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Where does space begin? For purposes of spaceflight some would say at the Karman line, currently defined as an altitude of 100 kilometers (60 miles). Others might place a line 80 kilometers (50 miles) above Earth's mean sea level. But there is no sharp physical boundary that marks the end of atmosphere and the beginning of space. In fact, the Karman line itself is near the transition between the upper mesophere and lower thermosphere. Night shining or noctilucent clouds are high-latitude summer apparitions formed at altitudes near the top of the mesophere, up to 80 kilometers or so, also known as polar mesopheric clouds. Auroral bands of the northern (and southern) lights caused by energetic particles exciting atoms in the thermosphere can extend above 80 kilometers to over 600 kilometers altitude. Taken from a cockpit while flying at an altitude of 10 kilometers (33,000 feet) in the realm of stratospheric aeronautics, this snapshot captures both noctilucent clouds and aurora borealis under a starry sky, looking toward planet Earth's horizon and the edge of space.
Check current conditions and historical weather data at the ESC.
Physics professor Ben Frandsen recently received an Early Career Award from the United States Department of Energy
Transtrum received a BYU Early Career Scholarship Award.
Eric Hirschman received an Outstanding Service Award from the College of Physical and Mathematical Sciences.

Selected Publications

BYU Authors: Manuel Berrondo, published in J. Math. Phys.

We present an interpretation of the functions appearing in the Wei–Norman factorization of the evolution operator for a Hamiltonian belonging to the SU(1,1) algebra in terms of the classical solutions of the Generalized Caldirola–Kanai (GCK) oscillator (with time-dependent mass and frequency). Choosing P2, X2, and the dilation operator as a basis for the Lie algebra, we obtain that, out of the six possible orderings for the Wei–Norman factorization of the evolution operator for the GCK Hamiltonian, three of them can be expressed in terms of its classical solutions and the other three involve the classical solutions associated with a mirror Hamiltonian obtained by inverting the mass. In addition, we generalize the Wei–Norman procedure to compute the factorization of other operators, such as a generalized Fresnel transform and the Arnold transform (and its generalizations), obtaining also in these cases a semiclassical interpretation for the functions in the exponents of the Wei–Norman factorization. The singularities of the functions appearing in the Wei–Norman factorization are related to the caustic points of Morse theory, and the expression of the evolution operator at the caustics is obtained using a limiting procedure, where the Fourier transform of the initial state appears along with the Guoy phase.

BYU Authors: Christopher B. Verhaaren, published in Phys. Rev. D

Recent anomalies in 8Be and 4He nuclear decays can be explained by postulating a fifth force mediated by a new boson X. The distributions of both transitions are consistent with the same X mass, 17 MeV, providing kinematic evidence for a single new particle explanation. In this work, we examine whether the new results also provide dynamical evidence for a new particle explanation, that is, whether the observed decay rates of both anomalies can be described by a single hypothesis for the X boson’s interactions. We consider the observed 8Be and 4He excited nuclei, as well as a 12C excited nucleus; together these span the possible JP quantum numbers up to spin 1 for excited nuclei. For each transition, we determine whether scalar, pseudoscalar, vector, or axial vector X particles can mediate the decay, and we construct the leading operators in a nuclear physics effective field theory that describes them. Assuming parity conservation, the scalar case is excluded and the pseudoscalar case is highly disfavored. Remarkably, however, the protophobic vector gauge boson, first proposed to explain only the 8Be anomaly, also explains the 4He anomaly within experimental uncertainties. We predict signal rates for other closely related nuclear measurements, which, if confirmed by the ATOMKI group and others, would provide overwhelming evidence that a fifth force has been discovered.

BYU Authors: Michael D. Joner and Denise C. Stephens, published in Astron. J.

We present the discoveries of KELT-25 b (TIC 65412605, TOI-626.01) and KELT-26 b (TIC 160708862, TOI-1337.01), two transiting companions orbiting relatively bright, early A stars. The transit signals were initially detected by the KELT survey and subsequently confirmed by Transiting Exoplanet Survey Satellite (TESS) photometry. KELT-25 b is on a 4.40 day orbit around the V = 9.66 star CD-24 5016 (Teff = 8280 K, M⋆ = 2.18 M⊙), while KELT-26 b is on a 3.34 day orbit around the V = 9.95 star HD 134004 (Teff = 8640, K, M⋆ = 1.93 M⊙), which is likely an Am star. We have confirmed the substellar nature of both companions through detailed characterization of each system using ground-based and TESS photometry, radial velocity measurements, Doppler tomography, and high-resolution imaging. For KELT-25, we determine a companion radius of RP = 1.64 RJ and a 3σ upper limit on the companion’s mass of ∼64 MJ. For KELT-26 b, we infer a planetary mass and radius of MP = 1.41 MJ  and RP = 1.94 RJ. From Doppler tomographic observations, we find KELT-26 b to reside in a highly misaligned orbit. This conclusion is weakly corroborated by a subtle asymmetry in the transit light curve from the TESS data. KELT-25 b appears to be in a well-aligned, prograde orbit, and the system is likely a member of the cluster Theia 449.