23,844 research outputs found
Faint star counts in the near-infrared
We discuss near-infrared star counts at the Galactic pole with a view to
guiding the NGST and ground-based NIR cameras. Star counts from deep K-band
images from the CFHT are presented, and compared with results from the 2MASS
survey and some Galaxy models. With appropriate corrections for detector
artifacts and galaxies, the data agree with the models down to K~18, but
indicate a larger population of fainter red stars. There is also a significant
population of compact galaxies that extend to the observational faint limit of
K=20.5. Recent Galaxy models agree well down to K19, but diverge at
fainter magnitudes.Comment: 14 pages and 4 diagrams; to appear in PAS
Retort braze bonding of borsic/aluminum composite sheet to titanium
Braze bonding studies between Borsic/aluminum composite and titanium sheet were conducted to establish acceptable brazing techniques and to assess potential joint efficiencies. Excellent braze joints were produced which exhibited joint strengths exceeding 117 MPa (17,000 psi) and which retained up to 2/3 of this strength at 589 K (600 F). Noticeable composite strength degradation resulting from the required high temperature braze cycle was found to be a problem
Perfect countably infinite Steiner triple systems
We use a free construction to prove the existence of perfect Steiner triple systems on a countably infinite point set. We use a specific countably infinite family of partial Steiner triple systems to start the construction, thus yielding 2â”0 non-isomorphic perfect systems
Observations of QSO J2233-606 in the Southern Hubble Deep Field
The Hubble Deep Field South (HDF-S) HST observations are expected to begin in
October 1998. We present a composite spectrum of the QSO in the HDF-S field
covering UV/optical/near IR wavelengths, obtained by combining data from the
ANU 2.3m Telescope with STIS on the HST. This intermediate resolution spectrum
covers the range 1600-10000A and allows us to derive some basic information on
the intervening absorption systems which will be important in planning future
higher resolution studies of this QSO.Comment: 9 pages and 2 figures, submitted to ApJ
Postcard: Kettler Furniture & Carpet Company, Pittsburg, Kansas
This color printed postcard features an illustration of a girl in a dress and apron with a feather duster in one hand and a miniature version of a stove in the other. She is standing next to a doll house and miniature furniture is lined up to go into the front door. A doll leans on the left side of the house and a black cat sits on top. Printed text is on the left and bottom of the card. A calendar month of March 1909 is on the top right corner. Typed text is on the back of the cardhttps://scholars.fhsu.edu/tj_postcards/1763/thumbnail.jp
The connection between metallicity and metal-line kinematics in (sub-)damped Lyman-alpha systems
A correlation between the metallicity, [M/H], and rest-frame MgII equivalent
width, EW, is found from 49 DLAs and strong sub-DLAs drawn from the literature
over the redshift range 0.2<z_abs<2.6. The correlation is significant at 4.2
sigma and improves to 4.7 sigma when the mild evolution of [M/H] with redshift
is taken into account. Even when including only the 26 DLAs (i.e. excluding
sub-DLAs) which have Zn metallicities and EW>0.7A, the correlation remains at
>3 sigma significance. Since the MgII2796 transition is predominantly saturated
in DLAs (which always have EW greater than 0.3A), EW is far more sensitive to
the kinematic spread of the metal velocity components across the absorption
profile than it is to [M/H]. Thus, the observed [M/H]--EW correlation points to
a strong link between the absorber metallicity and the mechanism for producing
and dispersing the velocity components. We also note that approximately half of
the 13 known molecular hydrogen absorbers have very high EW and very broad
velocity structures which show characteristics usually associated with
outflows. Follow-up ultraviolet- and blue-sensitive high-resolution spectra of
high-EW systems, initially identified in low-resolution spectra, may therefore
yield a large number of new H_2 discoveries.Comment: 9 pages, 2 figures (3 EPS files). Accepted by MNRA
X-ray sources and their optical counterparts in the globular cluster M 22
Using XMM-Newton EPIC imaging data, we have detected 50 low-luminosity X-ray
sources in the field of view of M 22, where 5 +/- 3 of these sources are likely
to be related to the cluster. Using differential optical photometry, we have
identified probable counterparts to those sources belonging to the cluster.
Using X-ray spectroscopic and timing studies, supported by the optical colours,
we propose that the most central X-ray sources in the cluster are cataclysmic
variables, millisecond pulsars, active binaries and a blue straggler. We also
identify a cluster of galaxies behind this globular cluster.Comment: 11 pages, 7 figures, accepted for publication in A&
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