63 research outputs found
Research and development of ground-based transiting extrasolar planet projects
The search for exoplanets has gone from the realm of speculation to being
one of the most prolific topics of modern astronomy in the space of just 20 years.
In particular, the geometric alignment of transiting exoplanets provides the added
opportunity to measure a host of properties of these systems, including studies of
planetary atmospheres.
The vast majority of known transiting exoplanets to date were found using
dedicated ground-based surveys such as the SuperWASP project. Such enterprises
comprise of multiple small telescopes designed to perform high-precision photometry
over a wide field of view and rely on efficiently compensating for several noise
contributions. An analysis of the sources of noise in the SuperWASP light curves
was performed, focussing on systematic e↵ects fixed in detector space. A study of
a set of detector maps produced from the average of the fractional residuals of the
light curves in CCD coordinates has revealed that the current flat-fielding strategy
is introducing a component of red noise into the light curves due to the wavelengthdependent
nature of the CCDs. The possibility of using such maps as a basis for an
additional decorrelation step in the software pipeline is discussed.
The next phase in planetary discoveries from ground-based surveys consists
of the search for smaller planets and those in longer orbits around their host stars.
This process involves an observing strategy that focuses on intensive coverage of
particular locations of the sky. We develop simulation software to aid the choice of
observed fields for the SuperWASP and Next Generation Transit Survey (NGTS)
projects in order to maximise the chances of finding planets at those locations.
Moreover, this simulation can be used for comparative studies of the planet finding
probability for several design choices and has been used to justify the necessity to
commission the NGTS instrument at ESO’s Paranal Observatory in order to benefit
from one of the World’s premier sites.
The increasing number of known transiting planets has triggered a new phase
of exoplanet exploration, in which the properties of the atmospheres of these planets
are being explored using techniques such as transmission spectroscopy. This process
consists of measuring an enhanced transit depth at particular wavelengths due to
the presence of opacity sources in the atmospheres of exoplanets. We use the multiband
photometer ULTRACAM to attempt a similar measurement via the technique
of transmission photometry for the highly inflated planets WASP-15b and WASP-
17b. The data are found to be dominated by systematic errors and a detailed study
of the possible sources is performed
Precision single mode fibre integral field spectroscopy with the RHEA spectrograph
The RHEA Spectrograph is a single-mode echelle spectrograph designed to be a replicable and cost effective method of undertaking precision radial velocity measurements. Two versions of RHEA currently exist, one located at the Australian National University in Canberra, Australia (450 - 600nm wavelength range), and another located at the Subaru Telescope in Hawaii, USA (600 - 800 nm wavelength range). Both instruments have a novel fibre feed consisting of an integral field unit injecting light into a 2D grid of single mode fibres. This grid of fibres is then reformatted into a 1D array at the input of the spectrograph (consisting of the science fibres and a reference fibre capable of receiving a white-light or xenon reference source for simultaneous calibration). The use of single mode fibres frees RHEA from the issue of modal noise and significantly reduces the size of the optics used. In addition to increasing the overall light throughput of the system, the integral field unit allows for cutting edge science goals to be achieved when operating behind the 8.2 m Subaru Telescope and the SCExAO adaptive optics system. These include, but are not limited to: resolved stellar photospheres; resolved protoplanetary disk structures; resolved Mira shocks, dust and winds; and sub-arcsecond companions. We present details and results of early tests of RHEA@Subaru and progress towards the stated science goals
Collaborative virtual community to share class plans for STEAM education
This research presents an international community of practice for teachers using the VISIR remote lab. Throughout the research, it was necessary to study about communities of practice and their potential use in remote laboratories; identify practices with collaborative potential in the institutions and with the participating teachers; develop the necessary technological environment to support the proposed community of practice; validate the proposal with four institutions (four countries - Brazil, Portugal, Spain and Argentina) to evaluate the proposed model. The motivation for developing this research came from the history of the Remote Experimentation Laboratory (REXLAB) with the project VISIR+: Educational Modules for Electric and Electronic Circuits Theory and Practice following an Enquiry based Teaching and Learning Methodology supported by VISIR+”. The VISIR + project is an international cooperation project with the participation of 21 Ibero-American partner institutions between October 2015 and April 2018. The platform, called Labs4STEAM, was developed using Dokuwiki, an open source wiki software that contains a large number of plugins. From the data collection it was possible to receive a mostly positive feedback, but several improvement opportunities were pointed out, which will be performed soon. Thus, from the developed platform one can plan future work, taking into account the results obtained and experience and partnerships with the VISIR + project.The research was financed by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), the Erasmus+ programme through grant 561735-EPP-1-2015-1-PT-EPPKA2-CBHE-JP, and also by FCT through grant EQU/04730/2020.info:eu-repo/semantics/publishedVersio
