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

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A giant planet undergoing extreme-ultraviolet irradiation by its hot massive-star host
Mary T. Dumont, Clement Gaillard, Kyle Matt, Denice C. Stephens, and Michael D. Joner (et al.)
The amount of ultraviolet irradiation and ablation experienced by a planet depends strongly on the temperature of its host star. Of the thousands of extrasolar planets now known, only six have been found that transit hot, A-type stars (with temperatures of 7,300–10,000 kelvin), and no planets are known to transit the even hotter B-type stars. For example, WASP-33 is an A-type star with a temperature of about 7,430 kelvin, which hosts the hottest known transiting planet, WASP-33b (ref. 1); the planet is itself as hot as a red dwarf star of type M (ref. 2). WASP-33b displays a large heat differential between its dayside and nightside2, and is highly inflated–traits that have been linked to high insolation3, 4. However, even at the temperature of its dayside, its atmosphere probably resembles the molecule-dominated atmospheres of other planets and, given the level of ultraviolet irradiation it experiences, its atmosphere is unlikely to be substantially ablated over the lifetime of its star. Here we report observations of the bright star HD 195689 (also known as KELT-9), which reveal a close-in (orbital period of about 1.48 days) transiting giant planet, KELT-9b. At approximately 10,170 kelvin, the host star is at the dividing line between stars of type A and B, and we measure the dayside temperature of KELT-9b to be about 4,600 kelvin. This is as hot as stars of stellar type K4 (ref. 5). The molecules in K stars are entirely dissociated, and so the primary sources of opacity in the dayside atmosphere of KELT-9b are probably atomic metals. Furthermore, KELT-9b receives 700 times more extreme-ultraviolet radiation (that is, with wavelengths shorter than 91.2 nanometres) than WASP-33b, leading to a predicted range of mass-loss rates that could leave the planet largely stripped of its envelope during the main-sequence lifetime of the host star.
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KELT-18b: Puffy Planet, Hot Host, Probably Perturbed

We report the discovery of KELT-18b, a transiting hot Jupiter in a 2.87-day orbit around the bright (V = 10.1), hot, F4V star BD+60 1538 (TYC 3865-1173-1). We present follow-up photometry, spectroscopy, and adaptive optics imaging that allow a detailed characterization of the system. Our preferred model fits yield a host stellar temperature of K and a mass of , situating it as one of only a handful of known transiting planets with hosts that are as hot, massive, and bright. The planet has a mass of , a radius of , and a density of , making it one of the most inflated planets known around a hot star. We argue that KELT-18b’s high temperature and low surface gravity, which yield an estimated ∼600 km atmospheric scale height, combined with its hot, bright host, make it an excellent candidate for observations aimed at atmospheric characterization. We also present evidence for a bound stellar companion at a projected separation of ∼1100 au, and speculate that it may have contributed to the strong misalignment we suspect between KELT-18's spin axis and its planet’s orbital axis. The inferior conjunction time is 2457542.524998 ± 0.000416 (BJDTDB) and the orbital period is 2.8717510 ± 0.0000029 days. We encourage Rossiter–McLaughlin measurements in the near future to confirm the suspected spin–orbit misalignment of this system.

