Glenn Paul Tiede

The Frequency of Barred Spiral Galaxies in the Near-Infrared

We have determined the fraction of barred galaxies in the H-band for a statistically well-defined sample of 186 spirals drawn from the Ohio State University Bright Spiral Galaxy Survey. We find 56% of our sample to be strongly barred in the H band while another 16% is weakly barred. Only 27% of our sample is unbarred in the near-infrared. The RC3 and the Carnegie Atlas of Galaxies both classify only about 30% of our sample as strongly barred. Thus strong bars are nearly twice as prevalent in the near-infrared as in the optical. The frequency of genuine optically hidden bars is significant but lower than many claims in the literature: 40% of the galaxies in our sample that are classified as unbarred in the RC3 show evidence for a bar in the H band while the Carnegie Atlas lists this fraction as 66%. Our data reveal no significant trend in bar fraction as a function of morphology in either the optical or H band. Optical surveys of high-redshift galaxies may be strongly biased against finding bars, as bars are increasingly difficult to detect at bluer rest wavelengths.

THE INFRARED ARRAY CAMERA (IRAC) SHALLOW SURVEY

The Infrared Array Camera (IRAC) shallow survey covers 8.5 deg2 in the NOAO Deep Wide-Field Survey in Bootes with three or more 30 s exposures per position. An overview of the survey design, reduction, calibration, star-galaxy separation, and initial results is provided. The survey includes ≈370,000, 280,000, 38,000, and 34,000 sources brighter than the 5 σ limits of 6.4, 8.8, 51, and 50 μJy at 3.6, 4.5, 5.8, and 8 μm, respectively, including some with unusual spectral energy distributions.

Near-Infrared and Optical Morphology of Spiral Galaxies

We announce the initial release of data from the Ohio State University (OSU) Bright Spiral Galaxy Survey, a BVRJHK imaging survey of a well-defined sample of 205 bright, nearby spiral galaxies. We present H-band morphological classification on the Hubble sequence for the OSU Survey sample. We compare the H-band classification to B-band classification from our own images and from standard galaxy catalogs. Our B-band classifications match well with those of the standard catalogs. On average, galaxies with optical classifications from Sa through Scd appear about one T type earlier in the H band than in the B band, but with large scatter. This result does not support recent claims made in the literature that the optical and near-IR morphologies of spiral galaxies are uncorrelated. We present detailed descriptions of the H-band morphologies of our entire sample, as well as B- and H-band images for a set of 17 galaxies chosen as type examples and BRH color-composite images of six galaxies chosen to demonstrate the range in morphological variation as a function of wavelength.

From Stars to Superplanets: The Low-Mass Initial Mass Function in the Young Cluster IC 348

We investigate the low-mass population of the young cluster IC 348 down to the deuterium-burning limit, a —ducial boundary between brown dwarf and planetary mass objects, using a new and innovative method for the spectral classi—cation of late-type objects. Using photometric indices, constructed from HST /NICMOS narrowband imaging, that measure the strength of the 1.9 km water band, we determine the spectral type and reddening for every M-type star in the —eld, thereby separating cluster members from the interloper population. Due to the efficiency of our spectral classi—cation technique, our study is complete from D0.7 to The mass function derived for the cluster in this interval, dN/ 0.015 M _ . d log M P M0.5, is similar to that obtained for the Pleiades, but appears signi—cantly more abundant in brown dwarfs than the mass function for companions to nearby Sunlike stars. This provides compelling observational evidence for diUerent formation and evolutionary histories for substellar objects formed in isolation versus as companions. Because our determination of the IMF is complete to very low masses, we can place interesting constraints on the role of physical processes such as fragmentation in the star and planet formation process and the fraction of dark matter in the Galactic halo that resides in sub- stellar objects. Subject headings: stars: late-typestars: low-mass, brown dwarfs ¨ stars: luminosity function, mass functionstars: premain-sequence

Implications of New JHK Photometry and a Deep Infrared Luminosity Function for the Galactic Bulge

We present deep near-IR photometry for Galactic bulge stars in Baades Window,

MID-INFRARED SELECTION OF BROWN DWARFS AND HIGH-REDSHIFT QUASARS

(l,b) = (1.0\deg, -3.9\deg),

Red galaxy clustering in the NOAO deep wide-field survey

and another minor axis field at

Distances to Populous Clusters in the Large Magellanic Cloud via the K-band Luminosity of the Red Clump

(l,b) = (0^\circ,-6^\circ)

The Giant Branches of Open and Globular Clusters in the Infrared as Metallicity Indicators: A Comparison with Theory.

. We combine our data with previously published photometry and construct a luminosity function over the range

WIYN Open Cluster Study. XIX. Main-Sequence-Fitting Distances to Open Clusters Using V−K Color-Magnitude Diagrams*

5.5 \leq K_0 \leq 16.5