Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 1402.3558

From Filaments to Oscillating Starless Cores

Eric Keto·Andreas Burkert
View original source ↗Read source document ↗Export metadata ↓

Abstract

Long wavelength sonic oscillations are observed or inferred in many of the small, dark molecular clouds, the starless cores, that are the precursors to protostars. The oscillations provide significant internal energy and the time scale for their dissipation may control the rate of star formation in the starless cores. Despite their importance, their origin is unknown. We explore one hypothesis that the oscillations develop as a starless core forms from a filament. We model this process with a numerical hydrodynamic simulation and generate synthetic molecular line observations with a radiative transfer simulation. Comparison with actual observations shows general agreement suggesting the proposed mechanism is viable.

Explore related subjects

astro-ph.GA

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Eric Keto, Andreas Burkert. 2014-02-14. From Filaments to Oscillating Starless Cores. https://doi.org/10.1093/mnras%2Fstu379

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Dark matter dynamical friction on binary stars in the faintest dwarf galaxies: I. Analytical approach

We study binary stars moving through a uniform dark matter background and experiencing dynamical friction. The centre-of-mass motion of the pairs is taken into account. We derive formulas and timescales for the secular evolution of the orbital parameters for both wide and close binaries. Applying these results to environments typical of the faintest ultra-faint dwarf galaxies, we show that some binaries undergo significant eccentricity oscillations while their semi-major axes gradually decrease over a Hubble time. At the population level, dynamical friction depletes wide binaries and increases the fraction of highly eccentric systems. Importantly, the effect is not strongest at the highest dark matter densities, since the associated increase in velocity dispersion weakens friction. With future, more detailed theoretical studies and improving observational capabilities, binary stars may serve as a tool to probe the dark matter content of the faintest galaxies.

astro-ph.GA↗
arXiv2026

Dissecting the 3D chemo-dynamical structures of NGC~1381: A galaxy hosting an ancient slow bar with an accretion-related bulge and thick disc

We applied the barred population-orbit superposition method developed in our 2025 papers to construct 3D chemo-dynamical models for the barred S0 galaxy NGC~1381 in the Fornax cluster. Based on the stellar orbits in the models, we decomposed NGC~1381 into six components: (1) a dynamically warm nuclear disc with $f_{\rm nucl}\sim5\%$; (2) a rigidly rotating, BP/X-shaped bar with $f_{\rm bar}\sim30\%$; (3) a dynamically hot, spheroidal bulge with $f_{\rm bulge}\sim17\%$; (4) a dynamically cold thin disc with $f_{\rm thin}\sim28\%$; (5) a vertically extended thick disc with $f_{\rm thick}\sim16\%$; and (6) a dynamically hot, spatially diffuse stellar halo with $f_{\rm halo}\sim5\%$. The nuclear disc, bar, and thin disc are metal-rich ($[Z/\rm H]\gtrsim0$), $α$-poor ($\rm[Mg/Fe]\lesssim0.2$), and old ($\sim13\rm\,Gyr$), corresponding to in situ formation in the early Universe. The bulge, thick disc, and stellar halo are metal-poor ($[Z/\rm H]\lesssim0$), $α$-rich ($\rm[Mg/Fe]\gtrsim0.2$), and younger than or comparable in age to the in situ components, suggesting ex situ formation via minor mergers. Further analysis of stellar population gradients reveals that the thick disc and stellar halo, with their flat metallicity and [Mg/Fe] gradients, are likely dominated by a similar ex situ population. In contrast, the bulge exhibits a negative metallicity gradient ($\nabla[Z/\rm H]_{bulge}<0$), which might originate from either predominantly ex situ stars or a mixture of in situ and ex situ stars; its ex situ fraction cannot be quantified with the current data. Our modelling also reveals a slow bar ($\mathcal{R}=2.40_{-0.27}^{+0.54}$), with a bar pattern speed of $\rmΩ_p=34_{-7}^{+4}\,km\,s^{-1}\,kpc^{-1}$, a bar length of $R_{\rm bar}=2.24_{-0.22}^{+0.43}\rm\,kpc$, and a corotation radius of $R_{\rm CR}=5.38_{-0.28}^{+1.59}\rm\,kpc$, consistent with its ancient formation time.

astro-ph.GA↗
arXiv2026

A Deep Look at the Ultra-Faint Milky Way Satellite Virgo III with Rubin Observatory Data Preview 2

We analyze the ultra-faint Milky Way satellite Virgo III using data from the Vera C. Rubin Observatory Data Preview 2 (DP2). Virgo III was observed in the Rubin "Cosmic Treasure Chest" (M49) First Look field, which contains 924 visits in the u,g,r,i bands comprising ~10.5hrs of exposure time with LSSTCam. These data are considerably deeper than the majority of DP2, with a $5σ$ limiting magnitude that approaches the expected 10-year depth of LSST (~25.2-26.5mag, depending on band). We report the morphological and stellar population parameters of Virgo III measured with the maximum-likelihood-based package ugali. The depth of the Rubin imaging yields more than a factor of four increase in the number of candidate member stars ($N_* = 114^{+11}_{-11}$) relative to the Virgo III discovery results ($N_* = 25^{+5}_{-4}$), enabling significantly more precise morphological constraints. Our best-fit parameters broadly agree with previous measurements, further confirming that Virgo III has properties that are consistent with an ultra-faint dwarf galaxy ($M_V = -2.72^{+0.49}_{-0.70}$; $r_{1/2} = 53^{+10}_{-8}$) located at a heliocentric distance of $D_\odot = 151^{+8}_{-8}$. We also demonstrate that the depth and photometric quality of the DP2 data are sufficient to separate metal-poor and metal-rich stars in color-color space. We further present period estimates for the three known RR Lyrae member stars derived from the DP2 forced photometry; we use theoretical Period-Luminosity-Metallicity (PLZ) and Period-Wesenheit-Metallicity (PWZ) relations to obtain independent distance estimates. We find that our period and distance estimates are broadly consistent with previous measurements for these RR Lyrae. These results demonstrate the power of LSST data for the discovery and characterization of ultra-faint dwarf galaxies and motivate future searches for new satellites across the southern sky.

astro-ph.GA↗