| 1. |
- Ahdida, C., et al.
(author)
-
Sensitivity of the SHiP experiment to dark photons decaying to a pair of charged particles
- 2021
-
In: European Physical Journal C. - : Springer Nature. - 1434-6044 .- 1434-6052. ; 81:5
-
Journal article (peer-reviewed)abstract
- Dark photons are hypothetical massive vector particles that could mix with ordinary photons. The simplest theoretical model is fully characterised by only two parameters: the mass of the dark photon m(gamma)D and its mixing parameter with the photon, epsilon. The sensitivity of the SHiP detector is reviewed for dark photons in the mass range between 0.002 and 10 GeV. Different productionmechanisms are simulated, with the dark photons decaying to pairs of visible fermions, including both leptons and quarks. Exclusion contours are presented and compared with those of past experiments. The SHiP detector is expected to have a unique sensitivity for m. D ranging between 0.8 and 3.3(-0.5)(+0.2) GeV, and epsilon(2) ranging between 10(-11) and 10(-17).
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| 2. |
- Ahdida, C., et al.
(author)
-
Sensitivity of the SHiP experiment to light dark matter
- 2021
-
In: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; :4
-
Journal article (peer-reviewed)abstract
- Dark matter is a well-established theoretical addition to the Standard Model supported by many observations in modern astrophysics and cosmology. In this context, the existence of weakly interacting massive particles represents an appealing solution to the observed thermal relic in the Universe. Indeed, a large experimental campaign is ongoing for the detection of such particles in the sub-GeV mass range. Adopting the benchmark scenario for light dark matter particles produced in the decay of a dark photon, with αD = 0.1 and mA′ = 3mχ, we study the potential of the SHiP experiment to detect such elusive particles through its Scattering and Neutrino detector (SND). In its 5-years run, corresponding to 2 · 1020 protons on target from the CERN SPS, we find that SHiP will improve the current limits in the mass range for the dark matter from about 1 MeV to 300 MeV. In particular, we show that SHiP will probe the thermal target for Majorana candidates in most of this mass window and even reach the Pseudo-Dirac thermal relic.
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| 3. |
- Ahdida, C., et al.
(author)
-
The magnet of the scattering and neutrino detector for the SHiP experiment at CERN
- 2020
-
In: Journal of Instrumentation. - 1748-0221. ; 15:01
-
Journal article (peer-reviewed)abstract
- The Search for Hidden Particles (SHiP) experiment proposal at CERN demands a dedicated dipole magnet for its scattering and neutrino detector. This requires a very large volume to be uniformly magnetized at B > 1.2 T, with constraints regarding the inner instrumented volume as well as the external region, where no massive structures are allowed and only an extremely low stray field is admitted. In this paper we report the main technical challenges and the relevant design options providing a comprehensive design for the magnet of the SHiP Scattering and Neutrino Detector.
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| 4. |
- Ahdida, C., et al.
(author)
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Track reconstruction and matching between emulsion and silicon pixel detectors for the SHiP-charm experiment
- 2022
-
In: Journal of Instrumentation. - : IOP Publishing. - 1748-0221. ; 17:3
-
Journal article (peer-reviewed)abstract
- In July 2018 an optimization run for the proposed charm cross section measurement for SHiP was performed at the CERN SPS. A heavy, moving target instrumented with nuclear emulsion films followed by a silicon pixel tracker was installed in front of the Goliath magnet at the H4 proton beam-line. Behind the magnet, scintillating-fibre, drift-tube and RPC detectors were placed. The purpose of this run was to validate the measurement's feasibility, to develop the required analysis tools and fine-tune the detector layout. In this paper, we present the track reconstruction in the pixel tracker and the track matching with the moving emulsion detector. The pixel detector performed as expected and it is shown that, after proper alignment, a vertex matching rate of 87% is achieved.
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| 5. |
- Ahdida, C., et al.
