58 research outputs found
Colour-magnitude diagrams of transiting exoplanets
Colour-Magnitude Diagrams provide a simple way of comparing populations of similar objects; and when well populated with precise measurements they allow quick inferences to be made about the bulk properties of an astronomic object simply from its proximity on a diagram to other objects. We present here a Python toolkit which allows a user to produce colour-magnitude diagrams of transiting exoplanets, comparing planets to populations of ultra-cool dwarfs and directly imaged exoplanets, to models of planetary atmospheres, and to other transiting exoplanets. Using a selection of near- and mid-infrared colour-magnitude diagrams, we show how outliers can be identified for further investigation, and how emerging sub-populations can be identified. Additionally, we present evidence that observed differences in the Spitzer’s 4.5m flux, between irradiated Jupiters, and field field brown dwarfs, might be attributed to Phosphine, which is susceptible to photolysis. If confirmed, this may negate the need for thermal inversions to explain eclipse measurements. We extend this reasoning to other objects and speculate that the anomalously low 4.5m flux flux of the nightside of HD189733b and the daysides of GJ 436b and GJ 3470b might be caused by Phosphine absorption. Finally, we use our toolkit to include Hubble WFC3 spectra, creating a new photometric band called the ‘Water band’ (W-band) in the process. We show that the colour index [W-H] can be used to constrain the C/O ratio of exoplanets, showing that future observations with JWST and ARIEL will be able to distinguish these populations if they exist, and select members for future follow-up.
The work presented in this thesis is being prepared for publication in a paper on which I will be first author. The abstract above is lifted verbatim from the current manuscript of that paper
Colour-magnitude diagrams of transiting Exoplanets -- III. A public code, nine strange planets, and the role of Phosphine
Colour-Magnitude Diagrams provide a convenient way of comparing populations
of similar objects. When well populated with precise measurements, they allow
quick inferences to be made about the bulk properties of an astronomic object
simply from its proximity on a diagram to other objects. We present here a
Python toolkit which allows a user to produce colour-magnitude diagrams of
transiting exoplanets, comparing planets to populations of ultra-cool dwarfs,
of directly imaged exoplanets, to theoretical models of planetary atmospheres,
and to other transiting exoplanets. Using a selection of near- and mid-infrared
colour-magnitude diagrams, we show how outliers can be identified for further
investigation, and how emerging sub-populations can be identified.
Additionally, we present evidence that observed differences in the
\textit{Spitzer}'s 4.5\mu m flux, between irradiated Jupiters, and field brown
dwarfs, might be attributed to phosphine, which is susceptible to photolysis.
The presence of phosphine in low irradiation environments may negate the need
for thermal inversions to explain eclipse measurements. We speculate that the
anomalously low 4.5\mu m flux flux of the nightside of HD 189733b and the
daysides of GJ 436b and GJ 3470b might be caused by phosphine absorption.
