Browsing by Author "Lachaume, Regis"
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- ItemA discontinuity in the Teff-radius relation of M-dwarfs.(2019) Rabus, Markus; Lachaume, Regis; Jordán Colzani, Andrés Cristóbal; Brahm Scott, Rafael; Boyajian,Tabetha.; Von Braun, Kaspar.; Espinoza Pérez, Néstor; Berger, Jean-Philippe.; Le Bouquin, Jean-Baptiste.; Olivier Absil.
- ItemA family portrait of disk inner rims around Herbig Ae/Be stars Hunting for warps, rings, self shadowing, and misalignments in the inner astronomical units(2020) Kluska, J.; Berger, J. P.; Malbet, F.; Lazareff, B.; Benisty, M.; Le Bouquin, J. B.; Absil, O.; Baron, F.; Delboulbe, A.; Lachaume, Regis; Duvert, G.; Isella, A.; Jocou, L.; Juhasz, A.; Kraus, S.; Menard, F.; Millan Gabet, R.; Monnier, J. D.; Moulin, T.; Perraut, K.; Pinte, C.; Rochat, S.; Soulez, F.; Tallon, M.; Thi, W. F.; Thiebaut, E.; Traub, W.; Zins, G.
- ItemBandwidth smearing in infrared long-baseline interferometry. Application to stellar companion search in fringe-scanning mode(2013) Lachaume, Regis; Berger, Jean Philippe
- ItemBias-free model fitting of correlated data in interferometry(2021) Lachaume, RegisIn optical and infrared long-baseline interferometry, data often display significant correlated errors because of uncertain multiplicative factors such as the instrumental transfer function or the pixel-to-visibility matrix. In the context of model fitting, this situation often leads to a significant bias in the model parameters. In the most severe cases, this can can result in a fit lying outside of the range of measurement values. This is known in nuclear physics as Peelle's Pertinent Puzzle. I show how this arises in the context of interferometry and determine that the relative bias is of the order of the square root of the correlated component of the relative uncertainty times the number of measurements. It impacts preferentially large datasets, such as those obtained in medium to high spectral resolution. I then give a conceptually simple and computationally cheap way to avoid the issue: model the data without covariances, estimate the covariance matrix by error propagation using the modelled data instead of the actual data, and perform the model fitting using the covariance matrix. I also show that a more imprecise but also unbiased result can be obtained from ignoring correlations in the model fitting.
- ItemClose binary companions of the HAeBe stars LkHα 198, Elias 1, HK Ori and V380 Ori.(2005) Smith, K. W.; Balega, Y. Y.; Lachaume, Regis; Duschl, W. J.; Hofmann, K.-H.; Preibisch, T.; Schertl, D.; Weigelt, G.
- ItemDisks around young stars with VLTI/MIDI.(2006) Boekel, Roy van; Lachaume, Regis; Abraham, Peter.; Correia, Serge.; Koter, Alex de; Dominik, Carsten.; Dutrey, Anne.; Henning, Thomas.; Kospal, Agnes.; Leinert, Christoph.; Linz, Hendrik.
- ItemEvidence for very nearby hidden white dwarfs.(2016) Fuhrmann, K.; Lachaume, Regis; Chini, R.; Kaderhandt, L.; Chen, Z .
- ItemK2-161b : a low-density super-Neptune on an eccentric orbit.(2018) Brahm Scott, Rafael; Espinoza, N.; Rabus, Markus; Jordán Colzani, Andrés Cristóbal; Lachaume, Regis; Rojas Aracena, Felipe Alberto.; Zapata Sapiencia, Alvaro Mauricio.; Cortés, C.; Drass, Holger; Díaz, M.R.; Vučković, M.
- ItemK2-232 b : a transiting warm Saturn on an eccentric P = 11.2 d orbit around a V = 9.9 star.(2018) Brahm Scott, Rafael; Lachaume, Regis; Jordán Colzani, Andrés Cristóbal; Rojas Aracena, Felipe Alberto.; Rabus, Markus; Drass, Holger; Espinoza, N.; Sarkis, P.; Díaz, M.R.; Soto, M.G.; Jenkins, J.S.
- ItemK2-237 b and K2-238 b : discovery and characterization of two new transiting hot Jupiters from K2.(2018) Soto, M.G.; Lachaume, Regis; Rojas Aracena, Felipe Alberto.; Brahm Scott, Rafael; Drass, Holger; Rabus, Markus; Díaz, M.R.; Jenkins, J.S.; Espinoza, N.; Jones Fernández, Matías Ignacio; Hartman, JD.
