9 research outputs found
Constraints on Metastable Helium in the Atmospheres of WASP-69b and WASP-52b with Ultra-Narrowband Photometry
Infrared observations of metastable 2S helium absorption with ground- and
space-based spectroscopy are rapidly maturing, as this species is a unique
probe of exoplanet atmospheres. Specifically, the transit depth in the triplet
feature (with vacuum wavelengths near 1083.3 nm) can be used to constrain the
temperature and mass loss rate of an exoplanet's upper atmosphere. Here, we
present a new photometric technique to measure metastable 2S helium
absorption using an ultra-narrowband filter (full-width at half-maximum of
0.635 nm) coupled to a beam-shaping diffuser installed in the Wide-field
Infrared Camera (WIRC) on the 200-inch Hale Telescope at Palomar Observatory.
We use telluric OH lines and a helium arc lamp to characterize refractive
effects through the filter and to confirm our understanding of the filter
transmission profile. We benchmark our new technique by observing a transit of
WASP-69b and detect an excess absorption of % (11.1),
consistent with previous measurements after considering our bandpass. Then, we
use this method to study the inflated gas giant WASP-52b and place a
95th-percentile upper limit on excess absorption in our helium bandpass of
0.47%. Using an atmospheric escape model, we constrain the mass loss rate for
WASP-69b to be
() at 7,000 K
(12,000 K). Additionally, we set an upper limit on the mass loss rate of
WASP-52b at these temperatures of
(). These results show that
ultra-narrowband photometry can reliably quantify absorption in the metastable
helium feature.Comment: 17 pages, 8 figures (figures 1 and 2 are rasterized for arXiv file
size compliance), accepted to A
Constraints on Metastable Helium in the Atmospheres of WASP-69b and WASP-52b with Ultranarrowband Photometry
Infrared observations of metastable 2ÂłS helium absorption with ground- and space-based spectroscopy are rapidly maturing, as this species is a unique probe of exoplanet atmospheres. Specifically, the transit depth in the triplet feature (with vacuum wavelengths near 1083.3 nm) can be used to constrain the temperature and mass-loss rate of an exoplanet's upper atmosphere. Here, we present a new photometric technique to measure metastable 23S helium absorption using an ultranarrowband filter (FWHM 0.635 nm) coupled to a beam-shaping diffuser installed in the Wide-field Infrared Camera on the 200 inch Hale Telescope at Palomar Observatory. We use telluric OH lines and a helium arc lamp to characterize refractive effects through the filter and to confirm our understanding of the filter transmission profile. We benchmark our new technique by observing a transit of WASP-69b and detect an excess absorption of 0.498% ± 0.045% (11.1Ï), consistent with previous measurements after considering our bandpass. We then use this method to study the inflated gas giant WASP-52b and place a 95th percentile upper limit on excess absorption in our helium bandpass of 0.47%. Using an atmospheric escape model, we constrain the mass-loss rate for WASP-69b to be 5.25^(+0.65)_(â0.46) Ă 10â»âŽ M_J/Gyrâ»Âč (3.32^(+0.67)_(â0.56) Ă 10â»Âł M_J/Gyrâ»Âč) at 7000 K (12,000 K). Additionally, we set an upper limit on the mass-loss rate of WASP-52b at these temperatures of 2.1 Ă 10â»âŽ M_J/Gyrâ»Âč (2.1Ă10â»Âł M_J/Gyrâ»Âč) . These results show that ultranarrowband photometry can reliably quantify absorption in the metastable helium feature
Stability and detectability of exomoons orbiting HIP 41378 f, a temperate Jovian planet with an anomalously low apparent density
Moons orbiting exoplanets (âexomoonsâ) may hold clues about planet formation, migration, and habitability. In this work, we investigate the plausibility of exomoons orbiting the temperate (T eq = 294 K) giant (R = 9.2 R â) planet HIP 41378 f, which has been shown to have a low apparent bulk density of 0.09 g cmâ3 and a flat near-infrared transmission spectrum, hinting that it may possess circumplanetary rings. Given this planetâs long orbital period (P â 1.5 yr), it has been suggested that it may also host a large exomoon. Here, we analyze the orbital stability of a hypothetical exomoon with a satellite-to-planet mass ratio of 0.0123 orbiting HIP 41378 f. Combining a new software package, astroQTpy, with REBOUND and EqTide, we conduct a series of N-body and tidal migration simulations, demonstrating that satellites up to this size are largely stable against dynamical escape and collisions. We simulate the expected transit signal from this hypothetical exomoon and show that current transit observations likely cannot constrain the presence of exomoons orbiting HIP 41378 f, though future observations may be capable of detecting exomoons in other systems. Finally, we model the combined transmission spectrum of HIP 41378 f and a hypothetical moon with a low-metallicity atmosphere and show that the total effective spectrum would be contaminated at the âŒ10 ppm level. Our work not only demonstrates the feasibility of exomoons orbiting HIP 41378 f but also shows that large exomoons may be a source of uncertainty in future high-precision measurements of exoplanet systems
