6 research outputs found
KELT-16b: A Highly Irradiated, Ultra-short Period Hot Jupiter Nearing Tidal Disruption
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/KELT-16. A global analysis of the system shows KELT-16 to be an F7V star with K and . The planet is a relatively high-mass inflated gas giant with density g cm-3, surface gravity , and K. The best-fitting linear ephemeris is and day. KELT-16b joins WASP-18b, -19b, -43b, -103b, and HATS-18b as the only giant transiting planets with P \u3c 1 day. Its ultra-short period and high irradiation make it a benchmark target for atmospheric studies by the Hubble Space Telescope, Spitzer, and eventually the James Webb Space Telescope. 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 ∼1.7 Roche radii from its host star, and could be tidally disrupted in as little as a few ×105 years (for a stellar tidal quality factor of ). Finally, the likely existence of a widely separated bound stellar companion in the KELT-16 system makes it possible that Kozai-Lidov (KL) oscillations played a role in driving KELT-16b inward to its current precarious orbit
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\u27s 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\u27s spin axis and its planet\u27s 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
KELT-16b: A Highly Irradiated, Ultra-short Period Hot Jupiter Nearing Tidal Disruption
We announce the discovery of KELT-16b, a highly irradiated, ultra-short
period hot Jupiter transiting the relatively bright () star TYC
2688-1839-1. A global analysis of the system shows KELT-16 to be an F7V star
with K, ,
[Fe/H] = -0.002, , and . The planet is a
relatively high mass inflated gas giant with , , density g cm, surface
gravity , and K. The best-fitting linear ephemeris is BJD and d.
KELT-16b joins WASP-18b, -19b, -43b, -103b, and HATS-18b as the only giant
transiting planets with 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 1.7 Roche radii from its
host star, and could be tidally disrupted in as little as a few
years (for a stellar tidal quality factor of ). 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.Comment: 16 pages, 18 Figures, 7 Tables, Accepted for publication in A
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