(author)
-
Fast simulation of muons produced at the SHiP experiment using Generative Adversarial Networks
- 2019
-
In: Journal of Instrumentation. - : IOP PUBLISHING LTD. - 1748-0221. ; 14
-
Journal article (peer-reviewed)abstract
- This paper presents a fast approach to simulating muons produced in interactions of the SPS proton beams with the target of the SHiP experiment. The SHIP experiment will be able to search for new long-lived particles produced in a 400 GeV/c SPS proton beam dump and which travel distances between fifty metres and tens of kilometers. The SHiP detector needs to operate under ultra-low background conditions and requires large simulated samples of muon induced background processes. Through the use of Generative Adversarial Networks it is possible to emulate the simulation of the interaction of 400 GeV/c proton beams with the SHiP target, an otherwise computationally intensive process. For the simulation requirements of the SHiP experiment, generative networks are capable of approximating the full simulation of the dense fixed target, offering a speed increase by a factor of O(10(6)). To evaluate the performance of such an approach, comparisons of the distributions of reconstructed muon momenta in SHiP's spectrometer between samples using the full simulation and samples produced through generative models are presented. The methods discussed in this paper can be generalised and applied to modelling any non-discrete multi-dimensional distribution.
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| 6. |
- Ahdida, C., et al.
(author)
-
Measurement of the muon flux from 400 GeV/c protons interacting in a thick molybdenum/tungsten target
- 2020
-
In: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 80:3
-
Journal article (peer-reviewed)abstract
- The SHiP experiment is proposed to search for very weakly interacting particles beyond the Standard Model which are produced in a 400 GeV/c proton beam dump at the CERN SPS. About 1011muons per spill will be produced in the dump. To design the experiment such that the muon-induced background is minimized, a precise knowledge of the muon spectrum is required. To validate the muon flux generated by our Pythia and GEANT4 based Monte Carlo simulation (FairShip), we have measured the muon flux emanating from a SHiP-like target at the SPS. This target, consisting of 13 interaction lengths of slabs of molybdenum and tungsten, followed by a 2.4 m iron hadron absorber was placed in the H4 400 GeV/c proton beam line. To identify muons and to measure the momentum spectrum, a spectrometer instrumented with drift tubes and a muon tagger were used. During a 3-week period a dataset for analysis corresponding to (3.27 +/- 0.07)x1011protons on target was recorded. This amounts to approximatively 1% of a SHiP spill.
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| 7. |
- Ahdida, C., et al.
(author)
-
Sensitivity of the SHiP experiment to Heavy Neutral Leptons
- 2019
-
In: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; :4
-
Journal article (peer-reviewed)abstract
- Heavy Neutral Leptons (HNLs) are hypothetical particles predicted by many extensions of the Standard Model. These particles can, among other things, explain the origin of neutrino masses, generate the observed matter-antimatter asymmetry in the Universe and provide a dark matter candidate. The SHiP experiment will be able to search for HNLs produced in decays of heavy mesons and travelling distances ranging between O(50 m) and tens of kilometers before decaying. We present the sensitivity of the SHiP experiment to a number of HNL's benchmark models and provide a way to calculate the SHiP's sensitivity to HNLs for arbitrary patterns of flavour mixings. The corresponding tools and data files are also made publicly available.
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| 8. |
- Ahdida, C., et al.
(author)
-
The experimental facility for the Search for Hidden Particles at the CERN SPS
- 2019
-
In: Journal of Instrumentation. - : Institute of Physics Publishing (IOPP). - 1748-0221. ; 14
-
Journal article (peer-reviewed)abstract
- The Search for Hidden Particles (SHiP) Collaboration has shown that the CERN SPS accelerator with its 400 GeV/c proton beam offers a unique opportunity to explore the Hidden Sector [1-3]. The proposed experiment is an intensity frontier experiment which is capable of searching for hidden particles through both visible decays and through scattering signatures from recoil of electrons or nuclei. The high-intensity experimental facility developed by the SHiP Collaboration is based on a number of key features and developments which provide the possibility of probing a large part of the parameter space for a wide range of models with light long-lived super-weakly interacting particles with masses up to O(10) GeV/c(2) in an environment of extremely clean background conditions. This paper describes the proposal for the experimental facility together with the most important feasibility studies. The paper focuses on the challenging new ideas behind the beam extraction and beam delivery, the proton beam dump, and the suppression of beam-induced background.
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| 9. |
- Ahdida, C., et al.