Finally, we use our toolkit to include \textit{Hubble} WFC3 spectra, creating a
new photometric band called the `Water band' (\textit{W}-band) in the
process. We show that the colour index [\textit{W-H}] can be used to
constrain the C/O ratio of exoplanets, showing that future observations with
\textit{JWST} and \textit{Ariel} will be able to distinguish these populations
if they exist, and select members for future follow-up.Comment: Accepted for publication in MNRA
HD 28109 hosts a trio of transiting Neptunian planets including a near-resonant pair, confirmed by ASTEP from Antarctica
We report on the disco v ery and characterization of three planets orbiting the F8 star HD 28109, which sits comfortably in TESS ’s continuous viewing zone. The two outer planets have periods of 56 . 0067 ±0 . 0003 d and 84 . 2597 + 0 . 0010 −0 . 0008 d, which implies a period ratio very close to that of the first-order 3:2 mean motion resonance, exciting transit timing variations (TTVs) of up to 60 min. These two planets were first identified by TESS , and we identified a third planet in the TESS photometry with a period of 22 . 8911 ±0 . 0004 d. We confirm the planetary nature of all three planetary candidates using ground-based photometry from Hazelwood , ASTEP , and LCO , including a full detection of the ∼9 h transit of HD 28109 c from Antarctica. The radii of the three planets are R b = 2 . 199 + 0 . 098 −0 . 10 R ⊕, R c = 4 . 23 ±0 . 11 R ⊕, and R d = 3 . 25 ±0 . 11 R ⊕; we characterize their masses using TTVs and precise radial velocities from ESPRESSO and HARPS, and find them to be M b = 18 . 5 + 9 . 1 −7 . 6 M ⊕, M c = 7 . 9 + 4 . 2 −3 . 0 M ⊕, and M d = 5 . 7 + 2 . 7 −2 . 1 M ⊕, making planet b a dense, massive planet while c and d are both underdense. We also demonstrate that the two outer planets are ripe for atmospheric characterization using transmission spectroscopy, especially given their position in the CVZ of James Webb Space Telescope . The data obtained to date are consistent with resonant (librating) and non-resonant (circulating) solutions; additional observations will show whether the pair is actually locked in resonance or just near-resonant.French polar agency IPEV ANR-15-IDEX-01
French polar agency PNRA ANR-15-IDEX-01Italian polar agency IPEV ANR-15-IDEX-01
Italian polar agency PNRA ANR-15-IDEX-01NASA Exoplanet Exploration Program
NASA's Science Mission DirectorateEuropean Organisation for Astronomical Research in the Southern Hemisphere 0102.C-0503(A)National Science Foundation (NSF)European Space Agency
European CommissionSwiss National Science Foundation (SNSF)European CommissionEuropean Research Council (ERC) 803193/BEBOPUK Research & Innovation (UKRI)Science & Technology Facilities Council (STFC)Science and Technology Development Fund (STDF) ST/S00193X/1Fondazione CRT 2018.232
Small body harvest with the Antarctic Search for Transiting Exoplanets (ASTEP) project
Small Solar system bodies serve as pristine records that have been minimally
altered since their formation. Their observations provide valuable information
regarding the formation and evolution of our Solar system. Interstellar objects
(ISOs) can also provide insight on the formation of exoplanetary systems and
planetary system evolution as a whole. In this work, we present the application
of our framework to search for small Solar system bodies in exoplanet transit
survey data collected by the Antarctic Search for Transiting ExoPlanets (ASTEP)
project. We analysed data collected during the Austral winter of 2021 by the
ASTEP 400 telescope located at the Concordia Station, at Dome C, Antarctica. We
identified 20 known objects from dynamical classes ranging from Inner Main-belt
asteroids to one comet. Our search recovered known objects down to a magnitude
of = 20.4 mag, with a retrieval rate of 80% for objects with
20 mag. Future work will apply the pipeline to archival ASTEP data that
observed fields for periods of longer than a few hours to treat them as
deep-drilling datasets and reach fainter limiting magnitudes for slow-moving
objects, on the order of 23-24 mag.Comment: Accepted for publication in MNRAS (Monthly Notices of the Royal
Astronomical Society), 9 pages, 8 figure
New methods for radial-velocity measurements of double-lined binaries, and detection of a circumbinary planet orbiting TIC 172900988