The TESS-Keck Survey. XI. Mass Measurements for Four Transiting sub-Neptunes orbiting K dwarf TOI-1246
Multi-planet systems are valuable arenas for investigating exoplanet architectures and comparing planetary siblings. TOI-1246 is one such system, with a moderately bright K dwarf (V=11.6, K=9.9) and four transiting sub-Neptunes identified by TESS with orbital periods of 4.31 d, 5.90 d, 18.66 d, and 37.92 d. We collected 130 radial velocity observations with Keck/HIRES and TNG/HARPS-N to measure planet masses. We refit the 14 sectors of TESS photometry to refine planet radii (2.97±0.06 Râ,2.47±0.08 Râ,3.46±0.09 Râ, 3.72±0.16 Râ), and confirm the four planets. We find that TOI-1246 e is substantially more massive than the three inner planets (8.1±1.1Mâ, 8.8±1.2Mâ, 5.3±1.7Mâ, 14.8±2.3Mâ). The two outer planets, TOI-1246 d and TOI-1246 e, lie near to the 2:1 resonance (Pe/Pd=2.03) and exhibit transit timing variations. TOI-1246 is one of the brightest four-planet systems, making it amenable for continued observations. It is one of only six systems with measured masses and radii for all four transiting planets. The planet densities range from 0.70±0.24 to 3.21±0.44g/cm3, implying a range of bulk and atmospheric compositions. We also report a fifth planet candidate found in the RV data with a minimum mass of 25.6 ± 3.6 Mâ. This planet candidate is exterior to TOI-1246 e with a candidate period of 93.8 d, and we discuss the implications if it is confirmed to be planetary in nature
The TESS-Keck Survey. XI. Mass Measurements for Four Transiting Sub-Neptunes Orbiting K Dwarf TOI-1246
Multiplanet systems are valuable arenas for investigating exoplanet architectures and comparing planetary siblings. TOI-1246 is one such system, with a moderately bright K dwarf (V = 11.6, K = 9.9) and four transiting sub-Neptunes identified by TESS with orbital periods of 4.31, 5.90, 18.66, and 37.92 days. We collected 130 radial velocity observations with Keck/HIRES and TNG/HARPS-N to measure planet masses. We refit the 14 sectors of TESS photometry to refine planet radii (2.97 +/- 0.06 R (circle plus), 2.47 +/- 0.08 R (circle plus), 3.46 +/- 0.09 R (circle plus), and 3.72 +/- 0.16 R (circle plus)) and confirm the four planets. We find that TOI-1246 e is substantially more massive than the three inner planets (8.1 +/- 1.1 M (circle plus), 8.8 +/- 1.2 M (circle plus), 5.3 +/- 1.7 M (circle plus), and 14.8 +/- 2.3 M (circle plus)). The two outer planets, TOI-1246 d and TOI-1246 e, lie near to the 2:1 resonance (P (e)/P ( d ) = 2.03) and exhibit transit-timing variations. TOI-1246 is one of the brightest four-planet systems, making it amenable for continued observations. It is one of only five systems with measured masses and radii for all four transiting planets. The planet densities range from 0.70 +/- 0.24 to 3.21 +/- 0.44 g cm(-3), implying a range of bulk and atmospheric compositions. We also report a fifth planet candidate found in the RV data with a minimum mass of 25.6 +/- 3.6 M (circle plus). This planet candidate is exterior to TOI-1246 e, with a candidate period of 93.8 days, and we discuss the implications if it is confirmed to be planetary in nature
The KELT Follow-up Network and Transit False-positive Catalog: Pre-vetted False Positives for TESS
The Kilodegree Extremely Little Telescope (KELT) project has been conducting
a photometric survey for transiting planets orbiting bright stars for over ten
years. The KELT images have a pixel scale of ~23"/pixel---very similar to that
of NASA's Transiting Exoplanet Survey Satellite (TESS)---as well as a large
point spread function, and the KELT reduction pipeline uses a weighted
photometric aperture with radius 3'. At this angular scale, multiple stars are
typically blended in the photometric apertures. In order to identify false
positives and confirm transiting exoplanets, we have assembled a follow-up
network (KELT-FUN) to conduct imaging with higher spatial resolution, cadence,
and photometric precision than the KELT telescopes, as well as spectroscopic
observations of the candidate host stars. The KELT-FUN team has followed-up
over 1,600 planet candidates since 2011, resulting in more than 20 planet
discoveries. Excluding ~450 false alarms of non-astrophysical origin (i.e.,
instrumental noise or systematics), we present an all-sky catalog of the 1,128
bright stars (6<V<10) that show transit-like features in the KELT light curves,
but which were subsequently determined to be astrophysical false positives
(FPs) after photometric and/or spectroscopic follow-up observations. The
KELT-FUN team continues to pursue KELT and other planet candidates and will
eventually follow up certain classes of TESS candidates. The KELT FP catalog
will help minimize the duplication of follow-up observations by current and
future transit surveys such as TESS.Comment: Accepted for publication in AJ, 21 pages, 12 figures, 7 table