11 research outputs found
Ground-based optical transmission spectrum of the hot Jupiter HAT-P-1b
Time-series spectrophotometric studies of exoplanets during transit using
ground-based facilities are a promising approach to characterize their
atmospheric compositions. We aim to investigate the transit spectrum of the hot
Jupiter HAT-P-1b. We compare our results to those obtained at similar
wavelengths by previous space-based observations. We observed two transits of
HAT-P-1b with the Gemini Multi-Object Spectrograph (GMOS) instrument on the
Gemini North telescope using two instrument modes covering the 320 - 800 nm and
520 - 950 nm wavelength ranges. We used time-series spectrophotometry to
construct transit light curves in individual wavelength bins and measure the
transit depths in each bin. We accounted for systematic effects. We addressed
potential photometric variability due to magnetic spots in the planet's host
star with long-term photometric monitoring. We find that the resulting transit
spectrum is consistent with previous Hubble Space Telescope (HST) observations.
We compare our observations to transit spectroscopy models that marginally
favor a clear atmosphere. However, the observations are also consistent with a
flat spectrum, indicating high-altitude clouds. We do not detect the Na
resonance absorption line (589 nm), and our observations do not have sufficient
precision to study the resonance line of K at 770 nm. We show that even a
single Gemini/GMOS transit can provide constraining power on the properties of
the atmosphere of HAT-P-1b to a level comparable to that of HST transit studies
in the optical when the observing conditions and target and reference star
combination are suitable. Our 520 - 950 nm observations reach a precision
comparable to that of HST transit spectra in a similar wavelength range of the
same hot Jupiter, HAT-P-1b. However, our GMOS transit between 320 - 800 nm
suffers from strong systematic effects and yields larger uncertainties.Comment: A&A, accepted, 16 pages, 8 figures, 5 table
A new method to correct for host star variability in multi-epoch observations of exoplanet transmission spectra
Transmission spectra of exoplanets orbiting active stars suffer from
wavelength-dependent effects due to stellar photospheric heterogeneity.
WASP-19b, an ultra-hot Jupiter (T 2100 K), is one such strongly
irradiated gas-giant orbiting an active solar-type star. We present optical
(520-900 nm) transmission spectra of WASP-19b obtained across eight epochs
using the Gemini Multi-Object Spectrograph (GMOS) on the Gemini-South
telescope. We apply our recently developed Gaussian Processes regression based
method to model the transit light curve systematics and extract the
transmission spectrum at each epoch. We find that WASP-19b's transmission
spectrum is affected by stellar variability at individual epochs. We report an
observed anticorrelation between the relative slopes and offsets of the spectra
across all epochs. This anticorrelation is consistent with the predictions from
the forward transmission models, which account for the effect of unocculted
stellar spots and faculae measured previously for WASP-19. We introduce a new
method to correct for this stellar variability effect at each epoch by using
the observed correlation between the transmission spectral slopes and offsets.
We compare our stellar variability corrected GMOS transmission spectrum with
previous contradicting MOS measurements for WASP-19b and attempt to reconcile
them. We also measure the amplitude and timescale of broadband stellar
variability of WASP-19 from TESS photometry, which we find to be consistent
with the effect observed in GMOS spectroscopy and ground-based broadband
photometric long-term monitoring. Our results ultimately caution against
combining multi-epoch optical transmission spectra of exoplanets orbiting
active stars before correcting each epoch for stellar variability.Comment: Accepted for publication in MNRA
Probing reflection from aerosols with the near-infrared dayside spectrum of WASP-80b
The presence of aerosols is intimately linked to the global energy budget and
the composition of a planet's atmospheres. Their ability to reflect incoming
light prevents energy from being deposited into the atmosphere, and they shape
spectra of exoplanets. We observed five near-infrared secondary eclipses of
WASP-80b with the Wide Field Camera 3 (WFC3) aboard the \textit{Hubble Space
Telescope} to provide constraints on the presence and properties of atmospheric
aerosols. We detect a broadband eclipse depth of \,ppm for WASP-80b.
