Graduate Student Savanah Turner Publishes Study of over 300 L and T dwarfs

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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A photometric-study of BL Herculis
Aaron L. Alexander, Michael D. Joner, and D. Harold McNamara

Photometric (uvby β) observations ofthe prototype variable BL Her are described. The photometry indicates the variable is reddened. We have adopted E(b — y) = 0ṃ055. Intrinsic (b—y) and c₁ values are used to derive the mean temperature and surface gravity ‹T eff› = 6660 K, and ‹log g› = 2.46. The (m₁ =0.198 indicating the variable is very metal strong. We infer that [Fe/H] = + 0.20. An application of a modified Baade-Wesselink analysis to the photometric and radial-velocity data in the phase interval 0.45 ≤ φ ≤ 0.775, when most ofthe light variation can be attributed to a change in radius, yields (R) = 8.5 R⊙ and ‹Mv› = -0.5. The radius and surface gravity indicate that the mass is 𝕸 ≃ 0.75 𝕸⊙

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The relative merits of 7 photometric temperature indexes for disk-population k-giants
Benjamin J. Taylor, Scott B. Johnson, and Michael D. Joner
The authors report accidental errors and blanketing sensitivities for seven disk K giant temperature indices: Johnson J-K, Cousins R-I, Johnson R-I, Kron R-I, the Spinrad-Taylor T index. T1-T2, and V-K. The authors ultimately compare these indices to a blanketing-free color index, with the latter being derived from narrowband photometry, empirical blocking data, and a model-atmosphere backwarming correction. They also investigate the anomalous R band blanketing reported by Frogel, Whitford, and Rich for Baade's Window K giants.
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Ddo, cousins r-i, and photomultiplier scanner data for an analysis of very strong lined k-giants
Scott B. Johnson, Michael D. Joner, and Benjamin J. Taylor
The authors present new data which will contribute to an analysis of the so-called super-metal-rich K giants. The results include DDO photometry and photomultiplier scanner data; some of the latter reflect blanketing and feature strengths, and the rest bear primarily on stellar temperatures. Some of the scanner data are transformed to the Cousins R-I system and are given with previously published measurements on this system.
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The nature of the dwarf cepheid EH Librae

Photometry (uvby β) of EH Lib has been secured and analyzed. A small correction is made to the period in order to better predict times of light maxima. A reddening value, E(b — y) = +0ṃ041, is derived from standard calibrations applied to the photometry. Intrinsic (b—y) and c₁ values are used to determine a mean effective temperature, ‹Teff› = 7840 K, and a mean surface gravity, ‹log g› = 4.08. The metal abundance, [Fe/H] = -0.015, is determined from δm₁ Using new and previously published spectroscopie data, a mean radius, ‹R› = 2.4 R⊙, is derived using a Wesselink method. The radius and effective temperature indicate a mean absolute bolometric magnitude, ‹Mbol› = + 1.5. Also a m

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Revised photometric properties for the multiperiodic variable HD-200925
Scott B. Johnson and Michael D. Joner

Over 700 observations of HD 200925 in the uvby and ß systems have been secured and analyzed. Our data show that this variable is multiperiodic. A reddening value, E(b-y) = 0ṃ029, has been derived from the observations. The reddening-corrected normals for y, (b-y), and c₁ yield a mean effective temperature, ‹Teff›=7020 K, a mean surface gravity, ‹log g›=3.44, and a mean bolometric magnitude, ‹Mbol› = 0ṃ8. We determine a preliminary mean radius, ‹R› = 4.1 R⊙. Our m₁ data show that the blanketing is high, but this index varies in an anomalous way which precludes a definitive determination of [Fe/H]. We consider two possible explanations for the behavior of the m₁ index. One is high microturbulance excited by the secondary pulsation mode, the other is the Am/Fm phenomenon. We find that the parameters from the Imbert (1980) radial velocity curve are essentially unchanged by our analysis. The Baade-Wesselink method fails for this star.

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Cousins vri photometry of the hyades, coma, and m67
For little-evolved stars in the Hyades, Coma, and M67, Cousins VRI photometry which includes and expands on results published in other systems by Taylor is presented. Observing and reduction procedures and error analysis are discussed in some detail, and evidence is presented that the transformations to the Cousins system are satisfactory and the results are internally consistent. Comparisons with data published by Mendoza yield agreement in R-I and V-R for the Hyades and V-R for M67. Disagreement is found, however, in both color indices for Coma and in R-I for M67, and reasons are suggested for favoring the obtained results in these cases. By comparing Mendoza's M67 K-giant data with those of other observers, it is found that any problem with Mendoza's M67 results is apparently limited to the faintest stars he observed. A suggestion by Schild and Weeks that Mendoza's M67 R magnitudes are about 0.1 mag in error is also tested, and it is found that available evidence does not support this suggestion.