Boundary-Layer Similar Solutions for Equilibrium Dissociated Air and Application to the Calculation of Laminar Heat-Transfer Distribution on Blunt Bodies in High-Speed Flow

No abstract availabl

Apocope of Late Old Chinese short *ă: Early Central Asian loanword and Old Japanese evidence for Old Chinese disyllabic morphemes*

The morphophonology of Old Chinese has usually been reconstructed as an earlier version of the traditional reconstruction of Middle Chinese, with exclusively monosyllabic morphemes. For Old Chinese some scholars have posited syllabic morphemes with long or short vowels, or even polysyllabic morphemes, and other theories have been proposed, but it is still assumed that by Late Old Chinese any longer morphemes that once existed were already monosyllabic. However, Central Asian loans in Chinese suggest some disyllabic morphemes still existed in Late Old Chinese. They seem to be confirmed by a new study of little-noted Old Japanese transcriptions known as nigōgana. Thus the hitherto problematic Old Chinese and Old Japanese transcriptions of foreign words such as Saka and Buddha, and the monosyllabic theory of Old Chinese morphology, must be reconsidered. This paper’s new reconstructions conform to the data and have great implications for the reconstruction of Old Chinese as well as for the reconstruction of the early Chinese loans into Japanese

Constraints on the Space Density of Methane Dwarfs and the Substellar Mass Function from a Deep Near-Infrared Survey

We report preliminary results of a deep near-infrared search for methane-absorbing brown dwarfs; almost five years after the discovery of Gl 229b, there are only a few confirmed examples of this type of object. New J band, wide-field images, combined with pre-existing R band observations, allow efficient identification of candidates by their extreme (R-J) colours. Follow-up measurements with custom filters can then confirm objects with methane absorption. To date, we have surveyed a total of 11.4 square degrees to J~20.5 and R~25. Follow-up CH_4 filter observations of promising candidates in 1/4 of these fields have turned up no methane absorbing brown dwarfs. With 90% confidence, this implies that the space density of objects similar to Gl 229b is less than 0.012 per cubic parsec. These calculations account for the vertical structure of the Galaxy, which can be important for sensitive measurements. Combining published theoretical atmospheric models with our observations sets an upper limit of alpha <= 0.8 for the exponent of the initial mass function power law in this domain.Comment: 11 pages + 2 figures To be published in Astrophysical Journal Letter

Improved Si:As BIBIB (Back-Illuminated Blocked-Impurity-Band) hybrid arrays

Results of a program to increase the short wavelength (less than 10 microns) detective quantum efficiency, eta/beta, of Si:As Impurity Band Conduction arrays are presented. The arrays are epitaxially grown Back-Illuminated Blocked (BIB) Impurity-Band (BIBIB) 10x50 detectors bonded to switched-FET multiplexers. It is shown that the 4.7 microns detective quantum efficiency increases proportionately with the thickness of the infrared active layer. A BIB array with a thick active layer, designed for low dark current, exhibits eta/beta = 7 to 9 percent at 4.7 microns for applied bias voltages between 3 and 5 V. The product of quantum efficiency and photoelectric gain, etaG, increases from 0.3 to 2.5 as the voltage increases from 3 to 5 V. Over this voltage range, the dark current increases from 8 to 120 e(-)s(-1) at a device temperature of 4.2 K and is under 70 e(-)s(-1) for all voltages at 2 K. Because of device gain, the effective dark current (equivalent photon rate) is less than 3 e(-)s(-1) under all operating conditions. The effective read noise (equivalent photon noise) is found to be less than 12 electrons under all operating conditions and for integration times between 0.05 and 100 seconds

A faint red stellar halo around an edge-on disc galaxy in the Hubble Ultra Deep Field

We analyse the detailed structure of a highly-inclined (i>~80 degrees) disc galaxy which lies within the Hubble Ultra Deep Field (UDF). The unprecedented depth of the UDF data allow disc and extraplanar emission to be reliably traced to surface brightness levels of mu_{V,i,z}~29-30 mag/arcsec^2 (corresponding to rest-frame equivalents of mu_{g,r,i}~28-29 mag/arcsec^2) in this redshift z=0.32 system. We detect excess emission above the disc which is characterised by a moderately-flattened (b/a~0.6) power-law (I proportional to R^(-2.6)). The structure and colour of this component are very similar to the stellar halo detected in an SDSS stacking analysis of local disc galaxies (Zibetti, White and Brinkmann 2004) and lend support to the idea that we have detected a stellar halo in this distant system. Although the peculiar colours of the halo are difficult to understand in terms of normal stellar populations, the consistency found between the UDF and SDSS analyses suggests that they cannot be easily discounted.Comment: 5 pages, 5 figures, accepted for publication in MNRAS Letters. Figure 1 substantially degraded, full resolution version available at http://www.mpa-garching.mpg.de/~zibetti/UDFhalo.pd

Critical Protoplanetary Core Masses in Protoplanetary Disks and the Formation of Short-Period Giant Planets

We study a solid protoplanetary core of 1-10 earth masses migrating through a disk. We suppose the core luminosity is generated as a result of planetesimal accretion and calculate the structure of the gaseous envelope assuming equilibrium. This is a good approximation when the core mass is less than the critical value, M_{crit}, above which rapid gas accretion begins. We model the structure of the protoplanetary nebula as an accretion disk with constant \alpha. We present analytic fits for the steady state relation between disk surface density and mass accretion rate as a function of radius r. We calculate M_{crit} as a function of r, gas accretion rate through the disk, and planetesimal accretion rate onto the core \dot{M}. For a fixed \dot{M}, M_{crit} increases inwards, and it decreases with \dot{M}. We find that \dot{M} onto cores migrating inwards in a time 10^3-10^5 yr at 1 AU is sufficient to prevent the attainment of M_{crit} during the migration process. Only at small radii where planetesimals no longer exist can M_{crit} be attained. At small radii, the runaway gas accretion phase may become longer than the disk lifetime if the core mass is too small. However, massive cores can be built-up through the merger of additional incoming cores on a timescale shorter than for in situ formation. Therefore, feeding zone depletion in the neighborhood of a fixed orbit may be avoided. Accordingly, we suggest that giant planets may begin to form early in the life of the protostellar disk at small radii, on a timescale that may be significantly shorter than for in situ formation. (abridged)Comment: 24 pages (including 9 figures), LaTeX, uses emulateapj.sty, to be published in ApJ, also available at http://www.ucolick.org/~ct/home.htm