(author)
-
The SHiP experiment at the proposed CERN SPS Beam Dump Facility
- 2022
-
In: European Physical Journal C. - : Springer Nature. - 1434-6044 .- 1434-6052. ; 82:5
-
Journal article (peer-reviewed)abstract
- The Search for Hidden Particles (SHiP) Collaboration has proposed a general-purpose experimental facility operating in beam-dump mode at the CERN SPS accelerator to search for light, feebly interacting particles. In the baseline configuration, the SHiP experiment incorporates two complementary detectors. The upstream detector is designed for recoil signatures of light dark matter (LDM) scattering and for neutrino physics, in particular with tau neutrinos. It consists of a spectrometer magnet housing a layered detector system with high-density LDM/neutrino target plates, emulsion-film technology and electronic high-precision tracking. The total detector target mass amounts to about eight tonnes. The downstream detector system aims at measuring visible decays of feebly interacting particles to both fully reconstructed final states and to partially reconstructed final states with neutrinos, in a nearly background-free environment. The detector consists of a 50m\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathrm { \,m}$$\end{document} long decay volume under vacuum followed by a spectrometer and particle identification system with a rectangular acceptance of 5 m in width and 10 m in height. Using the high-intensity beam of 400GeV\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\,\mathrm {GeV}$$\end{document} protons, the experiment aims at profiting from the 4x1019\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$4\times 10<^>{19}$$\end{document} protons per year that are currently unexploited at the SPS, over a period of 5-10 years. This allows probing dark photons, dark scalars and pseudo-scalars, and heavy neutral leptons with GeV-scale masses in the direct searches at sensitivities that largely exceed those of existing and projected experiments. The sensitivity to light dark matter through scattering reaches well below the dark matter relic density limits in the range from a few MeV/c2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathrm {\,MeV\!/}c<^>2}$$\end{document} up to 100 MeV-scale masses, and it will be possible to study tau neutrino interactions with unprecedented statistics. This paper describes the SHiP experiment baseline setup and the detector systems, together with performance results from prototypes in test beams, as it was prepared for the 2020 Update of the European Strategy for Particle Physics. The expected detector performance from simulation is summarised at the end.
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| 10. |
- Milstead, David A., et al.
(author)
-
The active muon shield in the SHiP experiment
- 2017
-
In: Journal of Instrumentation. - 1748-0221. ; 12
-
Journal article (peer-reviewed)abstract
- The SHiP experiment is designed to search for very weakly interacting particles beyond the Standard Model which are produced in a 400 GeV/c proton beam dump at the CERN SPS. An essential task for the experiment is to keep the Standard Model background level to less than 0.1 event after 2 x 10(20) protons on target. In the beam dump, around 10(11) muons will be produced per second. The muon rate in the spectrometer has to be reduced by at least four orders of magnitude to avoid muon-induced combinatorial background. A novel active muon shield is used to magnetically deflect the muons out of the acceptance of the spectrometer. This paper describes the basic principle of such a shield, its optimization and its performance.
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| 11. |
- Hoeijmakers, H. J., et al.
(author)
-
Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) : IV. A spectral inventory of atoms and molecules in the high-resolution transmission spectrum of WASP-121 b
- 2020
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 641
-
Journal article (peer-reviewed)abstract
- Context. WASP-121 b is a hot Jupiter that was recently found to possess rich emission (day side) and transmission (limb) spectra, suggestive of the presence of a multitude of chemical species in the atmosphere. Aims. We survey the transmission spectrum of WASP-121 b for line-absorption by metals and molecules at high spectral resolution and elaborate on existing interpretations of the optical transmission spectrum observed with the Hubble Space Telescope (HST). Methods. We applied the cross-correlation technique and direct differential spectroscopy to search for sodium and other neutral and ionised atoms, TiO, VO, and SH in high-resolution transit spectra obtained with the HARPS spectrograph. We injected models assuming chemical and hydrostatic equilibrium with a varying temperature and composition to enable model comparison, and employed two bootstrap methods to test the robustness of our detections. Results. We detect neutral Mg, Na, Ca, Cr, Fe, Ni, and V, which we predict exists in equilibrium with a significant quantity of VO, supporting earlier observations by HST/WFC3. Non-detections of Ti and TiO support the hypothesis that Ti is depleted via a cold-trap mechanism, as has been proposed in the literature. Atomic line depths are under-predicted by hydrostatic models by a factor of 1.5 to 8, confirming recent findings that the atmosphere is extended. We predict the existence of significant concentrations of gas-phase TiO2, VO2, and TiS, which could be important absorbers at optical and near-IR wavelengths in hot Jupiter atmospheres. However, accurate line-list data are not currently available for them. We find no evidence for absorption by SH and find that inflated atomic lines can plausibly explain the slope of the transmission spectrum observed in the near-ultraviolet with HST. The Na I D lines are significantly broadened (FWHM ∼50 to 70 km s-1) and show a difference in their respective depths of ~15 scale heights, which is not expected from isothermal hydrostatic theory. If this asymmetry is of astrophysical origin, it may indicate that Na I forms an optically thin envelope, reminiscent of the Na I cloud surrounding Jupiter, or that it is hydrodynamically outflowing.
