52 research outputs found
Paper Session I-C - CORABI - The Impact of the University on Corporate, Regional, and State Commercial Space Development
Studies and Recommendations for Bilateral Action
• Florida Governor\u27s Commission on Space
• National Academy of Sciences
• Business Higher Education Forum
• Space Business, a Financial Analysis
• Spaceport Activity Impact Study
• Survey of Factors Enhancing the Growth of Aerospace Industry in Florida
• Evaluation of Impact of Space Related Activities in the State of Hawai
Simultaneous light and radial velocity curve solutions for U Cephei
The light-curve synthesis approach of Wilson & Devinney has been used to solve simultaneously light and radial velocity curves of the Algol-type eclipsing binary star U Cephei. We have performed eight new differential corrections solutions using the photometric data of Markworth and the radial velocity data of Batten to obtain a consistent set of orbital and astrophysical parameters for the light and velocity curves of this famous system. We find U Cephei to be best modeled using the semidetached (mode 5) system geometry of the Wilson & Devinney program, with a primary rotating at about 5.2 times its synchronous rate, and have found absolute system parameters to be = 4.93 M0, M2 = 3.27 M0, Ri = 2.77 R0, and R2 = 5.22 RQ
Velocity measurements of humans by computers
Distance and time, two fundamental quantities, are discussed early in most introductory physics courses. By dividing a change in distance by time to get velocity, and by dividing a change in velocity by time to get acceleration, two more important quantities result. With these the real world of automobiles and jet planes and applications of Newton\u27s second law is available for interpretation from an analytical point of view. In order to get students thinking reliably about these important ideas it seems important to have direct measurements of distance and time over short enough intervals to talk sensibly about instantaneous velocities
On the Selection of Photometric Planetary Transits
We present a new method for differentiating between planetary transits and
eclipsing binaries based on the presence of the ellipsoidal light variations.
These variations can be used to detect stellar secondaries with masses ~0.2
M_sun orbiting sun-like stars at a photometric accuracy level which has already
been achieved in transit surveys. By removing candidates exhibiting this effect
it is possible to greatly reduce the number of objects requiring spectroscopic
follow up with large telescopes. Unlike the usual candidate selection method,
which are primarily based on the estimated radius of the orbiting object, this
technique is not biased against bona-fide planets and brown dwarfs with large
radii, because the amplitude of the effect depends on the transiting object's
mass and orbital distance. In many binary systems, where a candidate planetary
transit is actually due to the partial eclipse of two normal stars, the
presence of flux variations due to the gravity darkening effect will show the
true nature of these systems. We show that many of the recent OGLE-III
photometric transit candidates exhibit the presence of significant variations
in their light curves and are likely to be due to stellar secondaries. We find
that the light curves of white dwarf transits will generally not mimic those of
small planets because of significant gravitationally induced flux variations.
We discuss the relative merits of methods used to detect transit candidates
which are due to stellar blends rather than planets. We outline how photometric
observations taken in two bands can be used to detect the presence of stellar
blends.Comment: ApJ, 11 pages, 2 figures, 1 table, replaced with accepted versio
Towards a Continuous Record of the Sky
It is currently feasible to start a continuous digital record of the entire
sky sensitive to any visual magnitude brighter than 15 each night. Such a
record could be created with a modest array of small telescopes, which
collectively generate no more than a few Gigabytes of data daily.
Alternatively, a few small telescopes could continually re-point to scan and
reco rd the entire sky down to any visual magnitude brighter than 15 with a
recurrence epoch of at most a few weeks, again always generating less than one
Gigabyte of data each night. These estimates derive from CCD ability and
budgets typical of university research projects. As a prototype, we have
developed and are utilizing an inexpensive single-telescope system that obtains
optical data from about 1500 square degrees. We discuss the general case of
creating and storing data from a both an epochal survey, where a small number
of telescopes continually scan the sky, and a continuous survey, composed of a
constellation of telescopes dedicated each continually inspect a designated
section of the sky. We compute specific limitations of canonical surveys in
visible light, and estimate that all-sky continuous visual light surveys could
be sensitive to magnitude 20 in a single night by about 2010. Possible
scientific returns of continuous and epochal sky surveys include continued
monitoring of most known variable stars, establishing case histories for
variables of future interest, uncovering new forms of stellar variability,
discovering the brightest cases of microlensing, discovering new novae and
supernovae, discovering new counterparts to gamma-ray bursts, monitoring known
Solar System objects, discovering new Solar System objects, and discovering
objects that might strike the Earth.Comment: 38 pages, 9 postscript figures, 2 gif images. Revised and new section
added. Accepted to PASP. Source code submitted to ASCL.ne
OT 060420: A Seemingly Optical Transient Recorded by All-Sky Cameras
We report on a ~5th magnitude flash detected for approximately 10 minutes by
two CONCAM all-sky cameras located in Cerro Pachon - Chile and La Palma -
Spain. A third all-sky camera, located in Cerro Paranal - Chile did not detect
the flash, and therefore the authors of this paper suggest that the flash was a
series of cosmic-ray hits, meteors, or satellite glints. Another proposed
hypothesis is that the flash was an astronomical transient with variable
luminosity. In this paper we discuss bright optical transient detection using
fish-eye all-sky monitors, analyze the apparently false-positive optical
transient, and propose possible causes to false optical transient detection in
all-sky cameras.Comment: 7 figures, 3 tables, accepted PAS
Eclipsing binaries in open clusters. II. V453 Cyg in NGC 6871
We derive absolute dimensions of the early B-type detached eclipsing binary
V453 Cygni (B0.4 IV + B0.7 IV, P=3.89d), a member of the open cluster NGC 6871.
