1,984 research outputs found
Multichannel cold collisions between metastable Sr atoms
We present a multichannel scattering calculation of elastic and inelastic
cold collisions between two low-field seeking, metastable ^{88}Sr [(5s5p)
^3P_2] atoms in the presence of an external magnetic field. The scattering
physics is governed by strong anisotropic long-range interactions, which lead
to pronounced coupling among the partial waves of relative motion. As a result,
nonadiabatic transitions are shown to trigger a high rate of inelastic losses.
At relatively high energies, T > 100 mkK, the total inelastic collision rate is
comparable with the elastic rate. However, at lower collisional energy, the
elastic rate decreases, and at T ~ 1mkK, it becomes substantially smaller than
the inelastic rate. Our study suggests that magnetic trapping and evaporative
cooling of ^{88}Sr [(5s5p) ^3P_2] atoms, as well as ^{40}Ca [(4s4p) ^3P_2], in
low-field seeking states will prove difficult to achieve experimentally.Comment: 4 pages, Latex, Submitte
A combined spectroscopic and photometric stellar activity study of Epsilon Eridani
We present simultaneous ground-based radial velocity (RV) measurements and
space-based photometric measurements of the young and active K dwarf Epsilon
Eridani. These measurements provide a data set for exploring methods of
identifying and ultimately distinguishing stellar photospheric velocities from
Keplerian motion. We compare three methods we have used in exploring this data
set: Dalmatian, an MCMC spot modeling code that fits photometric and RV
measurements simultaneously; the FF method, which uses photometric
measurements to predict the stellar activity signal in simultaneous RV
measurements; and H analysis. We show that our H measurements
are strongly correlated with photometry from the Microvariability and
Oscillations of STars (MOST) instrument, which led to a promising new method
based solely on the spectroscopic observations. This new method, which we refer
to as the HH method, uses H measurements as input into the FF
model. While the Dalmatian spot modeling analysis and the FF method with
MOST space-based photometry are currently more robust, the HH method only
makes use of one of the thousands of stellar lines in the visible spectrum. By
leveraging additional spectral activity indicators, we believe the HH method
may prove quite useful in disentangling stellar signals
Managing digital assets on death and disability: An examination of the determinants of digital asset planning literacy
Despite its increasing importance, digital financial literacy (DFL) is yet to be adequately understood. This article reports on one aspect of DFL, namely, digital asset planning literacy (DAPL) which is an individual’s awareness of what happens to their digital assets on their death or incapacity. Our results from Australia and Singapore suggest that single, less-educated women are less likely to possess DAPL, and that the number of digital assets is negatively associated with DAPL, while having a Will is positively related to DAPL. With this study, we put forward that financial education should include consumer rights regarding digital financial assets. JEL Classification: D14; G53; G50; J12; J1
HI Properties of Low Luminosity Star-Forming Galaxies in the KPNO International Spectroscopic Survey
New HI observations are presented for a complete sample of 109 low luminosity
star-forming galaxies taken from the KPNO International Spectroscopic Survey
(KISS), the first CCD-based wide-field objective-prism survey for emission-line
galaxies. This sample consists of all star-forming galaxies with M_B > -18.0
and cz < 11,000 km/s from the first Halpha-selected survey list. Overall, 97
out of 109 galaxies have been detected in HI. We confirm the weak trend of
increasing gas richness with decreasing luminosity found by previous authors.
Gas richness is also shown to be weakly anti-correlated with metallicity. The
dependence of star formation rates (SFRs) and HI gas depletion timescales on
metallicity is examined. The median solar metallicity based SFR and gas
depletion timescale are 0.1639 M_sun/yr and 5 Gyrs, respectively. Corrections
for variations in metallicity decreases SFRs by about 0.5 dex and increases gas
depletion timescales by an average of about 8 Gyrs. The majority of galaxies in
this sample still have large reservoirs of HI gas, and despite their large
current star formation rates, could have formed stars in a quasi-continuous
manner for a Hubble time. Finally, we present the first HI mass function for
low luminosity star-forming galaxies and show that this subpopulation
contributes 10-15% of the overall HI density in the local universe. We conclude
that if the HI mass function of the Universe does indeed have a steeply rising
low-mass slope as suggested by previous authors, it is not due to the
population of low luminosity star-forming galaxies.Comment: 27 pages, 13 figures, 4 tables. Accepted for publication in the
Astronomical Journa
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