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| 12. |
- Leleu, A., et al.
(author)
-
Six transiting planets and a chain of Laplace resonances in TOI-178
- 2021
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 649
-
Journal article (peer-reviewed)abstract
- Determining the architecture of multi-planetary systems is one of the cornerstones of understanding planet formation and evolution. Resonant systems are especially important as the fragility of their orbital configuration ensures that no significant scattering or collisional event has taken place since the earliest formation phase when the parent protoplanetary disc was still present. In this context, TOI-178 has been the subject of particular attention since the first TESS observations hinted at the possible presence of a near 2:3:3 resonant chain. Here we report the results of observations from CHEOPS, ESPRESSO, NGTS, and SPECULOOS with the aim of deciphering the peculiar orbital architecture of the system. We show that TOI-178 harbours at least six planets in the super-Earth to mini-Neptune regimes, with radii ranging from 1.152 to 2.87 Earth radii and periods of 1.91, 3.24, 6.56, 9.96, 15.23, and 20.71 days. All planets but the innermost one form a 2:4:6:9:12 chain of Laplace resonances, and the planetary densities show important variations from planet to planet, jumping from 1.02 to 0.177 times the Earth's density between planets c and d. Using Bayesian interior structure retrieval models, we show that the amount of gas in the planets does not vary in a monotonous way, contrary to what one would expect from simple formation and evolution models and unlike other known systems in a chain of Laplace resonances. The brightness of TOI-178 (H = 8.76 mag, J = 9.37 mag, V = 11.95 mag) allows for a precise characterisation of its orbital architecture as well as of the physical nature of the six presently known transiting planets it harbours. The peculiar orbital configuration and the diversity in average density among the planets in the system will enable the study of interior planetary structures and atmospheric evolution, providing important clues on the formation of super-Earths and mini-Neptunes. -0.070 -0.13 -0.23 -0.061 +0.073 +0.14 +0.28 +0.055
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| 13. |
- Zenteno, A., et al.
(author)
-
A joint SZ-X-ray-optical analysis of the dynamical state of 288 massive galaxy clusters
- 2020
-
In: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 495:1, s. 705-725
-
Journal article (peer-reviewed)abstract
- We use imaging from the first three years of the Dark Energy Survey to characterize the dynamical state of 288 galaxy clusters at 0.1 less than or similar to z less than or similar to 0.9 detected in the South Pole Telescope (SPT) Sunyaev-Zeldovich (SZ) effect survey (SPT-SZ). We examine spatial offsets between the position of the brightest cluster galaxy (BCG) and the centre of the gas distribution as traced by the SPT-SZ centroid and by the X-ray centroid/peak position from Chandra and XMM data. We show that the radial distribution of offsets provides no evidence that SPT SZ-selected cluster samples include a higher fraction of mergers than X-ray-selected cluster samples. We use the offsets to classify the dynamical state of the clusters, selecting the 43 most disturbed clusters, with half of those at z greater than or similar to 0.5, a region seldom explored previously. We find that Schechter function fits to the galaxy population in disturbed clusters and relaxed clusters differ at z > 0.55 but not at lower redshifts. Disturbed clusters at z > 0.55 have steeper faint-end slopes and brighter characteristic magnitudes. Within the same redshift range, we find that the BCGs in relaxed clusters tend to be brighter than the BCGs in disturbed samples, while in agreement in the lower redshift bin. Possible explanations includes a higher merger rate, and a more efficient dynamical friction at high redshift. The red-sequence population is less affected by the cluster dynamical state than the general galaxy population.
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| 14. |
- Barragan, O., et al.
