- 14% have circumstellar disks. Finally, we report the detection of several resolved outflows in the IRAC 4.5 micron mosaic.

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arXiv2004

The 24-Micron View of Embedded Star Formation in NGC 7129

We present observations of the star formation region NGC 7129 taken with the Multiband Imaging Photometer for Spitzer (MIPS). A significant population of sources, likely pre-main sequence members of the young stellar cluster, is revealed outside the central photoionization region. Combining with Infrared Array Camera (IRAC) and ground-based near-infrared images, we have obtained colors and spectral energy distributions for some 60 objects. The [3.6]-[4.5] vs. [8]-[24] color-color plane shows sources clustered at several different loci, which roughly correspond to the archetypal evolutionary sequence Class 0, I, II, and III. We obtain preliminary classifications for 36 objects, and find significant numbers of both Class I and II objects. Most of the pre-main sequence candidates are associated with the densest part of the molecular cloud surrounding the photoionization region, indicating active star formation over a broad area outside the central cluster. We discuss three Class II candidates that exhibit evidence of inner disk clearing, which would be some of the youngest known examples of a transition from accretion to optically thin quiescent disks.

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arXiv2004

Initial Results from The Spitzer Young Stellar Cluster Survey

We report initial results from IRAC observations of four young stellar clusters. These regions are part of a larger Spitzer survey of 31 young stellar groups and clusters within 1 kpc of the Sun. In each of the four clusters, there are between 39 and 85 objects with colors inconsistent with reddened stellar photospheres. We identify these objects as young stars with significant emission from circumstellar dust. Applying an analysis developed in a companion paper (Allen et al. 2004), we classify these objects as either pre-main sequence stars with disks (class II) or protostellar objects (class I). These show that the sites of recent star formation are distributed over multi-parsec size scales. In two clusters, Cepheus C and S140, we find protostars embedded in filamentary dark clouds seen against diffuse emission in the IRAC bands.

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arXiv2000

Validation of Up-the-Ramp Sampling with Cosmic Ray Rejection on IR Detectors

We examine cosmic ray rejection methodology on data collected from InSb and Si:As detectors. The application of an Up-the-Ramp sampling technique with cosmic ray identification and mitigation is the focus of this study. This technique is valuable for space-based observatories which are exposed to high-radiation environments. We validate the Up-the-Ramp approach on radiation-test data sets with InSb and Si:As detectors which were generated for SIRTF. The Up-the-Ramp sampling method studied in this paper is over 99.9% effective at removing cosmic rays and preserves the structure and photometric quality of the image to well within the measurement error.

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