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 precise 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.
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 precise 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.
We have measured the Sunyaev Zel'dovich (SZ) effect for a sample of ten strong lensing selected galaxy clusters using the Sunyaev Zel'dovich Array (SZA). The SZA is sensitive to structures on spatial ...scales of a few arcminutes, while the strong lensing mass modeling constrains the mass at small scales (typically < 30"). Combining the two provides information about the projected concentrations of the strong lensing clusters. The Einstein radii we measure are twice as large as expected given the masses inferred from SZ scaling relations. A Monte Carlo simulation indicates that a sample randomly drawn from the expected distribution would have a larger median Einstein radius than the observed clusters about 3% of the time. The implied overconcentration has been noted in previous studies with smaller samples of lensing clusters. It persists for this sample, with the caveat that this could result from a systematic effect such as if the gas fractions of the strong lensing clusters are substantially below what is expected.
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