(author)
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The young HD 73583 (TOI-560) planetary system: two 10-M-circle plus mini-Neptunes transiting a 500-Myr-old, bright, and active K dwarf
- 2022
-
In: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 514:2, s. 1606-1627
-
Journal article (peer-reviewed)abstract
- We present the discovery and characterization of two transiting planets observed by TESS in the light curves of the young and bright (V = 9.67) star HD73583 (TOI-560). We perform an intensive spectroscopic and photometric space- and ground-based follow-up in order to confirm and characterize the system. We found that HD73583 is a young (similar to 500 Myr) active star with a rotational period of 12.08 +/- 0.11 d, and a mass and radius of 0.73 +/- 0.02 M-circle dot and 0.65 +/- 0.02 R-circle dot, respectively. HD 73583 b (P-b = 6.3980420(-0.0000062)(+0.0000067 )d) has a mass and radius of 10.2(-3.1)(+3.4) M-circle plus and 2.79 +/- 0.10 R-circle plus, respectively, which gives a density of 2.58(-0.81)(+0.95) g cm(-3). HD 73583 c (P-c = 18.87974(-0.00074)(+0.00086) d) has a mass and radius of 9.7(-1.7)(+1.8) M-circle plus and 2.39(-0.09)(+0.10) R-circle plus, respectively, which translates to a density of 3.88(-0.80)(+0.91) g cm(-3). Both planets are consistent with worlds made of a solid core surrounded by a volatile envelope. Because of their youth and host star brightness, they both are excellent candidates to perform transmission spectroscopy studies. We expect ongoing atmospheric mass-loss for both planets caused by stellar irradiation. We estimate that the detection of evaporating signatures on H and He would be challenging, but doable with present and future instruments.
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| 15. |
- Esposito, M., et al.
(author)
-
HD 219666 b: a hot-Neptune from TESS Sector 1
- 2019
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 623:623
-
Journal article (peer-reviewed)abstract
- We report on the confirmation and mass determination of a transiting planet orbiting the old and inactive G7 dwarf star HD219666 (M-star = 0.92 +/- 0.03 M-circle dot, R-star = 1.03 +/- 0.03 R-circle dot, tau(star) = 10 +/- 2 Gyr). With a mass of M-b = 16.6 +/- 1.3 M-circle plus, a radius of R-b = 4.71 +/- 0.17 R-circle plus, and an orbital period of P-orb similar or equal to 6 days, HD219666 b is a new member of a rare class of exoplanets: the hot-Neptunes. The Transiting Exoplanet Survey Satellite (TESS) observed HD219666 (also known as TOI-118) in its Sector 1 and the light curve shows four transit-like events, equally spaced in time. We confirmed the planetary nature of the candidate by gathering precise radial-velocity measurements with the High Accuracy Radial velocity Planet Searcher (HARPS) at ESO 3.6 m. We used the co-added HARPS spectrum to derive the host star fundamental parameters (T-eff = 5527 +/- 65 K, log g(star) = 4.40 +/- 0.11 (cgs), [Fe/H] = 0.04 +/- 0.04 dex, log R-HK' = -5.07 +/- 0.03), as well as the abundances of many volatile and refractory elements. The host star brightness (V = 9.9) makes it suitable for further characterisation by means of in-transit spectroscopy. The determination of the planet orbital obliquity, along with the atmospheric metal-to-hydrogen content and thermal structure could provide us with important clues on the formation mechanisms of this class of objects.
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| 16. |
- Hoyer, S., et al.
(author)
-
TOI-220b: a warm sub-Neptune discovered by TESS
- 2021
-
In: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 505:3, s. 3361-3379
-
Journal article (peer-reviewed)abstract
- In this paper, we report the discovery of TOI-220b, a new sub-Neptune detected by the Transiting Exoplanet Survey Satellite (TESS) and confirmed by radial velocity follow-up observations with the HARPS spectrograph. Based on the combined analysis of TESS transit photometry and high precision radial velocity measurements, we estimate a planetary mass of 13.8 +/- 1.0M(circle plus) and radius of 3.03 +/- 0.15R(circle plus), implying a bulk density of 2.73 +/- 0.47. TOI-220b orbits a relative bright (V=10.4) and old (10.1 +/- 1.4Gyr) K dwarf star with a period of similar to 10.69d. Thus, TOI-220b is a new warm sub-Neptune with very precise mass and radius determinations. A Bayesian analysis of the TOI-220b internal structure indicates that due to the strong irradiation it receives, the low density of this planet could be explained with a steam atmosphere in radiative-convective equilibrium and a supercritical water layer on top of a differentiated interior made of a silicate mantle and a small iron core.
