2,115 research outputs found
Amplitude variability and multiple frequencies in 44 Tau: 2000 - 2006
This study has three principal aims: (i) to increase the number of detected
pulsation modes of 44 Tau, especially outside the previously known frequency
ranges, (ii) to study the amplitude variability and its systematics, and (iii)
to examine the combination frequencies.
During the 2004/5 and 2005/6 observing seasons, high-precision photometry was
obtained with the Vienna Automatic Photoelectric Telescope in Arizona during 52
nights. Together with previous campaigns, a data base from 2000 to 2006 was
available for multifrequency analyses.
Forty-nine pulsation frequencies are detected, of which 15 are independent
pulsation modes and 34 combination frequencies or harmonics. The newly found
gravity mode at 5.30 c/d extends the known frequency range of instability.
Strong amplitude variability from year to year is found for the \ell = 1 modes,
while the two radial modes have essentially constant amplitudes. Possible
origins of the amplitude variability of the \ell = 1 modes, such as precession
of the pulsation axis, beating and resonance effects are considered. The
amplitudes of the combination frequencies, f_i + f_j, mirror the variations in
the parent modes. The combination parameter, which relates the amplitudes of
the combination frequencies to those of the parent modes, is found to be
different for different parents.Comment: 10 pages, 8 figures, 4 tables, accepted for publication in A&
Defending Defenders: Remarks on Nichol and Pierce
Both Nichol and Pierce, as devotees of grand theory, are interested in analyzing Scalia\u27s agenda, however described. They view Defenders as a fundamental change in the Court\u27s standing jurisprudence, in part because of the symbolism they and their fellow detractors impart to the decision. In contrast, the author is apparently a miniaturist, at least when it comes to the possibility of grand theories and broader agendas. Like Justice Kennedy, the author does not read Justice Scalia\u27s opinion to hold that Congress cannot confer standing by defining an injury and relating it to a class of persons entitled to sue
Introductory Remarks
In the interpretation of any statute, there are at least three sources of understanding one can look to: the text, the legislators who penned it, and the judges who interpret it. The methodological problem for lawyers is how to make use of each source of knowledge in attempting to know the law. Judges Abner Mikva and Kenneth Starr, both from the United States Court of Appeals for the District of Columbia Circuit, join issue in the following debate about the correct weight, if any, to give to legislative history in interpreting a statute\u27s meaning
Asteroseismology with the WIRE satellite
I give a summary of results from the WIRE satellite, which has been used to
observe bright stars from 1999-2000 and 2003-2006. The WIRE targets are
monitored for up to five weeks with a duty cycle of 30-40%. The aim has been to
characterize the flux variation of stars across the Hertzsprung-Russell
diagram. I present an overview of the results for solar-like stars, delta Scuti
stars, giant stars, and eclipsing binaries.Comment: Accepted for publication in CoAst. Proceedings of the Vienna Workshop
on the Future of Asteroseismology (September 2006). 8 pages, 2 figure
Equidistant frequency triplets in pulsating stars: The Combination Mode Hypothesis
Multiplet structures are a common feature in pulsating stars, and can be the
consequence of rotational splitting, mode interaction or sinusoidal amplitude
variations. In this paper we examine the phenomenon of (nearly) equidistant
triplets, which are unlikely to be caused by rotational splitting, in different
types of pulsating stars: a Delta Scuti variable (1 Mon), an RR Lyrae variable
(RR Lyr) and a short-period Cepheid (V743 Lyr). We examine the hypothesis that
one of the modes forming the triplet results from a combination of the other
two modes. The analyses were carried out on recent data sets by using
multiple-frequency analyses and statistics with the package PERIOD04. In
particular, the small departures from equidistance were calculated for the
three selected stars. For the Delta Scuti variable 1 Mon, the departure from
equidistance is only 0.000079 +- 0.000001 c/d (or 0.91 +- 0.01 nHz). For 1 Mon
the Combination Mode Hypothesis with a mode excited by resonance is the most
probable explanation. For the star RR Lyr, the hypothesis of resonance through
a combination of modes should be considered. The results for the best-studied
cepheid with a Blazhko period (V743 Lyr) are inconclusive because of an
unfavorable period of 1.49d and insufficient data.Comment: 6 pages, 1 figure, accepted for publication in Astronomy and
Astrophysic
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