75 research outputs found
Telluric correction in the near-infrared: Standard star or synthetic transmission?
Context. The atmospheric absorption of the Earth is an important limiting
factor for ground-based spectroscopic observations and the near-infrared and
infrared regions are the most affected. Several software packages that produce
a synthetic atmospheric transmission spectrum have been developed to correct
for the telluric absorption; these are Molecfit, TelFit, and TAPAS. Aims. Our
goal is to compare the correction achieved using these three telluric
correction packages and the division by a telluric standard star. We want to
evaluate the best method to correct near-infrared high-resolution spectra as
well as the limitations of each software package and methodology. Methods. We
applied the telluric correction methods to CRIRES archival data taken in the J
and K bands. We explored how the achieved correction level varies depending on
the atmospheric T-P profile used in the modelling, the depth of the atmospheric
lines, and the molecules creating the absorption. Results. We found that the
Molecfit and TelFit corrections lead to smaller residuals for the water lines.
The standard star method corrects best the oxygen lines. The Molecfit package
and the standard star method corrections result in global offsets always below
0.5% for all lines; the offset is similar with TelFit and TAPAS for the H2O
lines and around 1% for the O2 lines. All methods and software packages result
in a scatter between 3% and 7% inside the telluric lines. The use of a tailored
atmospheric profile for the observatory leads to a scatter two times smaller,
and the correction level improves with lower values of precipitable water
vapour. Conclusions. The synthetic transmission methods lead to an improved
correction compared to the standard star method for the water lines in the J
band with no loss of telescope time, but the oxygen lines were better corrected
by the standard star method.Comment: 18 pages, 13 figures, Accepted to A&
Discovery of a massive giant planet with extreme density around a sub-giant star TOI-4603
We present the discovery of a transiting massive giant planet around
TOI-4603, a sub-giant F-type star from NASA's Transiting Exoplanet Survey
Satellite (TESS). The newly discovered planet has a radius of
, and an orbital period of
days. Using radial velocity measurements with
the PARAS {and TRES} spectrographs, we determined the planet's mass to be
, resulting in a bulk density of
g . This makes it one of the few massive giant
planets with extreme density and lies in the transition mass region of massive
giant planets and low-mass brown dwarfs, an important addition to the
population of less than five objects in this mass range. The eccentricity of
and an orbital separation of AU from its host
star suggest that the planet is likely undergoing high eccentricity tidal (HET)
migration. We find a fraction of heavy elements of and
metal enrichment of the planet () of .
Detection of such systems will offer us to gain valuable insights into the
governing mechanisms of massive planets and improve our understanding of their
dominant formation and migration mechanisms.Comment: accepted for publication in A&A Letter
Transmission spectroscopy of the ultra-hot Jupiter MASCARA-4 b: disentangling the hydrostatic and exospheric regimes of ultra-hot Jupiters
Stars and planetary system
TESS Duotransit Candidates from the Southern Ecliptic Hemisphere
Discovering transiting exoplanets with long orbital periods allows us to
study warm and cool planetary systems with temperatures similar to the planets
in our own Solar system. The TESS mission has photometrically surveyed the
entire Southern Ecliptic Hemisphere in Cycle 1 (August 2018 - July 2019), Cycle
3 (July 2020 - June 2021) and Cycle 5 (September 2022 - September 2023). We use
the observations from Cycle 1 and Cycle 3 to search for exoplanet systems that
show a single transit event in each year - which we call duotransits. The
periods of these planet candidates are typically in excess of 20 days, with the
lower limit determined by the duration of individual TESS observations. We find
85 duotransit candidates, which span a range of host star brightnesses between
8 < < 14, transit depths between 0.1 per cent and 1.8 per cent, and
transit durations between 2 and 10 hours with the upper limit determined by our
normalisation function. Of these candidates, 25 are already known, and 60 are
new. We present these candidates along with the status of photometric and
spectroscopic follow-up.Comment: 25 pages, 16 figures, submitted to Monthly Notices of the Royal
Astronomical Societ
The high-albedo, low polarization disk around HD 114082 harbouring a Jupiter-sized transiting planet
We present new optical and near-IR images of debris disk around the F-type
star HD 114082. We obtained direct imaging observations and analysed the TESS
photometric time series data of this target with a goal to search for planetary
companions and to characterise the morphology of the debris disk and the
scattering properties of dust particles. HD 114082 was observed with the
VLT/SPHERE instrument: the IRDIS camera in the K band together with the IFS in
the Y, J and H band using the ADI technique as well as IRDIS in the H band and
