학술논문
Multiple Star Systems in the Orion Nebula
Document Type
Working Paper
Author
GRAVITY collaboration; Karl, Martina; Pfuhl, Oliver; Eisenhauer, Frank; Genzel, Reinhard; Grellmann, Rebekka; Habibi, Maryam; Abuter, Roberto; Accardo, Matteo; Amorim, António; Anugu, Narsireddy; Ávila, Gerardo; Benisty, Myriam; Berger, Jean-Philippe; Bland, Nicolas; Bonnet, Henri; Bourget, Pierre; Brandner, Wolfgang; Brast, Roland; Buron, Alexander; Garatti, Alessio Caratti o; Chapron, Frédéric; Clénet, Yann; Collin, Claude; Foresto, Vincent Coudé du; de Wit, Willem-Jan; de Zeeuw, Tim; Deen, Casey; Delplancke-Ströbele, Françoise; Dembet, Roderick; Derie, Frédéric; Dexter, Jason; Duvert, Gilles; Ebert, Monica; Eckart, Andreas; Esselborn, Michael; Fédou, Pierre; Finger, Gert; Garcia, Paulo; Dabo, Cesar Enrique Garcia; Lopez, Rebeca Garcia; Gao, Feng; Gandron, Éric; Gillessen, Stefan; Gonté, Frédéric; Gordo, Paulo; Grözinger, Ulrich; Guajardo, Patricia; Guieu, Sylvain; Haguenauer, Pierre; Hans, Oliver; Haubois, Xavier; Haug, Marcus; Haußmann, Frank; Henning, Thomas; Hippler, Stefan; Horrobin, Matthew; Huber, Armin; Hubert, Zoltan; Hubin, Norbert; Hummel, Christian A.; Jakob, Gerd; Jochum, Lieselotte; Jocou, Laurent; Kaufer, Andreas; Kellner, Stefan; Kandrew, Sarah; Kern, Lothar; Kervella, Pierre; Kiekebusch, Mario; Klein, Ralf; Köhler, Rainer; Kolb, Johan; Kulas, Martin; Lacour, Sylvestre; Lapeyrère, Vincent; Lazareff, Bernard; Bouquin, Jean-Baptiste Le; Léna, Pierre; Lenzen, Rainer; Lévêque, Samuel; Lin, Chien-Cheng; Lippa, Magdalena; Magnard, Yves; Mehrgan, Leander; Mérand, Antoine; Moulin, Thibaut; Müller, Eric; Müller, Friedrich; Neumann, Udo; Oberti, Sylvain; Ott, Thomas; Pallanca, Laurent; Panduro, Johana; Pasquini, Luca; Paumard, Thibaut; Percheron, Isabelle; Perraut, Karine; Perrin, Guy; Pflüger, Andreas; Duc, Thanh Phan; Plewa, Philipp M.; Popovic, Dan; Rabien, Sebastian; Ramírez, Andrés; Ramos, Jose; Rau, Christian; Riquelme, Miguel; Rodríguez-Coira, Gustavo; Rohloff, Ralf-Rainer; Rosales, Alejandra; Rousset, Gérard; Sanchez-Bermudez, Joel; Scheithauer, Silvia; Schöller, Markus; Schuhler, Nicolas; Spyromilio, Jason; Straub, Odele; Straubmeier, Christian; Sturm, Eckhard; Suarez, Marcos; Tristram, Konrad R. W.; Ventura, Noel; Vincent, Frédéric; Waisberg, Idel; Wank, Imke; Widmann, Felix; Wieprecht, Ekkehard; Wiest, Michael; Wiezorrek, Erich; Wittkowski, Markus; Woillez, Julien; Wolff, Burkhard; Yazici, Senol; Ziegler, Denis; Zins, Gérard
Source
A&A 620, A116 (2018)
Subject
Language
Abstract
This work presents an interferometric study of the massive-binary fraction in the Orion Trapezium Cluster with the recently comissioned GRAVITY instrument. We observe a total of 16 stars of mainly OB spectral type. We find three previously unknown companions for $\theta ^1$ Ori B, $\theta ^2$ Ori B, and $\theta ^2$ Ori C. We determine a separation for the previously suspected companion of NU Ori. We confirm four companions for $\theta ^1$ Ori A, $\theta ^1$ Ori C, $\theta ^1$ Ori D, and $\theta ^2$ Ori A, all with substantially improved astrometry and photometric mass estimates. We refine the orbit of the eccentric high-mass binary $\theta ^1$ Ori C and we are able to derive a new orbit for $\theta ^1$ Ori D. We find a system mass of 21.7 $M_{\odot}$ and a period of $53$ days. Together with other previously detected companions seen in spectroscopy or direct imaging, eleven of the 16 high-mass stars are multiple systems. We obtain a total number of 22 companions with separations up to 600 AU. The companion fraction of the early B and O stars in our sample is about 2, significantly higher than in earlier studies of mostly OB associations. The separation distribution hints towards a bimodality. Such a bimodality has been previously found in A stars, but rarely in OB binaries, which up to this point have been assumed to be mostly compact with a tail of wider companions. We also do not find a substantial population of equal-mass binaries. The observed distribution of mass ratios declines steeply with mass, and like the direct star counts, indicates that our companions follow a standard power law initial mass function. Again, this is in contrast to earlier findings of flat mass ratio distributions in OB associations. We exclude collision as a dominant formation mechanism but find no clear preference for core accretion or competitive accretion.
Comment: Accepted for publication in A&A
Comment: Accepted for publication in A&A