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| 17. |
- Nielsen, L. D., et al.
(author)
-
Mass determinations of the three mini-Neptunes transiting TOI-125
- 2020
-
In: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 492:4, s. 5399-5412
-
Journal article (peer-reviewed)abstract
- The Transiting Exoplanet Survey Satellite, TESS, is currently carrying out an all-sky search for small planets transiting bright stars. In the first year of the TESS survey, a steady progress was made in achieving the mission's primary science goal of establishing bulk densities for 50 planets smaller than Neptune. During that year, the TESS's observations were focused on the southern ecliptic hemisphere, resulting in the discovery of three mini-Neptunes orbiting the star T01-125, a V = 11,0 KO dwarf. We present intensive HARPS radial velocity observations, yielding precise mass measurements for TO1-125b, TOI-125c, and TOI-125d. TOI-125b has an orbital period of 4,65 d, a radius of 2,726 + 0,075 RE, a mass of 9,50 0,88 ME, and is near the 2:1 mean motion resonance with TOI-125c at 9.15 d. TOI-125c has a similar radius of 2,759 0.10 RE and a mass of 6,63 + 0,99 ME, being the puffiest of the three planets. T01-125d has an orbital period of 19,98 d and a radius of 2.93 + 0,17 RE and mass 13,6 1,2 ME, For T01-125b and d, we find unusual high eccentricities of 0.19 0.04 and 0.17+(c):(!,(, respectively. Our analysis also provides upper mass limits for the two low-SNR planet candidates in the system; for T01-125.04 (Rp = 1.36 RE, P = 0.53 d), we find a 2a upper mass limit of 1.6 ME, whereas T01-125.05 (RP = 4.2-'2E44 RE, P = 13.28 d) is unlikely a viable planet candidate with an upper mass limit of 2.7 ME. We discuss the internal structure of the three confirmed planets, as well as dynamical stability and system architecture for this intriguing exoplanet system.
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| 18. |
- Seidel, J. V., et al.
(author)
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Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) : V. Detection of sodium on the bloated super-Neptune WASP-166b
- 2020
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 641
-
Journal article (peer-reviewed)abstract
- Planet formation processes or evolution mechanisms are surmised to be at the origin of the hot Neptune desert. Studying exoplanets currently living within or at the edge of this desert could allow disentangling the respective roles of formation and evolution. We present the High Accuracy Radial velocity Planet Searcher (HARPS) transmission spectrum of the bloated super-Neptune WASP-166b, located at the outer rim of the Neptune desert. Neutral sodium is detected at the 3.4σ level (0.455†±â€ 0.135%), with a tentative indication of line broadening, which could be caused by winds blowing sodium farther into space, a possible manifestation of the bloated character of these highly irradiated worlds. We put this detection into context with previous work claiming a non-detection of sodium in the same observations and show that the high noise in the trace of the discarded stellar sodium lines was responsible for the non-detection. We highlight the impact of this low signal-to-noise ratio remnant on detections for exoplanets similar to WASP-166b.
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| 19. |
- Bento, J., et al.
(author)
-
HATS-22b, HATS-23b and HATS-24b : three new transiting super-Jupiters from the HATSouth project
- 2017
-
In: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 468:1, s. 835-848
-
Journal article (peer-reviewed)abstract
- We report the discovery of three moderately high-mass transiting hot Jupiters from the HATSouth survey: HATS-22b, HATS-23b and HATS-24b. These planets add to the number of known planets in the similar to 2MJ regime. HATS-22b is a 2.74 +/- 0.11MJ mass and 0.953(-0.029)(+0.048) R-J radius planet orbiting a V = 13.455 +/- 0.040 sub-solar mass (M-* = 0.759 +/- 0.019M(circle dot); R-* = 0.759 +/- 0.019 R-circle dot) K-dwarf host star on an eccentric (e = 0.079 +/- 0.026) orbit. This planet's high planet-to-stellar mass ratio is further evidence that migration mechanisms for hot Jupiters may rely on exciting orbital eccentricities that bring the planets closer to their parent stars followed by tidal circularization. HATS-23b is a 1.478 +/- 0.080M(J) mass and 1.69 +/- 0.24 R-J radius planet on a grazing orbit around a V = 13.901 +/- 0.010 G-dwarf with properties very similar to those of the Sun (M* = 1.115 +/- 0.054; R-* = 1.145 +/- 0.070). HATS24b orbits a moderately bright V = 12.830 +/- 0.010 F-dwarf star (M-* = 1.218 +/- 0.036M circle dot; R-* = 1.194(-0.041)(+0.066) R circle dot). This planet has a mass of 2.39+0.21 -0.12MJ and an inflated radius of 1.516(-0.065)(+0.085) R-J.
