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تسجيل مستخدم جديدKELT-1b: A Strongly Irradiated, Highly Inflated, Short Period, 27 Jupiter-mass Companion Transiting a mid-F Star
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We present the discovery of KELT-1b, the first transiting low-mass companion from the wide-field Kilodegree Extremely Little Telescope-North (KELT-North) survey. The V=10.7 primary is a mildly evolved, solar-metallicity, mid-F star. The companion is a low-mass brown dwarf or super-massive planet with mass of 27.23+/-0.50 MJ and radius of 1.110+0.037-0.024 RJ, on a very short period (P=1.21750007) circular orbit. KELT-1b receives a large amount of stellar insolation, with an equilibrium temperature assuming zero albedo and perfect redistribution of 2422 K. Upper limits on the secondary eclipse depth indicate that either the companion must have a non-zero albedo, or it must experience some energy redistribution. Comparison with standard evolutionary models for brown dwarfs suggests that the radius of KELT-1b is significantly inflated. Adaptive optics imaging reveals a candidate stellar companion to KELT-1, which is consistent with an M dwarf if bound. The projected spin-orbit alignment angle is consistent with zero stellar obliquity, and the vsini of the primary is consistent with tidal synchronization. Given the extreme parameters of the KELT-1 system, we expect it to provide an important testbed for theories of the emplacement and evolution of short-period companions, and theories of tidal dissipation and irradiated brown dwarf atmospheres.
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We announce the discovery of KELT-16b, a highly irradiated, ultra-short period hot Jupiter transiting the relatively bright ($V = 11.7$) star TYC 2688-1839-1. A global analysis of the system shows KELT-16 to be an F7V star with $T_textrm{eff} = 6236p
m54$ K, $log{g_star} = 4.253_{-0.036}^{+0.031}$, [Fe/H] = -0.002$_{-0.085}^{+0.086}$, $M_star = 1.211_{-0.046}^{+0.043} M_odot$, and $R_star = 1.360_{-0.053}^{+0.064} R_odot$. The planet is a relatively high mass inflated gas giant with $M_textrm{P} = 2.75_{-0.15}^{+0.16} M_textrm{J}$, $R_textrm{P} = 1.415_{-0.067}^{+0.084} R_textrm{J}$, density $rho_textrm{P} = 1.20pm0.18$ g cm$^{-3}$, surface gravity $log{g_textrm{P}} = 3.530_{-0.049}^{+0.042}$, and $T_textrm{eq} = 2453_{-47}^{+55}$ K. The best-fitting linear ephemeris is $T_textrm{C} = 2457247.24791pm0.00019$ BJD$_{tdb}$ and $P = 0.9689951 pm 0.0000024$ d. KELT-16b joins WASP-18b, -19b, -43b, -103b, and HATS-18b as the only giant transiting planets with $P < 1$ day. Its ultra-short period and high irradiation make it a benchmark target for atmospheric studies by HST, Spitzer, and eventually JWST. For example, as a hotter, higher mass analog of WASP-43b, KELT-16b may feature an atmospheric temperature-pressure inversion and day-to-night temperature swing extreme enough for TiO to rain out at the terminator. KELT-16b could also join WASP-43b in extending tests of the observed mass-metallicity relation of the Solar System gas giants to higher masses. KELT-16b currently orbits at a mere $sim$ 1.7 Roche radii from its host star, and could be tidally disrupted in as little as a few $times 10^{5}$ years (for a stellar tidal quality factor of $Q_* = 10^5$). Finally, the likely existence of a widely separated bound stellar companion in the KELT-16 system makes it possible that Kozai-Lidov oscillations played a role in driving KELT-16b inward to its current precarious orbit.
We report the discovery of KELT-12b, a highly inflated Jupiter-mass planet transiting a mildly evolved host star. We identified the initial transit signal in the KELT-North survey data and established the planetary nature of the companion through pre
cise follow-up photometry, high-resolution spectroscopy, precise radial velocity measurements, and high-resolution adaptive optics imaging. Our preferred best-fit model indicates that the $V = 10.64$ host, TYC 2619-1057-1, has $T_{rm eff} = 6278 pm 51$ K, $log{g_star} = 3.89^{+0.054}_{-0.051}$, and [Fe/H] = $0.19^{+0.083}_{-0.085}$, with an inferred mass $M_{star} = 1.59^{+0.071}_{-0.091} M_odot$ and radius $R_star = 2.37 pm 0.18 R_odot$. The planetary companion has $M_{rm P} = 0.95 pm 0.14 M_{rm J}$, $R_{rm P} = 1.79^{+0.18}_{-0.17} R_{rm J}$, $log{g_{rm P}} = 2.87^{+0.097}_{-0.098}$, and density $rho_{rm P} = 0.21^{+0.075}_{-0.054}$ g cm$^{-3}$, making it one of the most inflated giant planets known. The time of inferior conjunction in ${rm BJD_{TDB}}$ is $2457088.692055 pm 0.0009$ and the period is $P = 5.0316144 pm 0.0000306$ days. Despite the relatively large separation of $sim0.07$ AU implied by its $sim 5.03$-day orbital period, KELT-12b receives significant flux of $2.93^{+0.33}_{-0.30} times 10^9$ erg s$^{-1}$ cm$^{-2}$ from its host. We compare the radii and insolations of transiting gas-giant planets around hot ($T_{rm eff} geq 6250$ 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 (TESS) to search for inflated giants in longer-period orbits.
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te F star with M_* = 1.278 (-0.061, +0.063) M_sun, R_* = 1.472 (-0.067, +0.065) R_sun, T_eff = 6306 (-49, +50) K, log(g) = 4.209 (-0.031, +0.033), and [Fe/H] = 0.044 (-0.082, +0.080), and has a likely proper motion companion. KELT-3b is the third transiting exoplanet discovered by the KELT survey, and is orbiting one of the 20 brightest known transiting planet host stars, making it a promising candidate for detailed characterization studies. Although we infer that KELT-3 is significantly evolved, a preliminary analysis of the stellar and orbital evolution of the system suggests that the planet has likely always received a level of incident flux above the empirically-identified threshold for radius inflation suggested by Demory & Seager (2011).
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