EVIDENCE FOR a STRONG END-ON BAR IN THE RINGED Σ-Drop GALAXY NGC 6503

Freeland, Emily; Chomiuk, Laura; Keenan, Ryan; Nelson, Tyler

doi:10.1088/0004-6256/139/3/865

Cited by 7 publications

(13 citation statements)

References 44 publications

(58 reference statements)

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“…The same authors postulate that while this galaxy is possibly one of the rare cases of ring spirals classed as unbarred 2 , it is most likely to actually be barred. Indeed, both the HI velocity field (Bottema & Gerritsen 1997) and near-IR imaging (Freeland et al 2010) support the presence of a strong end-on bar. Moreover, Freeland et al (2010) argue that the previously identified nuclear ring is instead an inner ring spanned in diameter by the bar (Fig.…”

Section: Introductionmentioning

confidence: 93%

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Hierarchical star formation across the ring galaxy NGC 6503

Gouliermis¹,

Thilker²,

Elmegreen³

et al. 2015

Mon. Not. R. Astron. Soc.

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We present a detailed clustering analysis of the young stellar population across the starforming ring galaxy NGC 6503, based on the deep HST photometry obtained with the Legacy ExtraGalactic UV Survey (LEGUS). We apply a contour-based map analysis technique and identify in the stellar surface density map 244 distinct star-forming structures at various levels of significance. These stellar complexes are found to be organized in a hierarchical fashion with 95% being members of three dominant super-structures located along the star-forming ring. The size distribution of the identified structures and the correlation between their radii and numbers of stellar members show power-law behaviors, as expected from scale-free processes. The self-similar distribution of young stars is further quantified from their autocorrelation function, with a fractal dimension of ∼ 1.7 for length-scales between ∼ 20 pc and 2.5 kpc. The young stellar radial distribution sets the extent of the star-forming ring at radial distances between 1 and 2.5 kpc. About 60% of the young stars belong to the detected stellar structures, while the remaining stars are distributed among the complexes, still inside the ring of the galaxy. The analysis of the time-dependent clustering of young populations shows a significant change from a more clustered to a more distributed behavior in a time-scale of ∼ 60 Myr. The observed hierarchy in stellar clustering is consistent with star formation being regulated by turbulence across the ring. The rotational velocity difference between the edges of the ring suggests shear as the driving mechanism for this process. Our findings reveal the interesting case of an inner ring forming stars in a hierarchical fashion.

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Section: Introductionmentioning

confidence: 93%

“…Indeed, both the HI velocity field (Bottema & Gerritsen 1997) and near-IR imaging (Freeland et al 2010) support the presence of a strong end-on bar. Moreover, Freeland et al (2010) argue that the previously identified nuclear ring is instead an inner ring spanned in diameter by the bar (Fig. 1).…”

Section: Introductionmentioning

confidence: 93%

Hierarchical star formation across the ring galaxy NGC 6503

Gouliermis¹,

Thilker²,

Elmegreen³

et al. 2015

Mon. Not. R. Astron. Soc.

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“…Freeland et al (, hereafter F10) present WIYN High‐resolution Infrared Camera (WHIRC) H ‐band (1.6 μm) imaging, in combination with multiwavelength archival imaging and data from the literature, to investigate the origin(s) of the observed star‐forming ring and central σ‐drop. They find a plateau in the surface brightness profile (Freeman Type II behaviour; Freeman ) and several structures in the disc in addition to the star‐forming ring: an end‐on bar, a circumnuclear disc and a nuclear spiral.…”

Section: Introductionmentioning

confidence: 99%

Searching for non-axisymmetries in NGC 6503: a weak end-on bar

Naray

Arsenault

Spekkens

et al. 2012

Monthly Notices of the Royal Astronomical Society

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The isolation, simple apparent structure and low luminosity of the nearby spiral galaxy NGC 6503 make it an ideal candidate for an in-depth kinematic and photometric study. We introduce a new publicly available code, DISKFIT, that implements procedures for fitting nonaxisymmetries in either kinematic or photometric data. We use DISKFIT to analyse new Hα and CO velocity field data as well as H I kinematics from Greisen et al. to search for noncircular motions in the disc of NGC 6503. We find NGC 6503 to have remarkably regular gas kinematics that are well described by rotation only. We also use DISKFIT and a new K s -band image of NGC 6503 to constrain photometric models of the disc, bar and bulge. We find the galaxy to be photometrically dominated by the disc. We find NGC 6503 to contain a faint bar and an exponential bulge which together contribute only ∼5 per cent of the total galaxy light. The combination of our kinematic and photometric DISKFIT models suggests that NGC 6503 contains a weak, end-on bar that may have produced its Type II surface brightness profile but is unlikely to be responsible for its strong σ -drop.

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“…The effect of a bar on the rotation curve is a potential complication, as NGC 6503 is now known to possess an end-on bar (Freeland et al 2010). Because the bar is end-on, it is unlikely to significantly affect measurements of either the stellar or gas rotation, and we therefore do not anticipate any significant bias to our results.…”

Section: Potential Complicationsmentioning

confidence: 91%

Detecting Adiabatic Contraction in Rotation Curves

Puglielli

2011

ApJ

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We examine the structure of adiabatically contracted Einasto profiles, using the prescriptions of Blumenthal et al. and Gnedin et al., and its impact on rotation curves. Adiabatically contracted halos display a central power index of ∼0.7 ± 0.1 for nearly all values of the Einasto shape parameter α, and are well fit inside 1 kpc by double power laws. However, attempts to fit exponential disk and uncontracted halos to adiabatically contracted rotation curves yield disk masses and central power indices that are too large. We also determine whether or not the rotation curve of NGC 6503 displays evidence of adiabatic contraction using previously published bar formation constraints, and find that NGC 6503 most likely has a minimally contracted halo. However, this conclusion depends on the correct choice of circular velocity curve.

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EVIDENCE FOR a STRONG END-ON BAR IN THE RINGED Σ-Drop GALAXY NGC 6503

Cited by 7 publications

References 44 publications

Hierarchical star formation across the ring galaxy NGC 6503

Hierarchical star formation across the ring galaxy NGC 6503

Searching for non-axisymmetries in NGC 6503: a weak end-on bar

Detecting Adiabatic Contraction in Rotation Curves

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