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| 20. |
- Brahm, R., et al.
(author)
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HATS-43b, HATS-44b, HATS-45b, and HATS-46b : Four Short-period Transiting Giant Planets in the Neptune-Jupiter Mass Range
- 2018
-
In: Astronomical Journal. - : American Astronomical Society. - 0004-6256 .- 1538-3881. ; 155:3
-
Journal article (peer-reviewed)abstract
- We report the discovery of four short-period extrasolar planets transiting moderately bright stars from photometric measurements of the HATSouth network coupled to additional spectroscopic and photometric follow-up observations. While the planet masses range from 0.26 to 0.90 M-J, the radii are all approximately a Jupiter radii, resulting in a wide range of bulk densities. The orbital period of the planets ranges from 2.7 days to 4.7 days, with HATS-43b having an orbit that appears to be marginally non-circular (e = 0.173 +/- 0.089). HATS-44 is notable for having a high metallicity ([Fe/H]= 0.320 +/- 0.071). The host stars spectral types range from late F to early K, and all of them are moderately bright (13.3 < V < 14.4), allowing the execution of future detailed follow-up observations. HATS-43b and HATS-46b, with expected transmission signals of 2350 ppm and 1500 ppm, respectively, are particularly well suited targets for atmospheric characterization via transmission spectroscopy.
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| 21. |
- Carter, Aarynn L., et al.
(author)
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A benchmark JWST near-infrared spectrum for the exoplanet WASP-39 b
- 2024
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In: Nature Astronomy. - 2397-3366. ; In Press
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Journal article (peer-reviewed)abstract
- A combined analysis of datasets across four JWST instrument modes provides a benchmark transmission spectrum for the Saturn-mass WASP-39 b. The broad wavelength range and high resolution constrain orbital and stellar parameters to below 1%.
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| 22. |
- de Val-Borro, M., et al.
(author)
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HATS-31B THROUGH HATS-35B : FIVE TRANSITING HOT JUPITERS DISCOVERED BY THE HATSOUTH SURVEY
- 2016
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In: Astronomical Journal. - : American Astronomical Society. - 0004-6256 .- 1538-3881. ; 152:6
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Journal article (peer-reviewed)abstract
- We report the discovery of five new transiting hot-Jupiter planets discovered by the HATSouth survey, HATS-31b through HATS-35b. These planets orbit moderately bright stars with V magnitudes within the range of 11.9-14.4 mag while the planets span a range of masses of. 0.88-1.22 M-J. and have somewhat inflated radii between 1.23 and 1.64 R-J. These planets can be classified as typical hot Jupiters, with HATS-31b and HATS-35b being moderately inflated gas giant planets with radii of 1.64 +/- 0.22 R-J and 1.464(-0.044)(+0.069) R-J, respectively, that can be used to constrain inflation mechanisms. All five systems present a higher Bayesian evidence for a fixed-circular-orbit model than for an eccentric orbit. The orbital periods range from 1.8209993 +/- 0.0000016 day for HATS-35b) to 3.377960 +/- 0.000012 day for HATS-31b. Additionally, HATS-35b orbits a relatively young F star with an age of 2.13 +/- 0.51 Gyr. We discuss the analysis to derive the properties of these systems and compare them in the context of the sample of well-characterized transiting hot Jupiters known to date.
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| 23. |
- Henning, Th., et al.
