8 research outputs found
Quantum virial expansion approach to thermodynamics of He adsorbates in carbon nanotube materials: Interacting Bose gas in one dimension
I demonstrate that He adsorbates in carbon nanotube materials can be
treated as one-dimensional interacting gas of spinless bosons for temperatures
below 8 K and for coverages such that all the adsorbates are in the groove
positions of the carbon nanotube bundles. The effects of adsorbate-adsorbate
interactions are studied within the scheme of virial expansion approach. The
theoretical predictions for the specific heat of the interacting adsorbed gas
are given.Comment: 5 PS figure
Substructure revealed by RR Lyraes in SDSS Stripe 82
We present an analysis of the substructure revealed by 407 RR Lyraes in Sloan
Digital Sky Survey (SDSS) Stripe 82. Period estimates are determined to high
accuracy using a string-length method. A subset of 178 RR Lyraes with
spectrally derived metallicities are employed to derive
metallicity-period-amplitude relations, which are then used to find
metallicities and distances for the entire sample. The RR Lyraes lie between 5
and 115 kpc from the Galactic center. They are divided into subsets of 316 RRab
types and 91 RRc types based on their period, colour and metallicity. The
density distribution is not smooth, but dominated by clumps and substructure.
Samples of 55 and 237 RR Lyraes associated with the Sagittarius Stream and the
Hercules-Aquila Cloud respectively are identified. Hence, ~ 70 % of the RR
Lyraes in Stripe 82 belong to known substructure. There is a sharp break in the
density distribution at Galactocentric radii of 40 kpc, reflecting the fact
that the dominant substructure in Stripe 82 - the Hercules-Aquila Cloud and the
Sagittarius Stream - lies within 40 kpc. In fact, almost 60 % of all the RR
Lyraes in Stripe 82 are associated with the Hercules-Aquila Cloud alone, which
emphasises its pre-eminence. Additionally, evidence of a new and distant
substructure - the Pisces Overdensity - is found, consisting of 28 faint RR
Lyraes centered on Galactic coordinates (80 deg, -55 deg) and with distances of
~ 80 kpc. The total stellar mass in the Pisces Overdensity is ~10000 solar
masses and its metallicity is [Fe/H] ~ -1.5.Comment: 15 pages, submitted to MNRA
Some Energy Inequalities for Two-Body Problems and Helium Dimer
It is shown that the energy of two particles in 2D (2 dimensions) is always less or equal than energy in 1D, and the energy in 3D can be less or greater than in 2D. The application to the important case of helium 4 dimer shows that this molecule may have only in 2D at least one bound excited stat