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Reverberation Mapping of Optical Emission Lines in Five Active Galaxies
M. D. Joner and M. Spencer (et al.)
We present the first results from an optical reverberation mapping campaign executed in 2014 targeting the active galactic nuclei (AGNs) MCG+08-11-011, NGC 2617, NGC 4051, 3C 382, and Mrk 374. Our targets have diverse and interesting observational properties, including a “changing look” AGN and a broad-line radio galaxy. Based on continuum-H β lags, we measure black hole masses for all five targets. We also obtain H γ and He ii λ 4686 lags for all objects except 3C 382. The He ii λ 4686 lags indicate radial stratification of the BLR, and the masses derived from different emission lines are in general agreement. The relative responsivities of these lines are also in qualitative agreement with photoionization models. These spectra have extremely high signal-to-noise ratios (100–300 per pixel) and there are excellent prospects for obtaining velocity-resolved reverberation signatures.
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Swift Monitoring of NGC 4151: Evidence for a Second X-Ray/UV Reprocessing
M. Joner (et al.)
Swift monitoring of NGC 4151 with an ∼6 hr sampling over a total of 69 days in early 2016 is used to construct light curves covering five bands in the X-rays (0.3–50 keV) and six in the ultraviolet (UV)/optical (1900–5500 Å). The three hardest X-ray bands (>2.5 keV) are all strongly correlated with no measurable interband lag, while the two softer bands show lower variability and weaker correlations. The UV/optical bands are significantly correlated with the X-rays, lagging ∼3–4 days behind the hard X-rays. The variability within the UV/optical bands is also strongly correlated, with the UV appearing to lead the optical by ∼0.5–1 days. This combination of ≳3 day lags between the X-rays and UV and ≲1 day lags within the UV/optical appears to rule out the “lamp-post” reprocessing model in which a hot, X-ray emitting corona directly illuminates the accretion disk, which then reprocesses the energy in the UV/optical. Instead, these results appear consistent with the Gardner & Done picture in which two separate reprocessings occur: first, emission from the corona illuminates an extreme-UV-emitting toroidal component that shields the disk from the corona; this then heats the extreme-UV component, which illuminates the disk and drives its variability.
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KELT-11b: A Highly Inflated Sub-Saturn Exoplanet Transiting the V = 8 Subgiant HD 93396

We report the discovery of a transiting exoplanet, KELT-11b, orbiting the bright (V = 8.0) subgiant HD 93396. A global analysis of the system shows that the host star is an evolved subgiant star with K, , , , and . The planet is a low-mass gas giant in a P = 4.736529 ± 0.00006 day orbit, with MP = 0.195 ± 0.018 , , g cm−3, surface gravity , and equilibrium temperature K. KELT-11 is the brightest known transiting exoplanet host in the southern hemisphere by more than a magnitude and is the sixth brightest transit host to date. The planet is one of the most inflated planets known, with an exceptionally large atmospheric scale height (2763 km), and an associated size of the expected atmospheric transmission signal of 5.6%. These attributes make the KELT-11 system a valuable target for follow-up and atmospheric characterization, and it promises to become one of the benchmark systems for the study of inflated exoplanets.

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KELT-12b: A P ∼ 5 day, Highly Inflated Hot Jupiter Transiting a Mildly Evolved Hot Star
We announce the discovery of KELT-12b, a highly inflated Jupiter-mass planet transiting the mildly evolved, V = 10.64 host star TYC 2619-1057-1. We followed up the initial transit signal in the KELT-North survey data with precise ground-based photometry, high-resolution spectroscopy, precise radial velocity measurements, and high-resolution adaptive optics imaging. Our preferred best-fit model indicates that the host star has $T_\mathrm{eff} = 6279 ± 51$ K,  $\mathrm{log}{g}_\star = 3.89 ± 0.05$, [Fe/H]$ = 0.19_{-0.09}^{+0.08}$,  $M_* =  1.59_{-0.09}^{+0.07} \, M_\odot$, and $R_* = 2.37 ± 0.17 R_\odot$. The planetary companion has $M_\rm{P} = 0.95 ± 0.14 \, M_\rm{J}$, $R_\rm{P} = 1.78_{-0.16}^{+0.17} \, R_\rm{J}$, $\mathrm{log}{g}_\rm{P} = 2.87_{-0.10}^{+0.09}$, and density $\rho_\rm{P} = 0.21_{-0.05}^{+0.07}$ g cm$^{−3}$, making it one of the most inflated giant planets known. Furthermore, for future follow-up, we report a high-precision time of inferior conjunction in $\mathrm{BJD}_\mathrm{TDB}$ of 2,457,083.660459 ± 0.000894 and period of  $P=5.0316216 ± 0.000032$ days. Despite the relatively large separation of ∼0.07 au implied by its ∼5.03-day orbital period, KELT-12b receives significant flux of  ${2.38}_{-0.29}^{+0.32}\times {10}^{9}$ erg s$^{−1}$ cm$^{−2}$ from its host. We compare the radii and insolations of transiting gas giant planets around hot ($T_\mathrm{eff} \geqslant 6250$ K) and cool stars, noting that the observed paucity of known transiting giants around hot stars with low insolation is likely due to selection effects. We underscore the significance of long-term ground-based monitoring of hot stars and space-based targeting of hot stars with the Transiting Exoplanet Survey Satellite to search for inflated gas giants in longer-period orbits.