Adaptive Optics Near-Infrared Imaging of R136 in 30 Doradus: The Stellar Population of a Nearby Starburst

Brandl, Bernhard R.; Sams, B.; Bertoldi, F.; Eckart, A.; Genzel, R.; Drapatz, S.; Hofmann, R.; Loewe, Michael; Quirrenbach, A.

doi:10.1086/177507

Cited by 150 publications

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“…The estimated MF slopes are consistent with the values estimated by Malumuth & Heap (1994), Hunter et al (1996), and Selman et al (1999) for the core of R 136. These values are flatter than the values estimated by Massey & Hunter (1998) and Brandl et al (1996). Table 4 shows the MF slopes estimated for R 136 in previous works for different mass range and regions.…”

Section: Discussionmentioning

confidence: 61%

Uncrowding R 136 from VLT/SPHERE extreme adaptive optics

Khorrami

Vakili

Lanz

et al. 2017

A&A

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This paper presents the sharpest near-IR images of the massive cluster R 136 to date, based on the extreme adaptive optics of the SPHERE focal instrument implemented on the ESO Very Large Telescope and operated in its IRDIS imaging mode. The crowded stellar population in the core of the R 136 starburst compact cluster remains still to be characterized in terms of individual luminosities, age, mass and multiplicity. SPHERE/VLT and its high contrast imaging possibilities open new windows to make progress on these questions. Stacking-up a few hundreds of short exposures in J and Ks spectral bands over a field of view (FoV) of 10.9 × 12.3 centered on the R 136a1 stellar component, enabled us to carry a refined photometric analysis of the core of R 136. We detected 1110 and 1059 sources in J and Ks images respectively with 818 common sources. Thanks to better angular resolution and dynamic range, we found that more than 62.6% (16.5%) of the stars, detected both in J and Ks data, have neighbours closer than 0.2 (0.1 ). The closest stars are resolved down to the full width at half maximum (FWHM) of the point spread function (PSF) measured by Starfinder. Among resolved and/or detected sources R 136a1 and R 136c have optical companions and R 136a3 is resolved as two stars (PSF fitting) separated by 59 ± 2 mas. This new companion of R 136a3 presents a correlation coefficient of 86% in J and 75% in Ks. The new set of detected sources were used to re-assess the age and extinction of R 136 based on 54 spectroscopically stars that have been recently studied with HST slit-spectroscopy (Crowther et al. 2016, MNRAS, 458, 624) of the core of this cluster. Over 90% of these 54 sources identified visual companions (closer than 0.2 ). We found the most probable age and extinction for these sources are 1.8 +1.2 −0.8 Myr, A J = (0.45 ± 0.5) mag and A K = (0.2 ± 0.5) mag within the photometric and spectroscopic error-bars. Additionally, using PARSEC evolutionary isochrones and tracks, we estimated the stellar mass range for each detected source (common in J and K data) and plotted the generalized histogram of mass (MF with error-bars). Using SPHERE data, we have gone one step further and partially resolved and studied the initial mass function covering mass range of (3-300) M at the age of 1 and 1.5 Myr. The density in the core of R 136 (0.1-1.4 pc) is estimated and extrapolated in 3D and larger radii (up to 6 pc). We show that the stars in the core are still unresolved due to crowding, and the results we obtained are upper limits. Higher angular resolution is mandatory to overcome these difficulties.

