학술논문
Mid-infrared circumstellar emission of the long-period Cepheid l Carinae resolved with VLTI/MATISSE
Document Type
Working Paper
Author
Hocdé, V.; Nardetto, N.; Matter, A.; Lagadec, E.; Mérand, A.; Cruzalèbes, P.; Meilland, A.; Millour, F.; Lopez, B.; Berio, P.; Weigelt, G.; Petrov, R.; Isbell, J. W.; Jaffe, W.; Kervella, P.; Glindemann, A.; Schöller, M.; Allouche, F.; Gallenne, A.; de Souza, A. Domiciano; Niccolini, G.; Kokoulina, E.; Varga, J.; Lagarde, S.; Augereau, J. -C.; van Boekel, R.; Bristow, P.; Henning, Th.; Hofmann, K. -H.; Zins, G.; Danchi, W. -C.; Delbo, M.; Dominik, C.; Rosas, V. Gámez; Klarmann, L.; Hron, J.; Hogerheijde, M. R.; Meisenheimer, K.; Pantin, E.; Paladini, C.; Robbe-Dubois, S.; Schertl, D.; Stee, P.; Waters, R.; Lehmitz, M.; Bettonvil, F.; Heininger, M.; Woillez, J.; Wolf, S.; Yoffe, G.; Szabados, L.; Chiavassa, A.; Borgniet, S.; Breuval, L.; Javanmardi, B.; Ábrahám, P.; Abadie, S.; Abuter, R.; Accardo, M.; Adler, T.; Agócs, T.; Alonso, J.; Antonelli, P.; Böhm, A.; Bailet, C.; Bazin, G.; Beckmann, U.; Beltran, J.; Boland, W.; Bourget, P.; Brast, R.; Bresson, Y.; Burtscher, L.; Buter, R.; Castillo, R.; Chelli, A.; Cid, C.; Clausse, J. -M.; Connot, C.; Conzelmann, R. D.; De Haan, M.; Ebert, M.; Elswijk, E.; Fantei, Y.; Frahm, R.; Gabasch, A.; Garces, E.; Girard, P.; Glazenborg, A.; Gonté, F. Y. J.; Herrera, J. C. González; Graser, U.; Guajardo, P.; Guitton, F.; Hanenburg, H.; Haubois, X.; Hubin, N.; Huerta, R.; Idserda, J.; Ives, D.; Jakob, G.; Jaskó, A.; Jochum, L.; Klein, R.; Kragt, J.; Kroes, G.; Kuindersma, S.; Labadie, L.; Laun, W.; Poole, R. Le; Leinert, C.; Lizon, J. -L.; Lopez, M.; Marcotto, A.; Mauclert, N.; Maurer, T.; Mehrgan, L. H.; Meisner, J.; Meixner, K.; Mellein, M.; Mohr, L.; Morel, S.; Mosoni, L.; Navarro, R.; Neumann, U.; Nußbaum, E.; Pallanca, L.; Pasquini, L.; Percheron, I.; Duc, T. Phan; Pott, J. -U.; Pozna, E.; Ridinger, A.; Rigal, F.; Riquelme, M.; Rivinius, Th.; Roelfsema, R.; Rohloff, R. -R.; Rousseau, S.; Schuhler, N.; Schuil, M.; Shabun, K.; Soulain, A.; Stephan, C.; ter Horst, R.; Tromp, N.; Vakili, F.; van Duin, A.; Venema, L. B.; Vinther, J.; Wittkowski, M.; Wrhel, F.
Source
Subject
Language
Abstract
The nature of circumstellar envelopes (CSE) around Cepheids is still a matter of debate. The physical origin of their infrared (IR) excess could be either a shell of ionized gas, or a dust envelope, or both. This study aims at constraining the geometry and the IR excess of the environment of the long-period Cepheid $\ell$ Car (P=35.5 days) at mid-IR wavelengths to understand its physical nature. We first use photometric observations in various bands and Spitzer Space Telescope spectroscopy to constrain the IR excess of $\ell$ Car. Then, we analyze the VLTI/MATISSE measurements at a specific phase of observation, in order to determine the flux contribution, the size and shape of the environment of the star in the L band. We finally test the hypothesis of a shell of ionized gas in order to model the IR excess. We report the first detection in the L band of a centro-symmetric extended emission around l Car, of about 1.7$R_\star$ in FWHM, producing an excess of about 7.0\% in this band. In the N band, there is no clear evidence for dust emission from VLTI/MATISSE correlated flux and Spitzer data. On the other side, the modeled shell of ionized gas implies a more compact CSE ($1.13\pm0.02\,R_\star$) and fainter (IR excess of 1\% in the L band). We provide new evidences for a compact CSE of $\ell$ Car and we demonstrate the capabilities of VLTI/MATISSE for determining common properties of CSEs. While the compact CSE of $\ell$ Car is probably of gaseous nature, the tested model of a shell of ionized gas is not able to simultaneously reproduce the IR excess and the interferometric observations. Further Galactic Cepheids observations with VLTI/MATISSE are necessary for determining the properties of CSEs, which may also depend on both the pulsation period and the evolutionary state of the stars.
Comment: 13 pages, 8 figures, accepted in Astronomy and Astrophysics
Comment: 13 pages, 8 figures, accepted in Astronomy and Astrophysics