ALBERT

Description: A classical nova occurs when material accreting onto the surface of a white dwarf in a close binary system ignites in a thermonuclear runaway. Complex structures observed in the ejecta at late stages could result from interactions with the companion during the common-envelope phase. Alternatively, the explosion could be intrinsically bipolar, resulting from a localized ignition on the surface of the white dwarf or as a consequence of rotational distortion. Studying the structure of novae during the earliest phases is challenging because of the high spatial resolution needed to measure their small sizes. Here we report near-infrared interferometric measurements of the angular size of Nova Delphini 2013, starting one day after the explosion and continuing with extensive time coverage during the first 43 days. Changes in the apparent expansion rate can be explained by an explosion model consisting of an optically thick core surrounded by a diffuse envelope. The optical depth of the ejected material changes as it expands. We detect an ellipticity in the light distribution, suggesting a prolate or bipolar structure that develops as early as the second day. Combining the angular expansion rate with radial velocity measurements, we derive a geometric distance to the nova of 4.54 +/- 0.59 kiloparsecs from the Sun.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schaefer, G H -- ten Brummelaar, T -- Gies, D R -- Farrington, C D -- Kloppenborg, B -- Chesneau, O -- Monnier, J D -- Ridgway, S T -- Scott, N -- Tallon-Bosc, I -- McAlister, H A -- Boyajian, T -- Maestro, V -- Mourard, D -- Meilland, A -- Nardetto, N -- Stee, P -- Sturmann, J -- Vargas, N -- Baron, F -- Ireland, M -- Baines, E K -- Che, X -- Jones, J -- Richardson, N D -- Roettenbacher, R M -- Sturmann, L -- Turner, N H -- Tuthill, P -- van Belle, G -- von Braun, K -- Zavala, R T -- Banerjee, D P K -- Ashok, N M -- Joshi, V -- Becker, J -- Muirhead, P S -- England -- Nature. 2014 Nov 13;515(7526):234-6. doi: 10.1038/nature13834. Epub 2014 Oct 26.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉The CHARA Array of Georgia State University, Mount Wilson Observatory, Mount Wilson, California 91023, USA. ; Center for High Angular Resolution Astronomy and Department of Physics and Astronomy, Georgia State University, PO Box 5060, Atlanta, Georgia 30302, USA. ; Laboratoire Lagrange, UMR 7293, Universite de Sophia-Antipolis (UNS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire de la Cote d'Azur (OCA), Boulevard de l'Observatoire, CS 34229, F-06304 Nice, Cedex 4, France. ; Department of Astronomy, University of Michigan, 941 Dennison Building, Ann Arbor, Michigan 48109, USA. ; National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, Arizona 85719, USA. ; Universite de Lyon; Universite Lyon 1, Observatoire de Lyon, 9 avenue Charles Andre, 69230 Saint Genis Laval; CNRS UMR 5574, Centre de Recherche Astrophysique de Lyon; Ecole Normale Superieure, 69007 Lyon, France. ; Department of Astronomy, Yale University, New Haven, Connecticut 06511, USA. ; Sydney Institute for Astronomy, School of Physics, University of Sydney, New South Wales 2006, Sydney, Australia. ; Research School of Astronomy and Astrophysics, Australian National University, Canberra, Australian Capital Territory 2611, Australia. ; Remote Sensing Division, Naval Research Laboratory, 4555 Overlook Avenue Southwest, Washington, DC 20375, USA. ; Departement de Physique and Centre de Recherche en Astrophysique du Quebec (CRAQ), Universite de Montreal, CP 6128, Succursale Centre-Ville, Montreal, Quebec H3C 3J7, Canada. ; Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, Arizona 86001, USA. ; Max Planck Institute for Astronomy (MPIA), Konigstuhl 17, 69117 Heidelberg, Germany. ; United States Naval Observatory, Flagstaff Station, 10391 West Naval Observatory Road, Flagstaff, Arizona 86001, USA. ; Astronomy and Astrophysics Division, Physical Research Laboratory, Navrangpura, Ahmedabad, Gujarat 380009, India. ; 1] Department of Astronomy, University of Michigan, 941 Dennison Building, Ann Arbor, Michigan 48109, USA [2] Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, California 91106, USA. ; Department of Astronomy, Boston University, Boston, Massachusetts 02215, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25363778" target="_blank"〉PubMed〈/a〉