2018A&A...620A.116G

Query : 2018A&A...620A.116G

2018A&A...620A.116G - Astronomy and Astrophysics, volume 620A, 116-116 (2018/12-1)

Multiple star systems in the Orion nebula.

GRAVITY COLLABORATION, KARL M., PFUHL O., EISENHAUER F., GENZEL R., GRELLMANN R., HABIBI M., ABUTER R., ACCARDO M., AMORIM A., ANUGU N., AVILA G., BENISTY M., BERGER J.-P., BLIND N., BONNET H., BOURGET P., BRANDNER W., BRAST R., BURON A., CARATTI O GARATTI A., CHAPRON F., CLENET Y., COLLIN C., COUDE DU FORESTO V., DE WIT W.-J., DE ZEEUW T., DEEN C., DELPLANCKE-STROBELE F., DEMBET R., DERIE F., DEXTER J., DUVERT G., EBERT M., ECKART A., ESSELBORN M., FEDOU P., FINGER G., GARCIA P., GARCIA DABO C.E., GARCIA LOPEZ R., GAO F., GENDRON E., GILLESSEN S., GONTE F., GORDO P., GROZINGER U., GUAJARDO P., GUIEU S., HAGUENAUER P., HANS O., HAUBOIS X., HAUG M., HAUSSMANN F., HENNING T., HIPPLER S., HORROBIN M., HUBER A., HUBERT Z., HUBIN N., JAKOB G., JOCHUM L., JOCOU L., KAUFER A., KELLNER S., KENDREW S., KERN L., KERVELLA P., KIEKEBUSCH M., KLEIN R., KOHLER R., KOLB J., KULAS M., LACOUR S., LAPEYRERE V., LAZAREFF B., LE BOUQUIN J.-B., LENA P., LENZEN R., LEVEQUE S., LIN C.-C., LIPPA M., MAGNARD Y., MEHRGAN L., MERAND A., MOULIN T., MULLER E., MULLER F., NEUMANN U., OBERTI S., OTT T., PALLANCA L., PANDURO J., PASQUINI L., PAUMARD T., PERCHERON I., PERRAUT K., PERRIN G., PFLUGER A., DUC T.P., PLEWA P.M., POPOVIC D., RABIEN S., RAMIREZ A., RAMOS J., RAU C., RIQUELME M., RODRIGUEZ-COIRA G., ROHLOFF R.-R., ROSALES A., ROUSSET G., SANCHEZ-BERMUDEZ J., SCHEITHAUER S., SCHOLLER M., SCHUHLER N., SPYROMILIO J., STRAUB O., STRAUBMEIER C., STURM E., SUAREZ M., TRISTRAM K.R.W., VENTURA N., VINCENT F., WAISBERG I., WANK I., WIDMANN F., WIEPRECHT E., WIEST M., WIEZORREK E., WITTKOWSKI M., WOILLEZ J., WOLFF B., YAZICI S., ZIEGLER D. and ZINS G.

Abstract (from CDS):

This work presents an interferometric study of the massive-binary fraction in the Orion Trapezium cluster with the recently comissioned GRAVITY instrument. We observed a total of 16 stars of mainly OB spectral type. We find three previously unknown companions for θ¹ Ori B, θ² Ori B, and θ² Ori C. We determined a separation for the previously suspected companion of NU Ori. We confirm four companions for θ¹ Ori A, θ¹ Ori C, θ¹ Ori D, and θ² Ori A, all with substantially improved astrometry and photometric mass estimates. We refined the orbit of the eccentric high-mass binary θ¹ Ori C and we are able to derive a new orbit for θ¹ Ori D. We find a system mass of 21.7M_☉ 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 two, significantly higher than in earlier studies of mostly OB associations. The separation distribution hints toward 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 excluded collision as a dominant formation mechanism but find no clear preference for core accretion or competitive accretion.

Abstract Copyright: © ESO 2018

Journal keyword(s): techniques: interferometric - astrometry - celestial mechanics - binaries: close - binaries: general - stars: massive

Simbad objects: 19

Full paper

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Number of rows : 19

N	Identifier	Otype	ICRS (J2000) RA	ICRS (J2000) DEC	Mag U	Mag B	Mag V	Mag R	Mag I	Sp type	#ref 1850 - 2023	#notes
1	NAME Orion Nebula Cluster	OpC	05 35.0	-05 29						~	2270	0
2	HD 36982	Or*	05 35 09.8363878512	-05 27 53.216296776	8.00	8.58	8.46			B2V	206	0
3	* tet01 Ori E	SB*	05 35 15.7721814864	-05 23 09.889316700						G2IV	95	0
4	TCC 43	*	05 35 15.80180	-05 23 11.8906						~	19	0
5	* tet01 Ori A	Ae*	05 35 15.8254015008	-05 23 14.334699480	5.87	6.75	6.73	6.42	6.21	B0V	481	1
6	TCC 59	Y*O	05 35 16.10855	-05 23 14.2457						~	29	0
7	* tet01 Ori B	EB*	05 35 16.1339860056	-05 23 06.784444248	7.71	8.20	7.96			B1V	365	2
8	* tet01 Ori C	SB*	05 35 16.4662967280	-05 23 22.921811880	4.20	5.15	5.13	4.91	4.73	O7Vp	1386	1
9	NAME Ori Trapezium	OpC	05 35 16.5	-05 23 14						~	1599	1
10	* tet01 Ori F	Em*	05 35 16.7270624568	-05 23 25.197757584	9.928	10.075	10.122		9.652	B8	42	0
11	M 42	HII	05 35 17	-05 23.4						~	4026	0
12	* tet01 Ori D	Y*O	05 35 17.2574479992	-05 23 16.570738104	6.08	6.79	6.70	6.40	6.20	B1.5Vp	325	0
13	* tet02 Ori A	SB*	05 35 22.9012398264	-05 24 57.832632108	5.37	6.30	6.39	6.30	6.35	O9.5IVp	537	0
14	* tet02 Ori B	Y*O	05 35 26.4007537560	-05 25 00.793767576	5.36	6.29	6.38	6.29	11.050	B0.7V	193	0
15	HD 37061	Or*	05 35 31.3649044920	-05 16 02.582064192	6.44	7.09	6.83			O9.5V	354	0
16	* tet02 Ori C	Or*	05 35 31.4311124640	-05 25 16.371705000		7.80	8.24			B4V	129	1
17	Brun 862	s*r	05 35 47.0099803752	-05 17 56.964353604		16.093	13.728		8.626	K3-M0I	24	0
18	HD 37115	Be*	05 35 54.078288	-05 37 42.31308	6.45	8.88	8.77	8.07		B7Ve	101	0
19	HD 37150	*	05 36 15.0278258688	-05 38 52.514534220	5.52	6.34	6.51			B3III/IV	115	0

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