<i>Hubble Space Telescope</i>NICMOS Variability Study of Massive Stars in the Young Dense Galactic Starburst NGC 3603

Moffat, A. F. J.; Poitras, V.; Марченко, С. В.; Shara, Michael M.; Zurek, David; Bergeron, E.; Antokhina, É. A.

doi:10.1086/425878

Cited by 38 publications

(48 citation statements)

References 20 publications

(32 reference statements)

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“…Without such high spatial resolution, this would have been impossible in the tight core of NGC 3603. Schnurr et al's spectra confirm the binary nature of star A1 (with two unequally bright WN stars), for which deep double eclipses in a P = 3.7724d orbit were found previously from HST/NICMOS photometry (Moffat et al 2004), leading to an orbital inclination i = 71 o . Combined with the RV orbits, this yields masses of 114±30 and 84±15 M for A1.…”

Section: Ngc 3603/a1 Csupporting

confidence: 70%

Massive Binaries

Moffat

2007

Proc. IAU

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Abstract.As with all binaries, those that contain massive stars reveal various degrees of interaction, depending mainly on orbital separation and age, although things happen much faster in massive binaries. Those massive binaries with initial periods exceeding ∼10 years generally only interact via wind-wind collisions, with little or no effect on their subsequent evolution (unless located in dense clusters). Shorter-period systems show even stronger wind-wind collisions as a rule, but also interact more directly via Roche Lobe Overflow or Common Envelope, with dramatic effects on their evolution. If we didn't have binaries among massive stars, we would be missing a whole host of interesting phenomena in the Universe, such as sources of enhanced stellar X-ray or non-thermal radio emission, WR dust-spirals, inverse mass-ratios, very rapid spin, rejuvenation and massive blue-stragglers, enhanced cluster dynamics, many runaways and possibly even SMBHs and GRBs! On the other hand, non(or little)-interacting massive binaries are also useful to provide information on Star-Formation processes and determination of stellar parameters (such as the mass) that would otherwise be difficult or impossible to obtain from single stars. In this review, I highlight some of the developments that have occurred during the past few years since the last IAU Symposium on Massive Stars in 2002.

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Section: Ngc 3603/a1 Csupporting

confidence: 70%

Massive Binaries

Moffat

2007

Proc. IAU

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“…-Two additional examples of very massive stars in elliptical orbits whose large eccentricity made the discovery of their binarity difficult are WR 22 ≡ HD 92 740 (Moffat & Seggewiss 1978;Conti et al 1979;Schweickhardt et al 1999, WN7 + O8-9.5 III:) and HD 93 162 (Gamen et al 2008;Sota et al 2014, O2.5 If*/WN6 + OB). -There are also very massive twin systems in shorter, nearcircular orbits such as NGC 3603-A1 (Moffat et al 2004;Schnurr et al 2008, WN6ha + WN6ha), WR 20a (Rauw et al 2004;Bonanos et al 2004;Crowther & Walborn 2011 we note that σ Ori B is B0.5 V). Why were these systems not discovered earlier?…”

Section: Discussionmentioning

confidence: 65%

The little-studied cluster Berkeley 90

Apellániz

Negueruela

Barbá

et al. 2015

A&A

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Context. It appears that most (if not all) massive stars are born in multiple systems. At the same time, the most massive binaries are hard to find owing to their low numbers throughout the Galaxy and the implied large distances and extinctions. Aims. We want to study LS III +46 11, identified in this paper as a very massive binary; another nearby massive system, LS III +46 12; and the surrounding stellar cluster, Berkeley 90. Methods. Most of the data used in this paper are multi-epoch high S/N optical spectra, although we also use Lucky Imaging and archival photometry. The spectra are reduced with dedicated pipelines and processed with our own software, such as a spectroscopicorbit code, CHORIZOS, and MGB. Results. LS III +46 11 is identified as a new very early O-type spectroscopic binary [O3.5 If* + O3.5 If*] and LS III +46 12 as another early O-type system [O4.5 V((f))]. We measure a 97.2-day period for LS III +46 11 and derive minimum masses of 38.80 ± 0.83 M and 35.60 ± 0.77 M for its two stars. We measure the extinction to both stars, estimate the distance, search for optical companions, and study the surrounding cluster. In doing so, a variable extinction is found as well as discrepant results for the distance. We discuss possible explanations and suggest that LS III +46 12 may be a hidden binary system where the companion is currently undetected.

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“…Based on HST NICMOS data, Moffat et al (2004) suggested that A1 is possibly an eclipsing binary system with a 30Y90 M H-rich WR component ( WN6ha) and a 25Y50 M O star companion. The source B also has been suggested to be a binary system (e.g., Moffat 1983).…”

Section: Main-sequence Starsmentioning

confidence: 99%

The Initial Mass Function of the Massive Star‐forming Region NGC 3603 from Near‐Infrared Adaptive Optics Observations

Harayama

Eisenhauer

Martins

2008

ApJ

172

188

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We study the initial mass function (IMF) of one of the most massive Galactic star-forming regions NGC 3603 to answer a fundamental question in current astrophysics: is the IMF universal, or does it vary? Using our very deep, high angular resolution JHK S L 0 images obtained with NAOS-CONICA at the VLT at ESO, we have successfully revealed the stellar population down to the subsolar mass range in the core of the starburst cluster. The derived IMF of NGC 3603 is reasonably fitted by a single power law with index À $ À0:74 within a mass range of 0.4Y20 M , substantially flatter than the Salpeter-like IMF. A strong radial steepening of the IMF is observed mainly in the inner r P 30 0 0 field, indicating mass segregation in the cluster center. We estimate the total mass of NGC 3603 to be about 1:0Y1:6 ; 10 4 M . The derived core density is !6 ; 10 4 M pc À3 , an order of magnitude larger than, e.g., the Orion Nebula Cluster. The estimate of the half-mass relaxation time for solar-mass stars is about 10Y 40 Myr, suggesting that the intermediate-and low-mass stars have not yet been affected significantly by the dynamical relaxation in the cluster. The relaxation time for the high-mass stars can be comparable to the age of the cluster. We estimate that the stars residing outside the observed field cannot steepen the IMF significantly, indicating our IMF adequately describes the whole cluster. Analyzing thoroughly the systematic uncertainties in our IMF determination, we conclude that the power-law index of the IMF of NGC 3603 is À ¼ À0:74 þ0:62 À0:47 . Our result thus supports the hypothesis of a potential top-heavy IMF in massive star-forming clusters and starbursts.

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Hubble Space TelescopeNICMOS Variability Study of Massive Stars in the Young Dense Galactic Starburst NGC 3603

Cited by 38 publications

References 20 publications

Massive Binaries

Massive Binaries

The little-studied cluster Berkeley 90

The Initial Mass Function of the Massive Star‐forming Region NGC 3603 from Near‐Infrared Adaptive Optics Observations

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