(author)
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HATS-50b through HATS-53b : Four Transiting Hot Jupiters Orbiting G-type Stars Discovered by the HATSouth Survey
- 2018
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In: Astronomical Journal. - : American Astronomical Society. - 0004-6256 .- 1538-3881. ; 155:2
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Journal article (peer-reviewed)abstract
- We report the discovery of four close-in transiting exoplanets (HATS-50b through HATS-53b), discovered using the HATSouth three-continent network of homogeneous and automated telescopes. These new exoplanets belong to the class of hot Jupiters and orbit G-type dwarf stars, with brightness in the range V = 12.5-14.0 mag. While HATS-53 has many physical characteristics similar to the Sun, the other three stars appear to be metal-rich ([Fe/H]= 0.2-0.3), larger, and more massive. Three of the new exoplanets, namely HATS-50b, HATS-51b, and HATS-53b, have low density (HATS-50b: 0.39 +/- 0.10 M-J, 1.130 +/- 0.075 R-J; HATS-51b: 0.768 +/- 0.045 M-J, 1.41 +/- 0.19 R-J; HATS-53b: 0.595 +/- 0.089 M-J, 1.340 +/- 0.056 R-J) and similar orbital periods (3.8297 days, 3.3489 days, 3.8538 days, respectively). Instead, HATS-52b is more dense (mass 2.24. +/- 0.15 M-J and radius 1.382 +/- 0.086 R-J) and has a shorter orbital period (1.3667 days). It also receives an intensive radiation from its parent star and, consequently, presents a high equilibrium temperature (T-eq = 1834 +/- 73 K). HATS-50 shows a marginal additional transit feature consistent with an ultra-short-period hot super Neptune (upper mass limit 0.16 M-J), which will be able to be confirmed with TESS photometry.
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| 24. |
- Martell, S., et al.
(author)
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The GALAH survey : Scientific motivation
- 2015
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In: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 449:3
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Journal article (peer-reviewed)abstract
- The Galactic Archaeology with HERMES (GALAH) survey is a large high-resolution spectroscopic survey using the newly commissioned High Efficiency and Resolution Multi-Element Spectrograph (HERMES) on the Anglo-Australian Telescope. The HERMES spectrograph provides high-resolution (R ~ 28 000) spectra in four passbands for 392 stars simultaneously over a 2 deg field of view. The goal of the survey is to unravel the formation and evolutionary history of the Milky Way, using fossil remnants of ancient star formation events which have been disrupted and are now dispersed throughout the Galaxy. Chemical tagging seeks to identify such dispersed remnants solely from their common and unique chemical signatures; these groups are unidentifiable from their spatial, photometric or kinematic properties. To carry out chemical tagging, the GALAH survey will acquire spectra for a million stars down to V ~ 14. The HERMES spectra of FGK stars contain absorption lines from 29 elements including light proton-capture elements, α-elements, odd-Z elements, iron-peak elements and n-capture elements from the light and heavy s-process and the r-process. This paper describes the motivation and planned execution of the GALAH survey, and presents some results on the first-light performance of HERMES.
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| 25. |
- Osborn, A., et al.
(author)
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TOI-332 b: a super dense Neptune found deep within the Neptunian desert
- 2023
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In: Monthly Notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 526:1, s. 548-566
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Journal article (peer-reviewed)abstract
- To date, thousands of planets have been discovered, but there are regions of the orbital parameter space that are still bare. An example is the short period and intermediate mass/radius space known as the 'Neptunian desert', where planets should be easy to find but discoveries remain few. This suggests unusual formation and evolution processes are responsible for the planets residing here. We present the discovery of TOI-332 b, a planet with an ultra-short period of 0.78 d that sits firmly within the desert. It orbits a K0 dwarf with an effective temperature of 5251 ± 71 K. TOI-332 b has a radius of R, smaller than that of Neptune, but an unusually large mass of 57.2 ± 1.6 M. It has one of the highest densities of any Neptune-sized planet discovered thus far at g cm-3. A 4-layer internal structure model indicates it likely has a negligible hydrogen-helium envelope, something only found for a small handful of planets this massive, and so TOI-332 b presents an interesting challenge to planetary formation theories. We find that photoevaporation cannot account for the mass-loss required to strip this planet of the Jupiter-like envelope it would have been expected to accrete. We need to look towards other scenarios, such as high-eccentricity migration, giant impacts, or gap opening in the protoplanetary disc, to try and explain this unusual discovery.
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