We detect a higher planetary flux than expected from thermal emission alone at
, which hints toward the presence of reflecting aerosols on this
planet's dayside, indicating a geometric albedo of at 3. We
paired the WFC3 data with Spitzer data and explored multiple atmospheric models
with and without aerosols to interpret this spectrum. Albeit consistent with a
clear dayside atmosphere, we found a slight preference for near-solar
metallicities and for dayside clouds over hazes. We exclude soot haze formation
rates higher than g cms and tholin formation rates
higher than g cms at . We applied the same
atmospheric models to a previously published WFC3/Spitzer transmission spectrum
for this planet and found weak haze formation. A single soot haze formation
rate best fits both the dayside and the transmission spectra simultaneously.
However, we emphasize that no models provide satisfactory fits in terms of the
chi-square of both spectra simultaneously, indicating longitudinal
dissimilarity in the atmosphere's aerosol composition.Comment: Published in ApJ Letters (20 Oct 2023
Astrobites as a Community-led Model for Education, Science Communication, and Accessibility in Astrophysics
Support for early career astronomers who are just beginning to explore
astronomy research is imperative to increase retention of diverse practitioners
in the field. Since 2010, Astrobites has played an instrumental role in
engaging members of the community -- particularly undergraduate and graduate
students -- in research. In this white paper, the Astrobites collaboration
outlines our multi-faceted online education platform that both eases the
transition into astronomy research and promotes inclusive professional
development opportunities. We additionally offer recommendations for how the
astronomy community can reduce barriers to entry to astronomy research in the
coming decade
Updated Planetary Mass Constraints of the Young V1298 Tau System Using MAROON-X
The early K-type T-Tauri star, V1298 Tau (, ) hosts four transiting planets with radii ranging
from . The three inner planets have orbital periods of
while the outer planet's period is poorly constrained by
single transits observed with \emph{K2} and \emph{TESS}. Planets b, c, and d
are proto-sub-Neptunes that may be undergoing significant mass loss. Depending
on the stellar activity and planet masses, they are expected to evolve into
super-Earths/sub-Neptunes that bound the radius valley. Here we present results
of a joint transit and radial velocity (RV) modelling analysis, which includes
recently obtained \emph{TESS} photometry and MAROON-X RV measurements. Assuming
circular orbits, we obtain a low-significance () RV detection
of planet c implying a mass of and a
conservative upper limit of . For planets b and d, we
derive upper limits of and . For planet e, plausible discrete periods of are ruled out at a level while seven solutions with
are consistent with the most probable
solution within . Adopting the most
probable solution yields a RV detection with mass a of
. Comparing the updated mass and radius constraints
with planetary evolution and interior structure models shows that planets b, d,
and e are consistent with predictions for young gas-rich planets and that
planet c is consistent with having a water-rich core with a substantial
( by mass) H envelope.Comment: 18 pages, 13 figures, accepted for publication in A
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Measuring the variability of directly imaged exoplanets using vector Apodizing Phase Plates combined with ground-based differential spectrophotometry
Clouds and other features in exoplanet and brown dwarf atmospheres cause variations in brightness as they rotate in and out of view. Ground-based instruments reach the high contrasts and small inner working angles needed to monitor these faint companions, but their small fields of view lack simultaneous photometric references to correct for non-astrophysical variations. We present a novel approach for making ground-based light curves of directly imaged companions using high-cadence differential spectrophotometric monitoring, where the simultaneous reference is provided by a double-grating 360○ vector Apodizing Phase Plate (dgvAPP360) coronagraph. The dgvAPP360 enables high-contrast companion detections without blocking the host star, allowing it to be used as a simultaneous reference. To further reduce systematic noise, we emulate exoplanet transmission spectroscopy, where the light is spectrally dispersed and then recombined into white-light flux. We do this by combining the dgvAPP360 with the infrared Arizona Lenslets for Exoplanet Spectroscopy integral field spectrograph on the Large Binocular Telescope Interferometer. To demonstrate, we observed the red companion HD 1160 B (separation ∼780 mas) for one night, and detec