NGTS: a robotic transit survey to detect Neptune and Super-Earth mass planets
NGTS is a new ground-based transit survey aimed at detecting sub-Neptune sized exoplanets around bright stars. The instrument will be installed at the ESO Paranal observatory in order to benefit from the excellent observing conditions and follow-up synergy with the VLT and E-ELT. It will be a robotic facility composed of 12, 200 mm telescopes equipped with 2Kx2K NIR sensitive detectors. It is built on the legacy of the WASP experience
Kelt-17B: A Hot-Jupiter Transiting an A-Star in a misaligned orbit detected with Doppler Tomography
We present the discovery of a hot Jupiter transiting the V = 9.23 mag main-sequence A-star KELT-17 (BD+14 1881). KELT-17b is a , hot-Jupiter in a 3.08-day period orbit misaligned at −115fdg9 ± 4fdg1 to the rotation axis of the star. The planet is confirmed via both the detection of the radial velocity orbit, and the Doppler tomographic detection of the shadow of the planet during two transits. The nature of the spin–orbit misaligned transit geometry allows us to place a constraint on the level of differential rotation in the host star; we find that KELT-17 is consistent with both rigid-body rotation and solar differential rotation rates ( at significance). KELT-17 is only the fourth A-star with a confirmed transiting planet, and with a mass of , an effective temperature of 7454 ± 49 K, and a projected rotational velocity of it is among the most massive, hottest, and most rapidly rotating of known planet hosts
WASP-34b: A near-grazing transiting sub-Jupiter-mass exoplanet in a hierarchical triple system
We report the discovery of WASP-34b, a sub-Jupiter-mass exoplanet transiting its 10.4-magnitude solar-type host star (1SWASP J110135.89-235138.4; TYC 6636-540-1) every 4.3177 days in a slightly eccentric orbit (e = 0.038±0.012). We find a planetary mass of 0.59±0.01 M Jup and radius of 1.22-0.08 +0.11 R Jup. There is a linear trend in the radial velocities of 55±4 m s-1 y-1 indicating the presence of a long-period third body in the system with a mass ≥0.45 MJup at a distance of ≥1.2 AU from the host star. This third-body is either a low-mass star, a white dwarf, or another planet. The transit depth ((RP/R*) 2 = 0.0126) and high impact parameter (b = 0.90) suggest that this could be the first known transiting exoplanet expected to undergo grazing transits, but with a confidence of only ~80
Simultaneous infrared and optical observations of the transiting debris cloud around WD 1145+017
We present multiwavelength photometric monitoring of WD 1145+017, a white dwarf exhibiting periodic dimming events interpreted to be the transits of orbiting, disintegrating planetesimals. Our observations include the first set of near-infrared light curves for the object, obtained on multiple nights over the span of 1 month, and recorded multiple transit events with depths varying between ∼20 and 50 per cent. Simultaneous near-infrared and optical observations of the deepest and longest duration transit event were obtained on two epochs with the Anglo-Australian Telescope and three optical facilities, over the wavelength range of 0.5–1.2μm. These observations revealed no measurable difference in transit depths for multiple photometric pass bands, allowing us to place a 2σ lower limit of 0.8μm on the grain size in the putative transiting debris cloud. This conclusion is consistent with the spectral energy distribution of the system, which can be fit with an optically thin debris disc with minimum particle sizes of 10+5−3μm
HATS-37Ab and HATS-38b: Two transiting hot neptunes in the desert
We report the discovery of two transiting Neptunes by the HATSouth survey. The planet HATS-37Ab has a mass of 0.099 +- 0.042 MJ (31.5 +- 13.4 M) and a radius of 0.606 +- 0.016 RJ, and is on a P = 4.3315 day orbit around a V = 12.266 +- 0.030 mag, 0.843-+0.0120.017 M☉ star with a radius of 0.877-+0.0120.019 R☉. We also present evidence that the star HATS-37A has an unresolved stellar companion HATS-37B, with a photometrically estimated mass of 0.654 +- 0.033 M☉. The planet HATS-38b has a mass of 0.074 +- 0.011 MJ (23.5 +- 3.5 M) and a radius of 0.614 +- 0.017 RJ, and is on a P = 4.3750 day orbit around a V = 12.411 +- 0.030 mag, 0.890-+0.0120.016 M☉ star with a radius of 1.105 +- 0.016 R☉. Both systems appear to be old, with isochrone-based ages of 11.46-+1.450.79 Gyr, and 11.89 +- 0.60 Gyr, respectively. Both HATS-37Ab and HATS-38b lie in the Neptune desert and are thus examples of a population with a low occurrence rate. They are also among the lowest-mass planets found from ground-based wide-field surveys to date.Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. This research has made use of the NASA Exoplanet Archive,
which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Progra
HATS-17b: A TRANSITING COMPACT WARM JUPITER in A 16.3 DAY CIRCULAR ORBIT
We report the discovery of HATS-17b, the first transiting warm Jupiter of the HATSouth network. HATS-17b transits its bright (V = 12.4) G-type ( = , = ) metal-rich ([Fe/H] = +0.3 dex) host star in a circular orbit with a period of P = days. HATS-17b has a very compact radius of given its Jupiter-like mass of . Up to 50% of the mass of HATS-17b may be composed of heavy elements in order to explain its high density with current models of planetary structure. HATS-17b is the longest period transiting planet discovered to date by a ground-based photometric survey, and is one of the brightest transiting warm Jupiter systems known. The brightness of HATS-17 will allow detailed follow-up observations to characterize the orbital geometry of the system and the atmosphere of the planet
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