- ItemK2-287 b : An Eccentric Warm Saturn Transiting a G-dwarf(2019) Jordán Colzani, Andrés Cristóbal; Brahm Scott, Rafael; Espinoza Pérez, Néstor; Cortes, Cristian; Diaz, Matías; Drass, Holger; Henning, Thomas; Jenkins, James S.; Jones Fernández, Matías Ignacio; Rabus, Markus; Rojas, Felipe; Sarkis, Paula; Vučković, Maja; Zapata, Abner; Soto, Maritza G.; Bakos, Gáspár Á.; Bayliss, Daniel; Bhatti, Waqas; Csubry, Zoltan; Lachaume, Regis; Moraga, Víctor; Pantoja, Blake; Osip, David; Shporer, Avi; Suc, Vincent; Vásquez Godoy, Sergio Osmán
- ItemK2-287b: an Eccentric Warm Saturn transiting a G-dwarf(2018) Jordán Colzani, Andrés Cristóbal; Zapata, Abner; Brahm Scott, Rafael; Espinoza, N.; Drass, Holger; Rabus, Markus; Rojas Henríquez, Felipe; Lachaume, Regis; Moraga Mejías, Víctor; Cortés, Cristián; Díaz, Matías
- ItemNew insights on the AU-scale circumstellar structure of FU Orionis.(2019) Malbet, Fabien.; Lachaume, Regis; Rojas Aracena, Felipe Alberto.; Brahm Scott, Rafael; Drass, Holger; Rabus, Markus; Díaz, M.R.; Jenkins, J.S.; Espinoza, N.; Jones Fernández, Matías Ignacio; Hartman, JD.
- ItemNine lensed quasars and quasar pairs discovered through spatially extended variability in Pan-STARRS(2024) Dux, Frederic; Lemon, Cameron; Courbin, Frederic; Neira, Favio; Anguita, Timo; Galan, Aymeric; Kim, Sam; Hempel, Maren; Hempel, Angela; Lachaume, RegisWe present the proof of concept of a method for finding strongly lensed quasars using their spatially extended photometric variability through difference imaging in cadenced imaging survey data. We applied the method to Pan-STARRS, starting with an initial selection of 14 107 Gaia multiplets with quasar-like infrared colours from WISE. We identified 229 candidates showing notable spatially extended variability during the Pan-STARRS survey period. These include 20 known lenses and an additional 12 promising candidates for which we obtained long-slit spectroscopy follow-up. This process resulted in the confirmation of four doubly lensed quasars, four unclassified quasar pairs, and one projected quasar pair. Only three are pairs of stars or quasar + star projections. The false-positive rate accordingly is 25%. The lens separations are between 0.81 '' and 1.24 '', and the source redshifts lie between z = 1 :47 and z = 2 :46. Three of the unclassified quasar pairs are promising dual-quasar candidates with separations ranging from 6.6 to 9.3 kpc. We expect that this technique is a particularly e fficient way to select lensed variables in the upcoming Rubin-LSST, which will be crucial given the expected limitations for spectroscopic follow-up.
- ItemOHANA and star formation : probing deep into the accretion/ejection mechanism.(2003) Malbet, Fabien.; Dougados, Catherine.; Lachaume, Regis; Monin, Jean-Louis.; Berger, Jean-Philippe.
- ItemOn marginally resolved objects in optical interferometry.(2003) Lachaume, Regis
- ItemParallaxes of southern extremely cool objects III : 118 L and T dwarfs(2018) Smart, R.L.; Bucciarelli, B.; Jones, H.R.A.; Marocco, F.; Andrei, A.H.; Goldman, B.; Mendez, R.A.; D’Avila, V.A.; Burningham, B.; Lachaume, Regis
- ItemParallaxes of Southern Extremely Cool objects III : 118 L and T dwarfs.(2018) Smart, R.L.; Lachaume, Regis; Bucciarelli, B.; Jones, H. R. A.; Marocco, F.; Andrei, A. H.; Goldman, B.; Mendez, R. A.; D’Avila, V. A.; Burningham, B.; Camargo, J. I. B.; Crosta, M. T.; Dapra, M.
- ItemProbing the inner part of protoplanetary disks with the VLTI.(2000) Malbet, Fabien.; Lachaume, Regis; Monin, Jean-Louis.; Berger, Jean-Philippe.
- ItemResolving the B[e] star Hen 3-1191 at 10 m with VLTI/MIDI.(2007) Lachaume, Regis; Preibisch, Th.; Driebe, Th.; Weigelt, G.