Reproduction package for "Probing reflection from aerosols with the near-infrared dayside spectrum of WASP-80b"
<p>This is a basic reproduction package for the paper "Probing reflection from</p><p>aerosols with the near-infrared dayside spectrum of WASP-80b"</p><p>by [Jacobs, B.; Désert, J. -M.; Gao P. et al. (2023)](https://doi.org/10.3847/2041-8213/acfee9).</p><p>Abstract:</p><p>The presence of aerosols is intimately linked to the global energy budget and the composition of a planet's atmospheres. Their ability to reflect incoming light prevents energy from being deposited into the atmosphere, and they shape spectra of exoplanets. We observed five near-infrared secondary eclipses of WASP-80b</p><p>with the Wide Field Camera 3 (WFC3) aboard the Hubble Space Telescope to provide constraints on the presence and properties of atmospheric aerosols.</p><p>We detect a broadband eclipse depth of 34\pm10 ppm for WASP-80b. We detect a higher planetary flux than expected from thermal emission alone at 1.6 sigma, which hints toward the presence of reflecting aerosols on this planet's dayside, indicating a geometric albedo of A_g<0.33 at 3 sigma.</p><p>We paired the WFC3 data with Spitzer data and explored multiple atmospheric models with and without aerosols to interpret this spectrum.</p><p>Albeit consistent with a clear dayside atmosphere, we found a slight preference for near-solar metallicities and for dayside clouds over hazes. We exclude soot haze formation rates higher than 10^{-10.7} g cm^{-2} s^{-1} and tholin formation rates higher than 10^{-12.0} g cm^{-2} s^{-1} at 3 sigma.</p><p>We applied the same atmospheric models to a previously published WFC3/Spitzer transmission spectrum for this planet and found weak haze formation.</p><p>A single soot haze formation rate best fits both the dayside and the transmission spectra simultaneously. However, we emphasize that no models provide satisfactory fits in terms of the chi-square of both spectra simultaneously, indicating longitudinal dissimilarity in the atmosphere's aerosol composition.</p>
Reproduction package for the paper "Measuring the variability of directly imaged exoplanets using vector Apodizing Phase Plates combined with ground-based differential spectrophotometry"
This is a basic reproduction package for the paper "Measuring the variability of directly imaged exoplanets using vector Apodizing Phase Plates combined with ground-based differential spectrophotometry" by Sutlieff et al. (2023). It aims to provide the most important data products to check and reproduce the main results of the paper
Astrobites as a Community-led Model for Education, Science Communication, and Accessibility in Astrophysics
Support for early career astronomers who are just beginning to explore astronomy research is imperative to increase retention of diverse practitioners in the field. Since 2010, Astrobites has played an instrumental role in engaging members of the community -- particularly undergraduate and graduate students -- in research. In this white paper, the Astrobites collaboration outlines our multi-faceted online education platform that both eases the transition into astronomy research and promotes inclusive professional development opportunities. We additionally offer recommendations for how the astronomy community can reduce barriers to entry to astronomy research in the coming decade
Astrobites as a Community-led Model for Education, Science Communication, and Accessibility in Astrophysics
Support for early career astronomers who are just beginning to explore astronomy research is imperative to increase retention of diverse practitioners in the field. Since 2010, Astrobites has played an instrumental role in engaging members of the community -- particularly undergraduate and graduate students -- in research. In this white paper, the Astrobites collaboration outlines our multi-faceted online education platform that both eases the transition into astronomy research and promotes inclusive professional development opportunities. We additionally offer recommendations for how the astronomy community can reduce barriers to entry to astronomy research in the coming decade