ZIMPOL in the I_PRIME band using the PDI technique. The scattered light images
were fitted with a 3D model for single scattering in an optically thin dust
disk. We performed aperture photometry in order to derive the scattering and
polarized phase functions, polarization fraction and spectral scattering albedo
for the dust particles in the disk. This method was also used to obtain the
reflectance spectrum of the disk to retrieve the disk color and study the dust
reflectivity in comparison to the debris disk HD 117214. We also performed the
modeling of the HD 114082 light curve measured by TESS using the models for
planet transit and stellar activity to put constraints on radius of the
detected planet and its orbit. The debris disk appears as an axisymmetric
debris belt with a radius of ~0.37 (35 au), inclination of ~83 and a
wide inner cavity. Dust particles in HD 114082 have a maximum polarization
fraction of ~17% and a high reflectivity which results in a spectral scattering
albedo of 0.65. The analysis of TESS photometric data reveals a transiting
planetary companion to HD 114082 with a radius of 1~ on an
orbit with a semi-major axis of au. Combining different data, we
reach deep sensitivity limits in terms of companion masses down to ~5 at 50 au, and ~10 at 30 au from the central star.Comment: 27 page
Two long-period transiting exoplanets on eccentric orbits: NGTS-20 b (TOI-5152 b) and TOI-5153 b
Long-period transiting planets provide the opportunity to better understand
the formation and evolution of planetary systems. Their atmospheric properties
remain largely unaltered by tidal or radiative effects of the host star, and
their orbital arrangement reflects a different, and less extreme, migrational
history compared to close-in objects. The sample of long-period exoplanets with
well determined masses and radii is still limited, but a growing number of
long-period objects reveal themselves in the TESS data. Our goal is to vet and
confirm single transit planet candidates detected in the TESS space-based
photometric data through spectroscopic and photometric follow up observations
with ground-based instruments. We use the Next Generation Transit Survey (NGTS)
to photometrically monitor the candidates in order to observe additional
transits. We report the discovery of two massive, warm Jupiter-size planets,
one orbiting the F8-type star TOI-5153 and the other orbiting the G1-type star
NGTS-20 (=TOI-5152). From our spectroscopic analysis, both stars are metal-rich
with a metallicity of 0.12 and 0.15, respectively. Follow-up radial velocity
observations were carried out with CORALIE, CHIRON, FEROS, and HARPS. TOI-5153
hosts a 20.33 day period planet with a planetary mass of 3.26 (+-0.18) Mj, a
radius of 1.06 (+-0.04) Rj , and an orbital eccentricity of 0.091 (+-0.026).
NGTS-20 b is a 2.98 (+-0.16) Mj planet with a radius of 1.07 (+-0.04) Rj on an
eccentric (0.432 +- 0.023) orbit with an orbital period of 54.19 days. Both
planets are metal-enriched and their heavy element content is in line with the
previously reported mass-metallicity relation for gas giants. Both warm
Jupiters orbit moderately bright host stars making these objects valuable
targets for follow-up studies of the planetary atmosphere and measurement of
the spin-orbit angle of the system.Comment: 17 pages, 13 figures, accepted to A&
Detection of the tidal deformation of WASP-103b at 3 σ with CHEOPS
Funding: A.C.C. and T.G.W. acknowledge support from STFC consolidated grant number ST/M001296/1.Context. Ultra-short period planets undergo strong tidal interactions with their host star which lead to planet deformation and orbital tidal decay. Aims: WASP-103b is the exoplanet with the highest expected deformation signature in its transit light curve and one of the shortest expected spiral-in times. Measuring the tidal deformation of the planet would allow us to estimate the second degree fluid Love number and gain insight into the planet's internal structure. Moreover, measuring the tidal decay timescale would allow us to estimate the stellar tidal quality factor, which is key to constraining stellar physics. Methods: We obtained 12 transit light curves of WASP-103b with the CHaracterising ExOplanet Satellite (CHEOPS) to estimate the tidal deformation and tidal decay of this extreme system. We modelled the high-precision CHEOPS transit light curves together with systematic instrumental noise using multi-dimensional Gaussian process regression informed by a set of instrumental parameters. To model the tidal deformation, we used a parametrisation model which allowed us to determine the second degree fluid Love number of the planet. We combined our light curves with previously observed transits of WASP-103b with the Hubble Space Telescope (HST) and Spitzer to increase the signal-to-noise of the light curve and better distinguish the minute signal expected from the planetary deformation. Results: We estimate the radial Love number of WASP-103b to be hf =1.59-0.53+0.45. This is the first time that the tidal deformation is directly detected (at 3 σ) from the transit light curve of an exoplanet. Combining the transit times derived from CHEOPS, HST, and Spitzer light curves with the other transit times available in the literature, we find no significant orbital period