57,296 research outputs found
NeIII/OII as an oxygen abundance indicator in the HII regions and HII galaxies
To calibrate the relationship between Ne3O2 (Ne3O2 =
log(\neiii/\oii)) and oxygen abundances, we present a
sample of 3000 \hii galaxies from the Sloan Digital Sky Survey (SDSS)
data release four. They are associated with a sample from the literature
intended to enlarge the oxygen abundance region. We calculated the electron
temperatures () of 210 galaxies in the SDSS sample with the direct method,
and of the other 2960 galaxies in SDSS sample calculated with an
empirical method. Then, we use a linear least-square fitting to calibrate the
Ne3O2 oxygen abundance indicator. It is found that the Ne3O2 estimator follows
a linear relation with \zoh\ that holds for the whole abundance range covered
by the sample, from approximately 7.0 to 9.0. The best linear relationship
between the Ne3O2 and the oxygen abundance is calibrated. The dispersion
between oxygen abundance and Ne3O2 index in the metal rich galaxies may come
partly from the moderate depletion of oxygen onto grains. The method
has the virtue of being single-valued and not affected by internal reddening.
As a result, the method can be a good metallicity indicator in the \hii
regions and \hii galaxies, especially in high-redshift galaxies.Comment: 7 pages, 6 figures. A&A accepte
The time-history of a satellite around an oblate planet
Time history of satellite around oblate plane
: An Excellent Candidate of Tetraquarks
We analyze various possible interpretations of the narrow state
which lies 100 MeV above threshold. This interesting state
decays mainly into instead of . If this relative branching
ratio is further confirmed by other experimental groups, we point out that the
identification of either as a state or more generally
as a state in the representation is probably
problematic. Instead, such an anomalous decay pattern strongly indicates
is a four quark state in the representation
with the quark content . We discuss its
partners in the same multiplet, and the similar four-quark states composed of a
bottom quark . Experimental searches of other members
especially those exotic ones are strongly called for
Anti-lecture Hall Compositions and Overpartitions
We show that the number of anti-lecture hall compositions of n with the first
entry not exceeding k-2 equals the number of overpartitions of n with
non-overlined parts not congruent to modulo k. This identity can be
considered as a refined version of the anti-lecture hall theorem of Corteel and
Savage. To prove this result, we find two Rogers-Ramanujan type identities for
overpartition which are analogous to the Rogers-Ramanjan type identities due to
Andrews. When k is odd, we give an alternative proof by using a generalized
Rogers-Ramanujan identity due to Andrews, a bijection of Corteel and Savage and
a refined version of a bijection also due to Corteel and Savage.Comment: 16 page
The Rogers-Ramanujan-Gordon Theorem for Overpartitions
Let be the number of partitions of with certain difference
condition and let be the number of partitions of with certain
congruence condition. The Rogers-Ramanujan-Gordon theorem states that
. Lovejoy obtained an overpartition analogue of the
Rogers-Ramanujan-Gordon theorem for the cases and . We find an
overpartition analogue of the Rogers-Ramanujan-Gordon theorem in the general
case. Let be the number of overpartitions of satisfying
certain difference condition and be the number of overpartitions
of whose non-overlined parts satisfy certain congruences condition. We show
that . By using a function introduced by Andrews, we
obtain a recurrence relation which implies that the generating function of
equals the generating function of . We also find a
generating function formula of by using Gordon marking
representations of overpartitions, which can be considered as an overpartition
analogue of an identity of Andrews for ordinary partitions.Comment: 26 page
Satellite motion for all inclinations around an oblate planet
Satellite motion for all inclinations around oblate plane
Weak-Light, Zero to -\pi Lossless Kerr-Phase Gate in Quantum-well System via Tunneling Interference Effect
We examine a Kerr phase gate in a semiconductor quantum well structure based
on the tunnelling interference effect. We show that there exist a specific
signal field detuning, at which the absorption/amplification of the probe field
will be eliminated with the increase of the tunnelling interference.
Simultaneously, the probe field will acquire a -\pi phase shift at the exit of
the medium. We demonstrate with numerical simulations that a complete 180^\circ
phase rotation for the probe field at the exit of the medium is achieved, which
may result in many applications in information science and telecommunication
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