Ongoing ground-based radial-velocity observations seeking to detect circumbinary planets focus on single-lined binaries even though over 9 in every 10 binary systems in the solar neighbourhood are double lined. Double-lined binaries are on average brighter, and should in principle yield more precise radial velocities. However, as the two stars orbit one another, they produce a time-varying blending of their weak spectral lines. This makes an accurate measure of radial velocities difficult, producing a typical scatter of . This extra noise prevents the detection of most orbiting circumbinary planets. We develop two new data-driven approaches to disentangle the two stellar components of a double-lined binary, and extract accurate and precise radial velocities. Both approaches use a Gaussian process regression, with the first one working in the spectral domain, whereas the second works on cross-correlated spectra. We apply our new methods to TIC 172900988, a proposed circumbinary system with a double-lined binary, and detect a circumbinary planet with an orbital period of , different than previously proposed. We also measure a significant residual scatter, which we speculate is caused by stellar activity. We show that our two data-driven methods outperform the traditionally used TODCOR and TODMOR, for that particular binary system
An M dwarf accompanied by a close-in giant orbiter with SPECULOOS
In the last decade, a dozen close-in giant planets have been discovered
orbiting stars with spectral types ranging from M0 to M4, a mystery since known
formation pathways do not predict the existence of such systems. Here, we
confirm TOI-4860 b, a Jupiter-sized planet orbiting an M4.5 host, a star at the
transition between fully and partially convective interiors. First identified
with TESS data, we validate the transiting companion's planetary nature through
multicolour photometry from the TRAPPIST-South/North, SPECULOOS, and MuSCAT3
facilities. Our analysis yields a radius of for
the planet, a mass of for the star, and an orbital period of
1.52 d. Using the newly commissioned SPIRIT InGaAs camera at the
SPECULOOS-South Observatory, we collect infrared photometry in zYJ that spans
the time of secondary eclipse. These observations do not detect a secondary
eclipse, placing an upper limit on the brightness of the companion. The
planetary nature of the companion is further confirmed through high-resolution
spectroscopy obtained with the IRD spectrograph at Subaru Telescope, from which
we measure a mass of . Based on its overall
density, TOI-4860 b appears to be rich in heavy elements, like its host star.Comment: Accepted for publication in MNRAS Letter
A massive hot Jupiter orbiting a metal-rich early-M star discovered in the TESS full frame images
Observations and statistical studies have shown that giant planets are rare
around M dwarfs compared with Sun-like stars. The formation mechanism of these
extreme systems remains under debate for decades. With the help of the TESS
mission and ground based follow-up observations, we report the discovery of
TOI-4201b, the most massive and densest hot Jupiter around an M dwarf known so
far with a radius of and a mass of ,
about 5 times heavier than most other giant planets around M dwarfs. It also
has the highest planet-to-star mass ratio () among such
systems. The host star is an early-M dwarf with a mass of $0.61\pm0.02\
M_{\odot}0.63\pm0.02\ R_{\odot}0.52\pm 0.08$ dex). However, interior
structure modeling suggests that its planet TOI-4201b is metal-poor, which
challenges the classical core-accretion correlation of stellar-planet
metallicity, unless the planet is inflated by additional energy sources.
Building on the detection of this planet, we compare the stellar metallicity
distribution of four planetary groups: hot/warm Jupiters around G/M dwarfs. We
find that hot/warm Jupiters show a similar metallicity dependence around G-type
stars. For M dwarf host stars, the occurrence of hot Jupiters shows a much
stronger correlation with iron abundance, while warm Jupiters display a weaker
preference, indicating possible different formation histories.Comment: 21 pages, 11 figures, 4 tables, submitted to A
Three long period transiting giant planets from TESS
We report the discovery and orbital characterization of three new transiting
warm giant planets. These systems were initially identified as presenting
single transit events in the light curves generated from the full frame images
of the Transiting Exoplanet Survey Satellite (TESS). Follow-up radial velocity
measurements and additional light curves were used to determine the orbital
periods and confirm the planetary nature of the candidates. The planets orbit
slightly metal-rich late F- and early G-type stars. We find that TOI 4406b has
a mass of = 0.30 0.04 , a radius of = 1.00 0.02
, and a low eccentricity orbit (e=0.15 0.05) with a period of P=
30.08364 0.00005 d . TOI 2338b has a mass of = 5.98 0.20
, a radius of = 1.00 0.01 , and a highly eccentric orbit (e=
0.676 0.002 ) with a period of P= 22.65398 0.00002 d . Finally, TOI
2589b has a mass of = 3.50 0.10 , a radius of = 1.08
0.03 , and an eccentric orbit (e = 0.522 0.006 ) with a
period of P= 61.6277 0.0002 d . TOI 4406b and TOI 2338b are enriched in
metals compared to their host stars, while the structure of TOI 2589b is
consistent with having similar metal enrichment to its host star.Comment: 24 pages, 16 figures, accepted in A
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