Penev, Kaloyan
Permanent URI for this collectionhttps://hdl.handle.net/10735.1/6247
Kaloyan Penev joined the UTD faculty as an Assistant Professor of Physics in 2017. His research interests include:
- Extrasolar planet detection and orbital dynamics
- Searching for transiting extrasolar planets using small robotic telescopes
- High precision photometry from space and from the ground
- Orbital dynamics of extrasolar planetary systems
- Astrophysical probes of tidal dissipation in giant planets and low mass stars
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Browsing Penev, Kaloyan by Author "Brahm, R."
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Item An Eccentric Massive Jupiter Orbiting a Subgiant on a 9.5-day Period Discovered in the Transiting Exoplanet Survey Satellite Full Frame Images(Institute of Physics Publishing, 2019-05) Rodriguez, J. E.; Quinn, S. N.; Huang, C. X.; Vanderburg, A.; Penev, Kaloyan; Brahm, R.; Jordán, A.; 0000-0003-4464-1371 (Penev, K); Penev, KaloyanWe report the discovery of TOI-172 b from the Transiting Exoplanet Survey Satellite (TESS) mission, a massive hot Jupiter transiting a slightly evolved G star with a 9.48-day orbital period. This is the first planet to be confirmed from analysis of only the TESS full frame images, because the host star was not chosen as a two-minute cadence target. From a global analysis of the TESS photometry and follow-up observations carried out by the TESS Follow-up Observing Program Working Group, TOI-172 (TIC 29857954) is a slightly evolved star with an effective temperature of T_{eff} = 5645 ± 50 K, a mass of M_{∗} = 1.128_{-0.061} ^{+0.065} M ⊙, radius of R_{∗} = 1.777_{-0.044} ^{+0.047} R ⊙, a surface gravity of log g_{∗} = 3.993 _{-0.028} ^{+0.027}, and an age of 7.4 _{-1.5} ^{+1.6}. Its planetary companion (TOI-172 b) has a radius of R _{P} = 0.965 _{-0.029} ^{+0.032} R_{J}, a mass of M _{P} = 5.42 _{-0.20} ^{+0.22} M _{J}, and is on an eccentric orbit (e = 0.3806 _{-0.0090} ^{+0.0093} ). TOI-172 b is one of the few known massive giant planets on a highly eccentric short-period orbit. Future study of the atmosphere of this planet and its system architecture offer opportunities to understand the formation and evolution of similar systems. © 2019. The American Astronomical Society. All rights reserved..Item HATS-39b, HATS-40b, HATS-41b, and HATS-42b: Three Inflated Hot Jupiters and a Super-Jupiter Transiting F Stars(Oxford Univ Press) Bento, J.; Hartman, J. D.; Bakos, G. A.; Bhatti, W.; Csubry, Z.; Penev, Kaloyan; Bayliss, D.; de Val-Borro, M.; Zhou, G.; Brahm, R.; Espinoza, N.; Rabus, M.; Jordan, A.; Suc, V.; Ciceri, S.; Sarkis, P.; Henning, T.; Mancini, L.; Tinney, C. G.; Wright, D. J.; Durkan, S.; Tan, T. G.; Lazar, J.; Papp, I.; Sari, P.; 0000-0003-4464-1371 (Penev, K); Penev, KaloyanWe report the discovery of four transiting hot Jupiters from the HATSouth survey: HATS39b, HATS-40b, HATS-41b, and HATS-42b. These discoveries add to the growing number of transiting planets orbiting moderately bright (12.5 ≲ V ≲ 13.7) F dwarf stars on short (2-5 d) periods. The planets have similar radii, ranging from 1.33{_{0.20}^{+0.29}} R_J for HATS-41b to 1.58{_{-0.12} ^{+0.16}} R_J for HATS-40b. Their masses and bulk densities, however, span more than an order of magnitude. HATS-39b has a mass of 0.63 ± 0.13M(J), and an inflated radius of 1.57 ± 0.12 R-J, making it a good target for future transmission spectroscopic