variation for WASP-103b. However, the data show a hint of an orbital period increase instead of a decrease, as is expected for tidal decay. This could be either due to a visual companion star if this star is bound, the Applegate effect, or a statistical artefact. Conclusions: The estimated Love number of WASP-103b is similar to Jupiter's. This will allow us to constrain the internal structure and composition of WASP-103b, which could provide clues on the inflation of hot Jupiters. Future observations with James Webb Space Telescope can better constrain the radial Love number of WASP-103b due to their high signal-to-noise and the smaller signature of limb darkening in the infrared. A longer time baseline is needed to constrain the tidal decay in this system. The transit light curves are only available at the CDS via anonymous ftpt o cdsarc.u-strasbg.fr(ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/657/A52.Publisher PDFPeer reviewe
Transit timing variations of AU Microscopii b and c
Funding: A.C.C. and T.W. acknowledge support from STFC consolidated grant number ST/M001296/1.Here we report large-amplitude transit timing variations (TTVs) for AU Microcopii b and c as detected in combined TESS (2018, 2020) and CHEOPS (2020, 2021) transit observations. AU Mic is a young planetary system with a debris disk and two transiting warm Neptunes. A TTV on the order of several minutes was previously reported for AU Mic b, which was suggested to be an outcome of mutual perturbations between the planets in the system. In 2021, we observed AU Mic b (five transits) and c (three transits) with the CHEOPS space telescope to follow-up the TTV of AU Mic b and possibly detect a TTV for AU Mic c. When analyzing TESS and CHEOPS 2020-2021 measurements together, we find that a prominent TTV emerges with a full span of >= 23 min between the two TTV extrema. Assuming that the period change results from a periodic process -such as mutual perturbations- we demonstrate that the times of transits in the summer of 2022 are expected to be 30-85 min later than predicted by the available linear ephemeris.Publisher PDFPeer reviewe
Dendritic Cells Transfected with scFv from Mab 7.B12 Mimicking Original Antigen gp43 Induces Protection against Experimental Paracoccidioidomycosis
Paracoccidioidomycosis (PCM), endemic in Latin America, is a progressive systemic mycosis caused by Paracoccidioides brasiliensis (P. brasiliensis), which primarily attacks lung tissue. Dendritic cells (DCs) are able to initiate a response in naïve T cells, and they also participate in Th-cell education. Furthermore, these cells have been used for therapy in several disease models. Here we transfected DCs with a plasmid (pMAC/PS-scFv) encoding a single chain variable fragment (scFv) of an anti-Id antibody that is capable of mimicking gp43, the main antigenic component of P. brasiliensis. First, Balb/c mice were immunized subcutaneously with pMAC/PS-scFv and, after seven days, scFv protein was presented to the regional lymph nodes cells. Moreover, we showed that the DCs transfected with scFv were capable of efficiently activating proliferation of total lymph node cells and inducing a decrease in lung infection. Therefore, our results suggested that the use of scFv-transfected DCs may be a promising therapy in the paracoccidioidomycosis (PCM) model
Refined parameters of the HD 22946 planetary system and the true orbital period of planet d
Multi-planet systems are important sources of information regarding the
evolution of planets. However, the long-period planets in these systems often
escape detection. HD 22946 is a bright star around which 3 transiting planets
were identified via TESS photometry, but the true orbital period of the
outermost planet d was unknown until now. We aim to use CHEOPS to uncover the
true orbital period of HD 22946d and to refine the orbital and planetary
properties of the system, especially the radii of the planets. We used the
available TESS photometry of HD 22946 and observed several transits of the
planets b, c, and d using CHEOPS. We identified 2 transits of planet d in the
TESS photometry, calculated the most probable period aliases based on these
data, and then scheduled CHEOPS observations. The photometric data were
supplemented with ESPRESSO radial velocity data. Finally, a combined model was
fitted to the entire dataset. We successfully determined the true orbital
period of the planet d to be 47.42489 0.00011 d, and derived precise
radii of the planets in the system, namely 1.362 0.040 R, 2.328
0.039 R, and 2.607 0.060 R for planets b, c, and
d, respectively. Due to the low number of radial velocities, we were only able
to determine 3 upper limits for these respective planet masses, which
are 13.71 M, 9.72 M, and 26.57 M. We estimated that
another 48 ESPRESSO radial velocities are needed to measure the predicted
masses of all planets in HD 22946. Planet c appears to be a promising target
for future atmospheric characterisation. We can also conclude that planet d, as
a warm sub-Neptune, is very interesting because there are only a few similar
confirmed exoplanets to date. Such objects are worth investigating in the near
future, for example in terms of their composition and internal structure
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