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Section: Discussionmentioning

confidence: 61%

Uncrowding R 136 from VLT/SPHERE extreme adaptive optics

Khorrami

Vakili

Lanz

et al. 2017

A&A

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“…This implication has an important consequence for understanding the early dynamical evolution of star clusters since it suggests that mass segregation in young clusters (the necessary condition for effective production of runaway OB stars) should be primordial rather than caused by the Spitzer instability. For example, R136 was found to already be mass-segregated at its age of about 2 Myr or younger (Campbell et al 1992;Hunter et al 1995;Brandl et al 1996;de Grijs et al 2002). But the Spitzer instability could be a very fast ( < ∼ 0.5 Myr) process if the birth cluster is very dense (e.g.…”

Section: Discussionmentioning

confidence: 99%

Massive runaway stars in the Large Magellanic Cloud

Gvaramadze

Kroupa

Pflamm-Altenburg

2010

A&A

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The origin of massive field stars in the Large Magellanic Cloud (LMC) has long been an enigma. The recent measurements of large offsets (∼100 km s −1 ) between the heliocentric radial velocities of some very massive (O2-type) field stars and the systemic LMC velocity provides a possible explanation of this enigma and suggests that the field stars are runaway stars ejected from their birthplaces at the very beginning of their parent cluster's dynamical evolution. A straightforward way to prove this explanation is to measure the proper motions of the field stars and to show that they are moving away from one of the nearby star clusters or OB associations. This approach is, however, complicated by the long distance to the LMC, which makes accurate proper motion measurements difficult. We used an alternative approach for solving the problem (first applied for Galactic field stars), based on the search for bow shocks produced by runaway stars. The geometry of detected bow shocks would allow us to infer the direction of stellar motion, thereby determining their possible parent clusters. In this paper we present the results of a search for bow shocks around six massive field stars that have been proposed as candidate runaway stars. Using archival Spitzer Space Telescope data, we found a bow shock associated with one of our programme stars, the O2 V((f*)) star BI 237, which is the first-ever detection of bow shocks in the LMC. Orientation of the bow shock suggests that BI 237 was ejected from the OB association LH 82 (located at 120 pc in projection from the star). A by-product of our search is the detection of bow shocks generated by four OB stars in the field of the LMC and an arc-like structure attached to the candidate luminous blue variable R81 (HD 269128). The geometry of two of these bow shocks is consistent with the possibility that their associated stars were ejected from the 30 Doradus star-forming complex. We discuss implications of our findings for the problem of the origin of runaway stars and the early dynamical evolution of star clusters.

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“…A nearby example of this effect is the young, massive cluster R136 in the 30 Doradus nebula in the Large Magellanic Cloud (LMC). Brandl et al (1996) found that the mass function in R136 steepens with increasing distance from the cluster center, indicating strong mass segregation.…”

Section: Mass Segg Regg Ationmentioning

confidence: 93%

Mass Segregation and the Initial Mass Function of Super Star Cluster M82‐F

McCrady

Graham

Vacca

2005

ApJ

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We investigate the initial mass function and mass segregation in super star cluster M82-F with high-resolution Keck NIRSPEC echelle spectroscopy. Cross-correlation with template supergiant spectra provides the velocity dispersion of the cluster, enabling measurement of the kinematic (virial) mass of the cluster when combined with sizes from NICMOS and Advanced Camera for Surveys (ACS) images. We find a mass of 6:6 AE 0:9 ; 10 5 M based on near-IR light and 7:0 AE 1:2 ; 10 5 M based on optical light. Using PSF-fitting photometry, we derive the cluster's light-to-mass (L/M ) ratio in both near-IR and optical light and compare to population-synthesis models. The ratios are inconsistent with a normal stellar initial mass function for the adopted age of 40-60 Myr, suggesting a deficiency of low-mass stars within the volume sampled. King model light profile fits to new Hubble Space Telescope ACS images of M82-F, in combination with fits to archival near-IR images, indicate mass segregation in the cluster. As a result, the virial mass represents a lower limit on the mass of the cluster.

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Adaptive Optics Near-Infrared Imaging of R136 in 30 Doradus: The Stellar Population of a Nearby Starburst

Cited by 150 publications

References 0 publications

Uncrowding R 136 from VLT/SPHERE extreme adaptive optics

Uncrowding R 136 from VLT/SPHERE extreme adaptive optics

Massive runaway stars in the Large Magellanic Cloud

Mass Segregation and the Initial Mass Function of Super Star Cluster M82‐F

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