From the analysis of new, high-resolution, spectroscopy and the UBV light
curves of Cohen (1974) we find the masses to be 14.36 +/- 0.20 and 11.11 +/-
0.13 Msun, the radii to be 8.55 +/- 0.06 and 5.49 +/- 0.06 Rsun, and the
effective temperatures to be 26600 +/- 500 and 25 500 +/- 800 K for the primary
and secondary stars, respectively. The surface gravities of 3.731 +/- 0.012 and
4.005 +/- 0.015 indicate that V453 Cyg is reaching the end of its main sequence
lifetime. We have determined the apsidal motion period of the system to be 66.4
+/- 1.8 yr using the technique of Lacy (1992) extended to include spectroscopic
data as well as times of minimum light, giving a density concentration
coefficient of log(k_2) = -2.226 +/- 0.024. Contaminating (third) light has
been detected for the first time in the light curve of V453 Cyg; previous
analyses without this effect systematically underestimate the ratio of the
radii of the two stars. The absolute dimensions of the system have been
compared to the stellar evolution models of the Granada, Geneva, Padova and
Cambridge groups. All model sets fit the data on V453 Cyg for solar helium and
metal abundances and an age of 10.0 +/- 0.2 Myr. The Granada models also agree
fully with the observed log(k_2) once general relativistic effects have been
accounted for. The Cambridge models with convective core overshooting fit V453
Cyg better than those without. Given this success of the theoretical
predictions, we briefly discuss which eclipsing binaries should be studied in
order to further challenge the models.Comment: Accepted for publication in MNRAS (14 pages, 5 figures, Fig.4 reduced
in size
The PLATO 2.0 mission
PLATO 2.0 has recently been selected for ESA's M3 launch opportunity (2022/24). Providing accurate key planet parameters (radius, mass, density and age) in statistical numbers, it addresses fundamental questions such as: How do planetary systems form and evolve? Are there other systems with planets like ours, including potentially habitable planets? The PLATO 2.0 instrument consists of 34 small aperture telescopes (32 with 25 s readout cadence and 2 with 2.5 s candence) providing a wide field-of-view (2232 deg 2) and a large photometric magnitude range (4-16 mag). It focusses on bright (4-11 mag) stars in wide fields to detect and characterize planets down to Earth-size by photometric transits, whose masses can then be determined by ground-based radial-velocity follow-up measurements. Asteroseismology will be performed for these bright stars to obtain highly accurate stellar parameters, including masses and ages. The combination of bright targets and asteroseismology results in high accuracy for the bulk planet parameters: 2 %, 4-10 % and 10 % for planet radii, masses and ages, respectively. The planned baseline observing strategy includes two long pointings (2-3 years) to detect and bulk characterize planets reaching into the habitable zone (HZ) of solar-like stars and an additional step-and-stare phase to cover in total about 50 % of the sky. PLATO 2.0 will observe up to 1,000,000 stars and detect and characterize hundreds of small planets, and thousands of planets in the Neptune to gas giant regime out to the HZ. It will therefore provide the first large-scale catalogue of bulk characterized planets with accurate radii, masses, mean densities and ages. This catalogue will include terrestrial planets at intermediate orbital distances, where surface temperatures are moderate. Coverage of this parameter range with statistical numbers of bulk characterized planets is unique to PLATO 2.0. The PLATO 2.0 catalogue allows us to e.g.: - complete our knowledge of planet diversity for low-mass objects, - correlate the planet mean density-orbital distance distribution with predictions from planet formation theories,- constrain the influence of planet migration and scattering on the architecture of multiple systems, and - specify how planet and system parameters change with host star characteristics, such as type, metallicity and age. The catalogue will allow us to study planets and planetary systems at different evolutionary phases. It will further provide a census for small, low-mass planets. This will serve to identify objects which retained their primordial hydrogen atmosphere and in general the typical characteristics of planets in such low-mass, low-density range. Planets detected by PLATO 2.0 will orbit bright stars and many of them will be targets for future atmosphere spectroscopy exploring their atmosphere. Furthermore, the mission has the potential to detect exomoons, planetary rings, binary and Trojan planets. The planetary science possible with PLATO 2.0 is complemented by its impact on stellar and galactic science via asteroseismology as well as light curves of all kinds of variable stars, together with observations of stellar clusters of different ages. This will allow us to improve stellar models and study stellar activity. A large number of well-known ages from red giant stars will probe the structure and evolution of our Galaxy. Asteroseismic ages of bright stars for different phases of stellar evolution allow calibrating stellar age-rotation relationships. Together with the results of ESA's Gaia mission, the results of PLATO 2.0 will provide a huge legacy to planetary, stellar and galactic science
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