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
Stromgren uvby beta photometry of SX Phoenicis and large-amplitude delta Scuti variables is analyzed to determine the mean temperatures, metal abundances, and surface gravities of the stars. The mean temperatures and fundamental periods are used in conjunction with the pulsation equation and stellar models to derive masses, radii, surface gravities, and M-bol Of the variables. The stars exhibit a period-luminosity relation. With the aid of HIPPARCOS trigonometric parallaxes the zero point of the M-v, P relation is set. We find (Eq. 1) M-v= -3.725 log P-1.933. This P-L relation is utilized to find the M-v values of RR Lyrae stars or horizontal-branch stars in globular clusters and the Carina galaxy objects that contain both SX Phe, and RR Lyrae variables, or horizontal-branch stars. The M-v values of the metal-poor RR Lyrae stars are found to be consistent with M-v, [Fe/H] calibrations derived by Sandage (AJ, 106, 703, 1993) and by McNamara (PASP, 109, 857, 1997). The latter is based on revised Baade-Wesselink M-v values. At [Fe/H]= -1.9 M-v is 0.42. Feast and Catchpole's (MNRAS, 286, L1, 1997) suggestion that M-v = 0.25 at [Fe/H] = -1.9 for RR Lyrae is discussed. This M-v value is too luminous because it makes the (T-eff) of RR Lyraes too high-well off any T-eff= f (color index) calibration. The distance to the Large Magellanic Cloud is discussed. The ''best'' distance modulus based on recent determinations is 18.57 +/- 0.03.
We present a new calibration of the relationship between the absolute magnitudes and metal abundances, [Fe/H], of RR Lyrae stars. Temperatures inferred from optical and near-infrared color indices and the new Kurucz models are utilized in conjunction with Baade-Wesselink solutions to derive absolute magnitudes. Temperatures inferred from the optical and near-infrared photometry are similar to 200-300 K higher for the variables than those given from (V-K) color indices and the older Kurucz models. We find M-v = 0.28[CFe/H] + 0.964. This equation gives higher luminosities (similar to 0.2 mag) for the metal-poor variables than previous B-W calibrations. The RR Lyrae stars in the Large Magellanic Cloud in conjunction with our calibration yield a distance modulus of 18.53. Thus, the Cepheids and RR Lyrae stars give identical distance moduli at less than or equal to 0.1 mag level. The repercussions of the higher temperatures and higher luminosities of RR Lyrae stars on the distances and ages of globular clusters, distance to the galactic center, the Hubble constant and age of the Universe, and the masses of RR Lyrae stars are discussed.