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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. doi  openurl
  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.  
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  ISSN 0004-6256 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000655343200001 Approved  
  Call Number UAI @ alexi.delcanto @ Serial 1396  
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Author van der Marel, N.; Mulders, G.D. doi  openurl
  Title A Stellar Mass Dependence of Structured Disks: A Possible Link with Exoplanet Demographics Type
  Year 2021 Publication Astronomical Journal Abbreviated Journal Astron. J.  
  Volume 162 Issue 1 Pages 28  
  Keywords GIANT PLANET OCCURRENCE; X-SHOOTER SPECTROSCOPY; MAIN-SEQUENCE STARS; CIRCLE-DOT STARS; ALMA SURVEY; PROTOPLANETARY DISKS; CIRCUMSTELLAR DISKS; TRANSITION DISKS; MILLIMETER CONTINUUM; CLASS-II  
  Abstract Gaps in protoplanetary disks have long been hailed as signposts of planet formation. However, a direct link between exoplanets and disks remains hard to identify. We present a large sample study of ALMA disk surveys of nearby star-forming regions to disentangle this connection. All disks are classified as either structured (transition, ring, extended) or nonstructured (compact) disks. Although low-resolution observations may not identify large-scale substructure, we assume that an extended disk must contain substructure from a dust evolution argument. A comparison across ages reveals that structured disks retain high dust masses up to at least 10 Myr, whereas the dust mass of compact, nonstructured disks decreases over time. This can be understood if the dust mass evolves primarily by radial drift, unless drift is prevented by pressure bumps. We identify a stellar mass dependence of the fraction of structured disks. We propose a scenario linking this dependence with that of giant exoplanet occurrence rates. We show that there are enough exoplanets to account for the observed disk structures if transitional disks are created by exoplanets more massive than Jupiter and ring disks by exoplanets more massive than Neptune, under the assumption that most of those planets eventually migrate inwards. On the other hand, the known anticorrelation between transiting super-Earths and stellar mass implies those planets must form in the disks without observed structure, consistent with formation through pebble accretion in drift-dominated disks. These findings support an evolutionary scenario where the early formation of giant planets determines the disk's dust evolution and its observational appearance.  
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  ISSN 0004-6256 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000664728300001 Approved  
  Call Number UAI @ alexi.delcanto @ Serial 1431  
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Author Kirk, J.; Rackham, B.V.; MacDonald, R.J.; Lopez-Morales, M.; Espinoza, N.; Lendl, M.; Wilson, J.; D.J.; Wheatley, P.J.; Skillen, I.; Apai, D.; Bixel, A.; Gibson, N.P.; Jordan, A.; Lewis, N.K.; Louden, T.; McGruder, C.D.; Nikolov, N.; Rodler, F.; Weaver, I.C. doi  openurl
  Title ACCESS and LRG-BEASTS: A Precise New Optical Transmission Spectrum of the Ultrahot Jupiter WASP-103b Type
  Year 2021 Publication Astronomical Journal Abbreviated Journal Astron. J.  
  Volume 162 Issue 1 Pages 34  
  Keywords GAS-GIANT EXOPLANET; HOT JUPITERS; ATMOSPHERES; TRANSIT; PLANET; EFFICIENT; SPECTROSCOPY; RETRIEVAL; CHEMISTRY; EXPLAIN  
  Abstract We present a new ground-based optical transmission spectrum of the ultrahot Jupiter WASP-103b (Teq=2484  
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  ISSN 0004-6256 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000667942900001 Approved  
  Call Number UAI @ alexi.delcanto @ Serial 1434  
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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. doi  openurl
  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 (up) 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. pdf  doi
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  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 (up) 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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