Young Star-Forming Complexes in the Ring of the S0 Galaxy NGC 4324

Proshina, I. S.; Moiseev, A. V.; Сильченко, О. К.

doi:10.1134/s1063773722020049

Cited by 5 publications

(3 citation statements)

References 49 publications

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“…In the second paper of 2022, Proshina et al (2022) discovered a regularity in the distribution of young stellar complexes and HII regions in the ring of the lenticular (!) SA0+ galaxy NGC 4324 (Fig.…”

Section: Results Of Studies On Regularities In the Distribution Of Yo...mentioning

confidence: 99%

“…Stellar complexes of Elmegreen & Elmegreen (1983) are only a specific case of such regions with a higher concentration of the young stellar population. Proshina et al (2022) discovered a drift of star formation along the ring of NGC 4324, where relatively younger star formation regions often lie between relatively older ones. This regularity is not unique: younger and older regions alternate in most galaxies.…”

Section: Discussion Of the Resultsmentioning

confidence: 99%

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Regular Chains of Star Formation Regions in Spiral Arms and Rings of Disk Galaxies

Гусев¹

2023

Astron. Rep.

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The regularity in the distribution of young stellar groups along the spiral arms of galaxies, first discovered by Bruce and Debra Elmegreen in 1983, was considered a rather rare phenomenon. However, recent studies of the spatial regularities in the distribution of the young stellar populations along the arms of the spiral galaxies NGC 628, NGC 895, NGC 4321, NGC 5474, NGC 6946, as well as along the rings of the spiral galaxy NGC 6217 and the lenticular galaxy NGC 4324, have revealed that this spatial (quasi) regularity and/or the presence of regular chains of star-forming regions is a fairly common phenomenon. Across all galaxies, the characteristic regularity scale is 350-500 pc or a multiple thereof. It should be noted that theoretical models predict an instability scale of a stellar-gas disk on the order of a few kpc, which is several times larger than what has been observed. The paper is partly based on the report presented at the

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Section: Results Of Studies On Regularities In the Distribution Of Yo...mentioning

confidence: 99%

Section: Discussion Of the Resultsmentioning

confidence: 99%

Regular Chains of Star Formation Regions in Spiral Arms and Rings of Disk Galaxies

Гусев¹

2023

Astron. Rep.

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“…Minor merging in a system with a large disc galaxy is accompanied by the tidal stripping of the dwarf and by various disturbances in the main galaxy, including the generation of streams, tails, bridges, and rings [53][54][55][56][57]. Stellar and gas streams are an important source of information about the history of galactic evolution and provide verification of various assumptions, including estimates of dark-mass parameters [58,59].…”

Section: Introductionmentioning

confidence: 99%

Formation of Transitional cE/UCD Galaxies through Massive/Dwarf Disc Galaxy Mergers

Khoperskov,

Khrapov,

Sirotin

2023

Galaxies

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The dynamics of the merger of a dwarf disc galaxy with a massive spiral galaxy of the Milky Way type were studied in detail. The remnant of such interaction after numerous crossings of the satellite through the disc of the main galaxy was a compact stellar core, the characteristics of which were close to small compact elliptical galaxies (cEs) or large ultra-compact dwarfs (UCDs). Such transitional cE/UCD objects with an effective radius of 100–200 pc arise as a result of stripping the outer layers of the stellar core during the destruction of a dwarf disc galaxy. Numerical models of the satellite before interaction included baryonic matter (stars and gas) and dark mass. We used N-body to describe the dynamics of stars and dark matter, and we used smoothed-particle hydrodynamics to model the gas components of both galaxies. The direct method of calculating the gravitational force between all particles provided a qualitative resolution of spatial structures up to 10 pc. The dwarf galaxy fell onto the gas and stellar discs of the main galaxy almost along a radial trajectory with a large eccentricity. This ensured that the dwarf crossed the disc of the main galaxy at each pericentric approach over a time interval of more than 9 billion years. We varied the gas mass and the initial orbital characteristics of the satellite over a wide range, studying the features of mass loss in the core. The presence of the initial gas component in a dwarf galaxy significantly affects the nature of the formation and evolution of the compact stellar core. The gas-rich satellite gives birth to a more compact elliptical galaxy compared to the merging gas-free dwarf galaxy. The initial gas content in the satellite also affects the internal rotation in the stripped nucleus. The simulated cE/UCD galaxies contained very little gas and dark matter at the end of their evolution.

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Role of magnetic fields in disc galaxies: spiral arm instability

Arora,

Federrath,

Banerjee

et al. 2024

A&A

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Regularly spaced star-forming regions along the spiral arms of nearby galaxies provide insight into the early stages and initial conditions of star formation. The regular separation of these star-forming regions suggests spiral arm instability as their origin. We explore the effects of magnetic fields on the spiral arm instability. We use 3D global magnetohydrodynamical simulations of isolated spiral galaxies, comparing three different initial plasma beta values (ratios of the thermal to magnetic pressure) of $ $50$, and $10$. We perform a Fourier analysis to calculate the separation of the over-dense regions that formed as a result of the spiral instability. We then compare the separations with observations. We find that the spiral arms in the hydro case ($ are unstable. The fragments are initially connected by gas streams that are reminiscent of the Kelvin-Helmholtz instability. For $ = 50$, the spiral arms also fragment, but the fragments separate earlier and tend to be slightly elongated in the direction perpendicular to the spiral arms. However, in the $ = 10$ run, the arms are stabilised against fragmentation by magnetic pressure. Despite the difference in the initial magnetic field strengths of the $ = 50$ and $10$ runs, the magnetic field is amplified to $ arm 1$ inside the spiral arms for both runs. The spiral arms in the unstable cases (hydro and $ fragment into regularly spaced over-dense regions. We determine their separation to be $ 0.5$ kpc in the hydro and $ 0.65$ kpc in the $ = 50$ case. These two values agree with the observed values found in nearby galaxies. We find a smaller median characteristic wavelength of the over-densities along the spiral arms of $ kpc in the hydro case compared to $0.98^ $ kpc in the $ = 50$ case. Moreover, we find a higher growth rate of the over-densities in the $ = 50$ run compared to the hydro run. We observe magnetic hills and valleys along the fragmented arms in the $ = 50$ run, which is characteristic of the Parker instability.

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Young Star-Forming Complexes in the Ring of the S0 Galaxy NGC 4324

Cited by 5 publications

References 49 publications

Regular Chains of Star Formation Regions in Spiral Arms and Rings of Disk Galaxies

Regular Chains of Star Formation Regions in Spiral Arms and Rings of Disk Galaxies

Formation of Transitional cE/UCD Galaxies through Massive/Dwarf Disc Galaxy Mergers

Role of magnetic fields in disc galaxies: spiral arm instability

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