Utah Aurora - May 10/11 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

Thumbnail of figure from publication
Multiwavelength monitoring of the BL Lacertae object PKS 2155-304 in 1994 May .1. The ground-based campaign
M. D. Joner (et al.)
Optical, near-infrared, and radio observations of the BL Lac object PKS 2155-304 were obtained simultaneously with a continuous UV/EUV/X-ray monitoring campaign in 1994 May. Further optical observations were gathered throughout most of 1994. The radio, millimeter, and near-infrared data show no strong correlations with the higher energies. The optical light curves exhibit flickering of 0.2-0.3 mag on timescales of 1-2 days, superposed on longer timescale variations. sapid variations of similar to 0.01 mag minute(-1), if real, are the fastest seen to date for any BL Lac object. Small (0.2-0.3 mag) increases in the V and R bands occur simultaneously with a flare seen at higher energies. All optical wave bands (UBVRI) track each other well over the period of observation, with no detectable delay. For most of the period the average colors remain relatively constant, although there is a tendency for the colors (in particular, B-V) to vary more when the source fades. In polarized light, PKS 2155-304 showed strong color dependence (polarization increases toward the blue, P-U/P-I = 1.31) and the highest optical polarization (U = 14.3%) ever observed for this source. The polarization variations trace the flares seen in the UV flux. For the fastest variability timescale observed, we estimate a central black hole mass of less than or similar to 1.5 x 10(9)(delta/10) M-., consistent with UV and X-ray constraints and smaller than previously calculated for this object.
Thumbnail of figure from publication
A photometric study of V798 Cygni
Chulhee Kim and Michael D. Joner

New photometric (uvby beta) observations of the intrinsic variable star V798 Cyg have been secured and used to derive values of foreground reddening, E(b-y) = 0.117 mag, and metallicity, [Fe/H] = 0.64. Intrinsic (b-y) and c(1) values indicate a mean effective temperature, [T-eff] = 7150 K, and a mean surface gravity, [log g] = 3.39. Pulsation theory and theoretical evolutionary tracks yield a mass of 2.3 M. and an age of 0.63 Gyr. Although V798 Cyg has been described as being multiperiodic, this conclusion is not confirmed by our observations. V798 Cyg in most respects resembles a typical Population I dwarf Cepheid.

Thumbnail of figure from publication
Fourier decomposition of the light curves of three dwarf Cepheids: CY Aquarii, XX Cygni, and V798 Cygni

The three dwarf Cepheid variable stars CY Aquarii, XX Cygni, and V798 Cygni were examined with CCD time series ensemble photometry. The Fourier decomposition of the light curves showed no evidence that any of the three stars was a double-mode variable. CY Aqr was fit with a nine-term harmonic series with a residual error of 10 mmag. XX Cyg was fit with a ten-term harmonic series with a residual error of 10 mmag. V798 Cyg was fit with a four-term harmonic series with a residual error of 7 mmag. In addition, we examined a set of double-mode dwarf Cepheids with the same Fourier decomposition techniques. We present evidence that these double-mode dwarf Cepheids fill the gap in the amplitude-ratio distribution reported by Antonello et al. (1986, A&A, 169, 122) and Poretti et al. (1990, A&A, 228, 350).

Thumbnail of figure from publication
The bipolar structure of the LBV nebula around HR Carinae
M. D. Joner (et al.)
HR Carinae is one of the few Luminous Blue Variables (LBVs) in the Galaxy. It has a nebula that appears bipolar. We have obtained imaging and high-dispersion, long-slit echelle data of the HR Car nebula, and confirmed that it is a bipolar nebula. Its polar axis lies along the position angle of 125 +/- 5 degrees; each lobe has. at a distance of 5 kpc a diameter of similar to 0.65 pc and a line-of-sight expansion velocity of 75 - 150 km s(-1). Beside the expanding bipolar lobes, a number of [N II]-bright knots are detected. These knots have lower expansion velocities than the lobes and are detected only within the projected boundary of the lobes. These knots are most likely nitrogen-enriched material ejected by HR Car, On a larger scale, a funnel-shaped nebula is detected at 2.'5 northwest of HR Car. The axis of the funnel is roughly aligned with the polar axis of the HR Car nebula, suggesting that HR Car may be responsible for the ionization and shaping of this nebula. Future observations of kinematics and abundances are needed to determine the nature of this nebula. We propose that the bipolar nebula of HR Car is a more evolved version of the Homunculus Nebula around eta Car. The recently developed theory of wind-compressed disks may explain the higher density of the equatorial plane and the formation of bipolar nebulae of LBVs.
Thumbnail of figure from publication
Time-series ensemble photometry of SX phoenicis stars .1. BL Camelopardalis
Eric G. Hintz, Michael D. Joner, D. Harold McNamara, Kenneth A. Nelson, J. Ward Moody, and Chulhee Kim

We present an analysis of the multiperiodic SX Phoenicis star BL Camelopardalis (GD 428). Along with 24 times of maximum light from archival data, six previously unpublished times of maximum light from photomultiplier observations and 39 new CCD observations of maximum light are reported. The new CCD observations indicate that BL Cam is a double-mode variable with a primary period of 0.0391 day, a secondary period of 0.0306 day, and a pi(1)/pi(0) ratio of 0.783. The relation between metallicity and period ratio for large-amplitude delta Scuti variables is examined in detail. Finally, evidence is presented that the fundamental period pi(0) has increased by 0.009 s in the last 20 years.

Thumbnail of figure from publication
The physical properties of the SX Phoenicis star CY Aquarii
D. H. McNamara, John M. Powell, and Michael D. Joner

Photometry of CY Aqr in the uvby beta and V(RI)(C) photometric systems has been secured and analyzed. A phase-averaged effective gravity of log g(eff)=4.04 and effective temperature of 7740 K are found from model-atmosphere grids. The star is metal poor with a derived [Fe/H]=-1.5. A mass of 1.06 M(.) is found from the analysis, the radius is 1.59 R(.), and absolute visual magnitude is M(V)=2.5.