On galaxy spiral arms’ nature as revealed by rotation frequencies

Roca-Fàbrega, S.; Valenzuela, O.; Figueras, F.; Romero-Gómez, M.; Velázquez, Héctor; Antoja, T.; Pichardo, B.

doi:10.1093/mnras/stt643

Cited by 77 publications

(80 citation statements)

References 57 publications

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“…co-rotating at all radii (e.g. Sellwood & Carlberg 1984;Grand et al 2012;Roca-Fàbrega et al 2013). One of the interpretations of the N -body simulations is that while the spiral arm features themselves are transient, their evolution in configuration space may be driven by several spiral modes present in the disc that are in fact longer-lived standing wave oscillations (lasting for about 10 rotations) similar to the original density wave theory (e.g.…”

Section: Signature Driven By the Perseus Spiral Arm?mentioning

confidence: 93%

Stars with fast Galactic rotation observed in Gaia TGAS: a signature driven by the Perseus arm?

Hunt

Kawata

Monari

et al. 2016

Monthly Notices of the Royal Astronomical Society: Letters

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We report on the detection of a small overdensity of stars in velocity space with systematically higher Galactocentric rotation velocity than the Sun by about 20 km s −1 in the Gaia Data Release 1 Tycho-Gaia astrometric solution (TGAS) data. We find these fast Galactic rotators more clearly outside of the Solar radius, compared to inside of the Solar radius. In addition, the velocity of the fast Galactic rotators is independent of the Galactocentric distance up to R − R ∼ 0.6 kpc. Comparing with numerical models, we qualitatively discuss that a possible cause of this feature is the co-rotation resonance of the Perseus spiral arm, where the stars in peri-centre phase in the trailing side of the Perseus spiral arm experience an extended period of acceleration owing to the torque from the Perseus arm.

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Section: Signature Driven By the Perseus Spiral Arm?mentioning

confidence: 93%

Stars with fast Galactic rotation observed in Gaia TGAS: a signature driven by the Perseus arm?

Hunt

Kawata

Monari

et al. 2016

Monthly Notices of the Royal Astronomical Society: Letters

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“…According to this hypothesis, the amplitudes of spiral arms change on the timescale of a galactic rotation or even less (i.e. a few hundreds of Myrs) for multiple-arm spirals (Sellwood & Carlberg 1984;Fujii et al 2011;Wada et al 2011;Grand et al 2012b;Baba et al 2013;D'Onghia et al 2013;Pettitt et al 2015;Kumamoto & Noguchi 2016), unbarred grand-design spirals (Sellwood 2011) 2 , and barred spirals (Baba et al 2009;Grand et al 2012a;Roca-Fàbrega et al 2013;Baba 2015). In contrast to the QSSS/galactic shock hypothesis, the dynamic spiral model predicts that the gas does not flow through a spiral arm, but rather effectively falls into the spiral potential minimum from both sides of the arm (referred to as 'large-scale colliding flows'; Dobbs & Bonnell 2008;Wada et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Gas velocity patterns in simulated galaxies: observational diagnostics of spiral structure theories

Baba

Morokuma-Matsui

Miyamoto

et al. 2016

Mon. Not. R. Astron. Soc.

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There are two theories of stellar spiral arms in isolated disc galaxies that model stellar spiral arms with different longevities: quasi-stationary density wave theory, which characterises spirals as rigidly rotating, long-lived patterns (i.e. steady spirals), and dynamic spiral theory, which characterises spirals as differentially rotating, transient, recurrent patterns (i.e. dynamic spirals). In order to discriminate between these two spiral models observationally, we investigated the differences between the gas velocity patterns predicted by these two spiral models in hydrodynamic simulations. We found that the azimuthal phases of the velocity patterns relative to the gas density peaks (i.e. gaseous arms) differ between the two models, as do the gas flows; nevertheless, the velocity patterns themselves are similar for both models. Such similarity suggests that the mere existence of streaming motions does not conclusively confirm the steady spiral model. However, we found that the steady spiral model shows that the gaseous arms have radial streaming motions well inside the co-rotation radius, whereas the dynamic spiral model predicts that the gaseous arms tend to have tangential streaming motions. These differences suggest that the gas velocity patterns around spiral arms will enable distinction between the spiral theories.

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“…Our project aims to fill this gap, that is, to trace the Perseus arm in the anticenter direction, both in terms of density and kinematics. We examine: 1) the stellar overdensity associated with the spiral arm; 2) the position of the dust layer relative to the arm; and 3) the radial velocity perturbation associated with the arm which will shed light on the mechanisms driving them (e.g., Sellwood 2011;Roca-Fàbrega et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Stellar physical parameters from Strömgren photometry

Monguió¹,

Figueras²,

Grosbøl³

2014

A&A

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Aims. The aim is to derive accurate stellar distances and extinctions for young stars of our survey in the Galactic anticenter direction using the Strömgren photometric system. This will allow a detailed mapping of the stellar density and absorption toward the Perseus arm. Methods. We developed a new method for deriving physical parameters from Strömgren photometry and also implemented and tested it. This is a model-based method that uses the most recent available stellar atmospheric models and evolutionary tracks to interpolate in a 3D grid of the unreddened indexes [m 1 ], [c 1 ] and Hβ. Distances derived from both this method and the classical pre-Hipparcos calibrations were tested against Hipparcos parallaxes and found to be accurate. Results. Systematic trends in stellar photometric distances derived from empirical calibrations were detected and quantified. Furthermore, a shift in the atmospheric grids in the range T eff = [7000, 9000] K was detected and a correction is proposed. The two methods were used to compute distances and reddening for ∼12 000 OBA-type stars in our Strömgren anticenter survey. Data from the IPHAS and 2MASS catalogs were used to complement the detection of emission line stars and to break the degeneracy between early and late photometric regions. We note that photometric distances can differ by more than 20%, those derived from the empirical calibrations being smaller than those derived with the new method, which agree better with the Hipparcos data.

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On galaxy spiral arms’ nature as revealed by rotation frequencies

Cited by 77 publications

References 57 publications

Stars with fast Galactic rotation observed in Gaia TGAS: a signature driven by the Perseus arm?

Stars with fast Galactic rotation observed in Gaia TGAS: a signature driven by the Perseus arm?

Gas velocity patterns in simulated galaxies: observational diagnostics of spiral structure theories

Stellar physical parameters from Strömgren photometry

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