studies. HATS41b is a very massive 9.7 ± 1.6M_J planet and one of only a few hot Jupiters found to date with a mass over 5 M_J. This planet orbits the highest metallicity star ([Fe/H] = 0.470 ± 0.010) known to host a transiting planet and is also likely on an eccentric orbit. The high mass, coupled with a relatively young age (1.34{_{-0.51} ^{+0.31}} Gyr) for the host star, is a factor that may explain why this planet's orbit has not yet circularized.Item HATS-60b-HATS-69b: 10 Transiting Planets from HATSouth(IOP Publishing Ltd, 2019-02) Hartman, J. D.; Bakos, G. A.; Bayliss, D.; Bento, J.; Bhatti, W.; Brahm, R.; Csubry, Z.; Espinoza, N.; Penev, Kaloyan; Penev, KaloyanWe report the discovery of 10 transiting extrasolar planets by the HATSouth survey. The planets range in mass from the super-Neptune HATS-62b, with Mₚ < 0.179 Mⱼ, to the super-Jupiter HATS-66b, with Mₚ = 5.33 Mⱼ, and in size from the Saturn HATS-69b, with Rₚ = 0.94 Rⱼ, to the inflated Jupiter HATS-67b, with Rₚ = 1.69 Rⱼ. The planets have orbital periods between 1.6092 days (HATS-67b) and 7.8180 days (HATS-61b). The hosts are dwarf stars with masses ranging from 0.89 M⊙(HATS-69) to 1.56 M⊙ (HATS-64) and have apparent magnitudes between V = 12.276 ± 0.020 mag (HATS-68) and V = 14.095 ± 0.030 mag (HATS-66). The super-Neptune HATS-62b is the least massive planet discovered to date with a radius larger than Jupiter. Based largely on the Gaia DR2 distances and broadband photometry, we identify three systems (HATS-62, HATS-64, and HATS-65) as having possible unresolved binary star companions. We discuss in detail our methods for incorporating the Gaia DR2 observations into our modeling of the system parameters and into our blend analysis procedures.Item Hats-70b: A 13 MJ Brown Dwarf Transiting an A Star(IOP Publishing Ltd, 2019-01-02) Zhou, G.; Bakos, G. A.; Bayliss, D.; Bento, J.; Bhatti, W.; Brahm, R.; Csubry, Z.; Espinoza, N.; Hartman, J. D.; Henning, T.; Jordan, A.; Mancini, L.; Penev, Kaloyan; Rabus, M.; Sarkis, P.; Suc, V.; de Val-Borro, M.; Rodriguez, J. E.; Osip, D.; Kedziora-Chudczer, L.; Bailey, J.; Tinney, C. G.; Durkan, S.; Lazar, J.; Papp, I.; Sari, P.; 0000-0003-4464-1371 (Penev, K); Penev, KaloyanWe report the discovery of HATS-70b, a transiting brown dwarf at the deuterium burning limit. HATS-70b has a mass of M_{p} = 12.9{{-1.6}^{+1.8} M_{Jup} and a radius of R_{p} = 1.384_{{-0.074} {+0.079}} R_{Jup}, residing in a close-in orbit with a period of 1.89 days. The host star is a M⁎ = 1.78 ± 0.12 M_⊙ A star rotating at v sin I⁎ = 40.61{_{-0.35}}^{+0.32}} km s⁻¹ , enabling us to characterize the spectroscopic transit of the brown dwarf via Doppler tomography. We find that HATS-70b, like other massive planets and brown dwarfs previously sampled, orbits in a low projected-obliquity orbit with λ = {_{8.9}^{5.6°}}. The low obliquities of these systems is surprising given all brown dwarf and massive planets with obliquities measured orbit stars hotter than the Kraft break. This trend is tentatively inconsistent with dynamically chaotic migration for systems with massive companions, though the stronger tidal influence of these companions makes it difficult to draw conclusions on the primordial obliquity distribution of this population. We also introduce a modeling scheme for planets around rapidly rotating stars, accounting for the influence of gravity darkening on the derived stellar and planetary parameters.