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Author Carmichael, T.W.; Quinn, S.N.; Mustill, A.J.; Huang, C.; Zhou, G.; Persson, C.M.; Nielsen, L.D.; Collins, K.A.; Ziegler, C.; Collins, K.I.; Rodriguez, J.E.; Shporer, A.; Brahm, R.; Mann, A.W.; Bouchy, F.; Fridlund, M.; Stassun, K.G.; Hellier, C.; Seidel, J.V.; Stalport, M.; Udry, S.; Pepe, F.; Ireland, M.; Zerjal, M.; Briceno, C.; Law, N.; Jordan, A.; Espinoza, N.; Henning, T.; Sarkis, P.; Latham, D.W.
Title Two Intermediate-mass Transiting Brown Dwarfs from the TESS Mission Type
Year 2020 Publication Astronomical Journal Abbreviated Journal Astron. J.
Volume 160 Issue 1 Pages 15 pp
Keywords Brown dwarfs; Radial velocity; Transit photometry; Spectroscopy; Photometry; Substellar companion stars
Abstract We report the discovery of two intermediate-mass transiting brown dwarfs (BDs), TOI-569b and TOI-1406b, from NASA's Transiting Exoplanet Survey Satellite mission. TOI-569b has an orbital period of P = 6.55604 0.00016 days, a mass of M-b = 64.1 1.9 , and a radius of R-b = 0.75 0.02 . Its host star, TOI-569, has a mass of M-star = 1.21 0.05, a radius of R-star = 1.47 0.03 dex, and an effective temperature of T-eff = 5768 110 K. TOI-1406b has an orbital period of P = 10.57415 0.00063 days, a mass of M-b = 46.0 2.7 , and a radius of R-b = 0.86 0.03 . The host star for this BD has a mass of M-star = 1.18 0.09 a radius of R-star = 1.35 0.03 dex, and an effective temperature of T-eff = 6290 100 K. Both BDs are in circular orbits around their host stars and are older than 3 Gyr based on stellar isochrone models of the stars. TOI-569 is one of two slightly evolved stars known to host a transiting BD (the other being KOI-415). TOI-1406b is one of three known transiting BDs to occupy the mass range of 40-50 and one of two to have a circular orbit at a period near 10 days (with the first being KOI-205b). Both BDs have reliable ages from stellar isochrones, in addition to their well-constrained masses and radii, making them particularly valuable as tests for substellar isochrones in the BD mass-radius diagram.
Address [Carmichael, Theron W.] Harvard Univ, Dept Astron, Cambridge, MA 02138 USA, Email: tcarmich@cfa.harvard.edu
Corporate Author Thesis
Publisher Iop Publishing Ltd Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0004-6256 ISBN Medium
Area Expedition Conference
Notes WOS:000549117200001 Approved
Call Number UAI @ eduardo.moreno @ Serial 1179
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Author Henriquez, P.A.; Ruz, G.A.
Title Noise reduction for near-infrared spectroscopy data using extreme learning machines Type
Year 2019 Publication Engineering Applications Of Artificial Intelligence Abbreviated Journal Eng. Appl. Artif. Intell.
Volume 79 Issue Pages 13-22
Keywords Near-infrared spectroscopy; Parallel layers; Constrained optimization; Regression; Classification
Abstract The near infrared (NIR) spectra technique is an effective approach to predict chemical properties and it is typically applied in petrochemical, agricultural, medical, and environmental sectors. NIR spectra are usually of very high dimensions and contain huge amounts of information. Most of the information is irrelevant to the target problem and some is simply noise. Thus, it is not an easy task to discover the relationship between NIR spectra and the predictive variable. However, this kind of regression analysis is one of the main topics of machine learning. Thus machine learning techniques play a key role in NIR based analytical approaches. Pre-processing of NIR spectral data has become an integral part of chemometrics modeling. The objective of the pre-processing is to remove physical phenomena (noise) in the spectra in order to improve the regression or classification model. In this work, we propose to reduce the noise using extreme learning machines which have shown good predictive performances in regression applications as well as in large dataset classification tasks. For this, we use a novel algorithm called C-PL-ELM, which has an architecture in parallel based on a non-linear layer in parallel with another non-linear layer. Using the soft margin loss function concept, we incorporate two Lagrange multipliers with the objective of including the noise of spectral data. Six real-life dataset were analyzed to illustrate the performance of the developed models. The results for regression and classification problems confirm the advantages of using the proposed method in terms of root mean square error and accuracy.
Address [Henriquez, Pablo A.; Ruz, Gonzalo A.] Univ Adolfo Ibanez, Fac Ingn & Ciencias, Ave Diagonal Las Torres 2640, Santiago, Chile, Email: pabhenriquez@alumnos.uai.cl;
Corporate Author Thesis
Publisher Pergamon-Elsevier Science Ltd Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0952-1976 ISBN Medium
Area Expedition Conference
Notes WOS:000459524300002 Approved
Call Number UAI @ eduardo.moreno @ Serial 984
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Author Weaver, IC.; Lopez-Morales, M.; Alam, MK.; Espinoza, N.; Rackham, BV.; Goyal, JM.; MacDonald, RJ.; Lewis, NK.; Apai, D.; Bixel, A.; Jordan, A.; Kirk, J.; McGruder, C.; Osip, DJ.
Title ACCESS: An Optical Transmission Spectrum of the High-gravity Hot Jupiter HAT-P-23b Type
Year 2021 Publication Astronomical Journal Abbreviated Journal Astron. J.
Volume 161 Issue 6 Pages 278
Keywords EXOPLANET HD 189733B; HST PANCET PROGRAM; EXTRASOLAR PLANET; CLOUDY ATMOSPHERE; CLEAR ATMOSPHERE; GIANT PLANET; WATER-VAPOR; GAS GIANT; SPECTROSCOPY; HUBBLE
Abstract We present a new ground-based visible transmission spectrum of the high-gravity, hot Jupiter HAT-P-23b, obtained as part of the ACCESS project. We derive the spectrum from five transits observed between 2016 and 2018, with combined wavelength coverage between 5200 angstrom and 9269 angstrom in 200 angstrom bins, and with a median precision of 247 ppm per bin. HAT-P-23b's relatively high surface gravity (g approximate to 30 m s(-2)), combined with updated stellar and planetary parameters from Gaia DR2, gives a five-scale-height signal of 384 ppm for a hydrogen-dominated atmosphere. Bayesian models favor a clear atmosphere for the planet with the tentative presence of TiO, after simultaneously modeling stellar contamination, using spots parameter constraints from photometry. If confirmed, HAT-P-23b would be the first example of a high-gravity gas giant with a clear atmosphere observed in transmission at optical/near-IR wavelengths; therefore, we recommend expanding observations to the UV and IR to confirm our results and further characterize this planet. This result demonstrates how combining transmission spectroscopy of exoplanet atmospheres with long-term photometric monitoring of the host stars can help disentangle the exoplanet and stellar activity signals.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0004-6256 ISBN Medium
Area Expedition Conference
Notes WOS:000655343200001 Approved
Call Number UAI @ alexi.delcanto @ Serial 1396
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