Giant Sunspots - August 12, 2024

BYU Astronomy Research Group Joins the Astrophysical Research Consortium (ARC)

As of January 2021 BYU will be a member of the ARC Consortium (Link to Consortium) with access to the ARC 3.5-m telescope and the 0.5-m ARCSAT telescope.  The primary use of the ARC 3.5-m telescope time is for graduate student projects.  This provides a wide array of instrumentation that is currently being used to study objects in the solar system all the way to studies of the large scale structure of the Universe.

Other BYU Astronomy Facilities

In addition to our telescope time from the ARC consortium, we operate a number of our own astronomical facilities

West Mountain Observatory (West Mountain)

This is our mountain observatory at about 6600 ft above sea level.  This consists of three telescopes: 0.9-m, 0.5-m, and a 0.32-m. It is a 40 minute drive that ends in a 5 miles drive up a dirt road. The mountain itself can be seen from campus. We don't provide any tours of this facility.

Orson Pratt Observatory

The Orson Pratt Observatory is named for an early apostle of the Church of Jesus Christ of Latter-Day Saints.  It is our campus telescope facility and contains a wide variety of telescopes for student research and public outreach. We operate a 24" PlaneWave telescope in the main campus dome, plus a 16", two 12", one 8", and a 6" telescope on our observation deck.  The telescopes are all fully robotic. Beyond this we have a large sections of telescopes used on public nights.

Royden G. Derrick Planetarium (Planetarium)

This is a 119 seat, 39" dome planetarium with acoustically treated walls to allow it's use as a lecture room. Recently we upgraded to an E&S Digistar7 operating system with 4K projectors.  The planetarium is used for teaching classes, public outreach, and astronomy education research projects.





Selected Publications

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The metallicity of mu Leonis
Abstract: Castro et al. (1996) have concluded that mu Leo has three times the solar metallicity. That conclusion is based on their own work and on rezeroed values of [Fe/H] from the literature. A review of their paper reveals that there are significant omissions from their list of literature results. In addition, their procedure for establishing zero points for values of [Fe/H] is found to be fallacious. If that zero-point procedure is nonetheless accepted at face value, and if Hyades data available at the time are used, the zero-point procedure yields metallicities for the Hyades giants that appear to differ from those for Hyades dwarfs. The difference is in the opposite sense to that found by Griffin & Holweger (1989). As a first step in resolving these problems, the zero-point procedure is discussed in some detail. Next, the Hyades problem is reconsidered by taking all published data into account. In agreement with a conclusion drawn by Taylor (1998b), no evidence is found for a metallicity difference between Hyades giants and Hyades dwarfs. Published values of [Fe/H] for mu Leo are then analyzed. The technique applied to those data avoids the zero-point problem described above. In addition, it permits the scatter in the mu Leo data to be compared to the scatter in data from about 1000 other stars. In agreement with Taylor (1996), it is found that the value of [Fe/H] for mu Leo does not conclusively exceed +0.2 dex. In addition, it is found that the scatter in the mu Leo data is consistent with data scatter for other stars. In contrast, the scatter in the data considered by Castro et al. is found to be unrealistically small. A number of pertinent issues raised by this review are highlighted to encourage future discussion.
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A zero point and accidental errors for published values of [Fe/H] for cool giants
Abstract: This paper is one of a series based on published values of [Fe/H] for late-type evolved stars. Only values of [Fe/H] from high-dispersion spectroscopy or related techniques are used. The narrative in this paper begins at a point where mean values of [Fe/H] have been derived for epsilon Vir, alpha Boo, beta Gem, and the Hyades giants. By using these stars as standard stars when necessary, a zero-point data base is assembled. This data base is then expanded into its final version by correcting and adding additional data in a step-by-step process. As that process proceeds, data comparisons are used to establish rms errors. Derived rms errors per datum are found to be about 0.10 - 0.12 dex, and they appear to be too large to be explained by line-to-line scatter and temperature effects.
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Catalogs of temperatures and [Fe/H] averages for evolved G and K stars
Abstract: A catalog of mean values of [Fe/H] for evolved G and K stars is described. The zero point for the catalog entries has been established by using differential analyses. Literature sources for those entries are included in the catalog. The mean values are given with rms errors and numbers of degrees of freedom, and a simple example of the use of these statistical data is given. For a number of the stars with entries in the catalog, temperatures have been determined. A separate catalog containing those data is briefly described.
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Analyses of archival [Fe/H] results for cool evolved stars. I. Basic rules and [Fe/H] corrections
Abstract: This paper is the first in a series based on published values of [Fe/H] for late-type evolved stars. Only results from high-dispersion spectroscopy or related techniques are used. From these data, an "analysis catalog" is to be produced containing mean values of [Fe/H] and accidental errors. Such a catalog was published by Taylor in 1991 and is now to be updated. Basic protocols for selecting and analyzing input values of [Fe/H] are stated here. A procedure is described for calculating preferred temperatures and adjusting input values of [Fe/H] to correspond to those temperatures. Ten other possible [Fe/H] corrections are also mentioned, with three corrections that can be applied being described in some detail. These are (1) corrections for use of nonuniform grids of model atmospheres, (2) corrections for use of solar equivalent widths that are not on the Liege system, and (3) corrections for non-LTE effects.
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Analyses of archival [Fe/H] results for cool evolved stairs. II. [Fe/H] standard stars
Abstract: This paper is the second in a series based on published values of [Fe/H] for late-type evolved stars. Only high-dispersion results are considered here. Such data are used to derive mean values of [Fe/H] for stars that have often been used as [Fe/H] standard stars. For epsilon Vir and beta Gem, the mean values of [Fe/H] obtained here are +0.04 +/- 0.04 dex and 0.00 +/- 0.03 dex, respectively. For alpha Boo, [Fe/H] is found to be -0.55 +/- 0.02 dex. For the Hyades, a mean value of [Fe/H] obtained for giants can be combined with a counterpart published previously for dwarfs. The result is +0.10 +/-. 0.01 dex. Using available evidence, 0.049 dex is the smallest [Fe/H] difference that can be detected between Hyades giants and Hyades dwarfs. No such difference is found.
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Multicolor, two-dimensional photometric study of galaxies in rich Abell clusters .1. Observations and reductions
Abstract: We have embarked on a long term project to obtain high precision photometry on individual galaxies in 45 rich clusters of galaxies. Data from the first set of six clusters have yielded BVRI photometric information on 961 galaxies and 384 stars. These objects come from the central one Mpc of Abell 576, 957, 1185, 1377, 2063, and 2657, each of which is of richness class R greater than or equal to 1. Each object was examined with two radial surface brightness fitting functions, and an asymptotic magnitude was determined. One fitting function produced a shape parameter beta which, when taken in. combination with the color index (B-I), shows a breakdown of the three basic morphological types (E, S0, and S) into four beta types and a set of peculiar galaxies. Our results match previous studies well, and also provide some new insights into the clusters. In addition, we have examined the effects of plate scale on the determination of these photometric parameters. All parameters were found to repeat across plate scale differences. We also examined the effects of co-adding frames in an attempt to understand the degradation or improvement of the photometric parameters with increasing signal-to-noise. (C) 1997 American Astronomical Society.