2015A&A...579A..99B


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.10CEST02:39:43

2015A&A...579A..99B - Astronomy and Astrophysics, volume 579A, 99-99 (2015/7-1)

A radio map of the colliding winds in the very massive binary system HD 93129A.

BENAGLIA P., MARCOTE B., MOLDON J., NELAN E., DE BECKER M., DOUGHERTY S.M. and KORIBALSKI B.S.

Abstract (from CDS):

Radio observations are an effective tool for discovering particle acceleration regions in colliding-wind binaries through detection of synchrotron radiation. Wind-collision region (WCR) models can reproduce the radio continuum spectra of massive binaries. However, key constraints for models come from high-resolution imaging. Only five WCRs have been resolved to date at radio frequencies on milliarcsec (mas) angular scales. The source HD 93129A, a prototype of the very few known O2 I stars, is a promising target for study. Recently, a second massive, early-type star about 50 mas away was discovered, and a non-thermal radio source was detected in the region. Preliminary long-baseline array data suggest that a significant fraction of the radio emission from the system comes from a putative WCR. We seek evidence that HD93129A is a massive binary system with colliding stellar winds that produce non-thermal radiation through spatially resolved images of the radio emitting regions. We completed observations with the Australian Long Baseline Array (LBA) to resolve the system at mas angular resolutions and reduced archival Australia Telescope Compact Array (ATCA) data to derive the total radio emission. We also compiled optical astrometric data of the system in a homogeneous way. We reduced historical Hubble Space Telescope data and obtained absolute and relative astrometry with milliarcsec accuracy. The astrometric analysis leads us to conclude that the two stars in HD93129A form a gravitationally bound system. The LBA data reveal an extended arc-shaped non-thermal source between the two stars, which is indicative of a WCR. The wind momentum-rate ratio of the two stellar winds is estimated. The ATCA data show a point source with a change in flux level between 2003-4 and 2008-9, which is modeled with a non-thermal power-law spectrum with spectral indices of -1.03±0.09 and -1.21±0.03, respectively. The mass-loss rates derived from the deduced thermal radio emission and from the characteristics of the WCR are consistent with estimates derived by other authors.

Abstract Copyright:

Journal keyword(s): binaries: general - stars: massive - stars: mass-loss - stars: winds, outflows - radiation mechanisms: non-thermal - radio continuum: stars

CDS comments: Table 2 calibration stars not in SIMBAD.

Simbad objects: 11

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Number of rows : 11

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 QSO J0635-7516 QSO 06 35 46.5080299 -75 16 16.815501   15.96 15.75 15.82   ~ 508 1
2 ICRF J102343.5-664648 QSO 10 23 43.53319996 -66 46 48.7177526   18.82       ~ 16 1
3 Cl Trumpler 14 OpC 10 43 56 -59 33.0   5.70 5.5     ~ 425 0
4 HD 93129A SB* 10 43 57.4584179931 -59 32 51.395115271 6.46 7.478 7.310 7.84   O2If* 146 0
5 NGC 3372 HII 10 44 19.0 -59 53 21           ~ 888 2
6 * eta Car Em* 10 45 03.5455050 -59 41 03.951060 6.37 7.034 6.21 4.90 4.41 OBepec 2201 0
7 ICRF J104742.9-621714 QSO 10 47 42.8787583575 -62 17 14.687757190   19.99       ~ 27 0
8 ICRF J105123.5-651808 QSO 10 51 23.5142233896 -65 18 08.568033794   18.5       ~ 10 1
9 QSO B1549-790 QSO 15 56 58.86989203 -79 14 04.2815029   18.80 18.800 17.84   ~ 178 1
10 ICRF J193925.0-634245 Sy2 19 39 25.02671 -63 42 45.6255   18.87 18.37 17.64   ~ 954 1
11 BD+40 4220 EB* 20 32 22.4241357648 +41 18 18.942382590 11.32 10.79 9.185     O6.5-7f+O5.5-6f 368 0

    Equat.    Gal    SGal    Ecl

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2020.07.10-02:39:43

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