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 catalog of temperatures and red Cousins photometry for the Hyades
Using Hyades photometry published by Mendoza and other authors, Pinsonneault et al. have recently concluded that Cousins V - I photometry published by Taylor & Joner is not on the Cousins system. Extensive tests of the Taylor- Joner photometry and other pertinent results are therefore performed in this paper. It is found that in part, the Pinsonneault et al. conclusion rests on ( 1) a systematic error in Mendoza's ( R - I)(J) photometry and ( 2) a small error in an approximate Johnson- to- Cousins transformation published by Bessell. For the Taylor- Joner values of ( V - R)(C), it is found that there are possible ( though not definite) differences of several mmag with other results. However, the Taylor- Joner values of ( R - I)(C) data are supported at the 1 mmag level. Using the ( R - I)(C) data and other published results, an ( R - I)(C) catalog is assembled for 146 Hyades stars with spectral types earlier than about K5. For single stars with multiple contributing data, the rms errors of the catalog entries are less than 4.4 mmag. Temperatures on the Di Benedetto angular- diameter scale are also given in the catalog and are used to help update published analyses of high- dispersion values of [ Fe/ H] for the Hyades. The best current mean Hyades value of [ Fe/ H] is found to be + 0.103 +/- 0.008 dex and is essentially unchanged from its previous value. In addition to these numerical results, recommendations are made about improving attitudes and practices that are pertinent to issues like those raised by Pinsonneault et al.
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Physical Science Foundations, 1st Edition
J. Ward Moody, M. Jeannette Lawler, Juliana Boerio-Goates, R. Steven Turley, David V. Dearden, Bart J. Kowallis, and Michael D. Joner
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Period changes in the SX Phoenicis Star DY Pegasi
Eric G. Hintz, Michael D. Joner, and Mariya Ivanushkina (et al.)
We report 69 new times of maximum light for the SX Phoenicis star DY Pegasi. Combining these new times with previous published maxima, we found the data to be well modeled with a triple linear fit. However, we also determined a refined constant period change of -6.00x10(-12) days day(-1). From both spectroscopic and photometric measurements, we determined -0.8<[Fe/H]<-0.6. Using phase-averaged indices, we found =7660 and =3.89. From evolutionary models, a mass of M=1.5 M-circle dot and an age of 1.7 Gyr were determined.
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Pulsational behaviour of the HADS RY Lep
C. D. Laney and M. Joner (et al.)
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HADS, multiple periods, period changes and the PL Relation
C. D. Laney and Michael D. Joner (et al.)
High-Amplitude Delta Scuti stars (dwarf Cepheids) typically have one or two radial modes with stable amplitudes, but there are few real `clockwork stars'. Periods can change abruptly, and apparently smooth trends in period changes can alter or reverse abruptly. Interaction terms complicate analysis in double-mode stars, and two stars in our sample turned out to have previously unknown binary companions. AI Vel and RY Lep appear to have low-level nonradial modes present as well as the dominant radial mode(s). In RY Lep, it appears that the amplitude of the possible nonradial mode may vary considerably with time. Data for the three double-mode dwarf Cepheids studied so far do not support the idea that the fundamental mode is necessarily more sinusoidal than the first overtone. This suggests that caution is advisable in using skewness to decide whether a monoperiodic HADS is a fundamental pulsator. Nonetheless, reliable BW radii and luminosities can be derived for most dwarf Cepheids, and the resulting PR (and hence PL) relation appears to be an extension of the PR (and PL) relations for classical Cepheids.
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RY Lep: a dwarf Cepheid hits a midlife crisis
C. D. Laney, Michael D. Joner, and L. Schwendiman
RY Lep is a dwarf Cepheid (HADS) with a period of about 0.2251d. Published optical photometry and JK photometry from 1985-97 appeared to show stable monoperiodic behaviour, but radial velocities and infra-red photometry from 2000 January -February show aperiodic (or possibly multiperiodic) variations not consistent with previous observations. An apparently similar anomalous interval can be seen in the hipparcos epoch photometry. RY Lep appears to have a normal temperature, radius and luminosity for a HADS with a period of 0.225d, occasional bursts of weirdness notwithstanding. Although the radial velocities clearly show binary motion, the period is more than 500d, making binary interaction unlikely.