We explore the chemodynamical properties of a sample of barred galaxies in the Auriga magnetohydrodynamical cosmological zoom-in simulations, which form boxy/peanut (b/p) bulges, and compare these to the Milky Way (MW). We show that the Auriga galaxies which best reproduce the chemodynamical properties of stellar populations in the MW bulge have quiescent merger histories since redshift z ∼ 3.5: their last major merger occurs at $t_{\rm lookback}\gt 12\, \rm Gyr$, while subsequent mergers have a stellar mass ratio of ≤1:20, suggesting an upper limit of a few per cent for the mass ratio of the recently proposed Gaia Sausage/Enceladus merger. These Auriga MW-analogues have a negligible fraction of ex-situ stars in the b/p region ($\lt 1{{\ \rm per\ cent}}$), with flattened, thick disc-like metal-poor stellar populations. The average fraction of ex-situ stars in the central regions of all Auriga galaxies with b/p’s is 3 per cent – significantly lower than in those which do not host a b/p or a bar. While the central regions of these barred galaxies contain the oldest populations, they also have stars younger than 5 Gyr (>30 per cent) and exhibit X-shaped age and abundance distributions. Examining the discs in our sample, we find that in some cases a star-forming ring forms around the bar, which alters the metallicity of the inner regions of the galaxy. Further out in the disc, bar-induced resonances lead to metal-rich ridges in the Vϕ − r plane – the longest of which is due to the Outer Lindblad Resonance. Our results suggest the Milky Way has an uncommonly quiet merger history, which leads to an essentially in-situ bulge, and highlight the significant effects the bar can have on the surrounding disc.

We present Very Large Array (VLA) and Atacama Large Millimeter/submillimeter Array (ALMA) observations of the close (0.″3 = 90 au separation) protobinary system SVS 13. We detect two small circumstellar disks (radii ∼12 and ∼9 au in dust, and ∼30 au in gas) with masses of ∼0.004–0.009 M ☉ for VLA 4A (the western component) and ∼0.009–0.030 M ☉ for VLA 4B (the eastern component). A circumbinary disk with prominent spiral arms extending ∼500 au and a mass of ∼0.052 M ☉ appears to be in the earliest stages of formation. The dust emission is more compact and with a very high optical depth toward VLA 4B, while toward VLA 4A the dust column density is lower, allowing the detection of stronger molecular transitions. We infer rotational temperatures of ∼140 K, on scales of ∼30 au, across the whole source, and a rich chemistry. Molecular transitions typical of hot corinos are detected toward both protostars, being stronger toward VLA 4A, with several ethylene glycol transitions detected only toward this source. There are clear velocity gradients, which we interpret in terms of infall plus rotation of the circumbinary disk, and pure rotation of the circumstellar disk of VLA 4A. We measured orbital proper motions and determined a total stellar mass of 1 M ☉. From the molecular kinematics, we infer the geometry and orientation of the system, and stellar masses of ∼0.26 M ☉ for VLA 4A and ∼0.60 M ☉ for VLA 4B.

In this work we analyse the structural and photometric properties of 21 barred simulated galaxies from the Auriga Project. These consist of Milky Way-mass magnetohydrodynamical simulations in a ΛCDM cosmological context. In order to compare with observations, we generate synthetic SDSS-like broad-band images from the numerical data at z = 0 with different inclinations (from face-on to edge-on). Ellipse fits are used to determine the bar lengths, and 2D bulge/disc/bar decompositions with galfit are also performed, modelling the bar component with the modified Ferrer profile. We find a wide range of bar sizes and luminosities in the sample, and their structural parameters are in good agreement with the observations. All bulges present low Sérsic indexes, and are classified as pseudobulges. In regard to the discs, the same breaks in the surface brightness profiles observed in real galaxies are found, and the radii at which these take place are in agreement with the observations. Also, from edge-on unsharp-masked images at z = 0, boxy or peanut-shaped (B/P) structures are clearly identified in the inner part of 4 bars, and also 2 more bars are found in buckling phase. The sizes of the B/P match fairly well with those obtained from observations. We thus conclude that the observed photometric and structural properties of galaxies with bars, which are the main drivers of secular evolution, can be developed in present state-of-the-art ΛCDM cosmological simulations.

<p>The early stages of the formation of binary stellar systems are still rather poorly understood observationally, which contrasts with some significant recent improvements in numerical simulations. We present a comprehensive study with the VLA and ALMA of the close (separation = 90 au) proto-binary system SVS 13. Our very high sensitivity and spatial resolution observations trace the dust as well as the ionized and molecular gas in this system, reaching scales as small as ~10 au. We infer the orbital motion and masses of the two protostars. We image two circumstellar disks and a still-forming circumbinary disk with prominent spiral arms extending ~500 au. We study the 3D kinematics of the system and measure the physical properties of the disks. We also find evidence for variation of chemical properties on scales of a few tens of au. Finally, we will discuss on how the properties of the SVS 13 system compare with those of a few other protobinary systems that have been observed with a similar degree of detail, and with the predictions of numerical simulations. This kind of information provides some clues on the final configuration of planetary systems in binary systems.</p><p><img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.c8ee04a7c48268209682561/sdaolpUECMynit/2202CSPE&app=m&a=0&c=27e8eacc3cd75b4b612009405aa39837&ct=x&pn=gnp.elif&d=1" alt="" width="702" height="670"></p><p>ALMA observation of dust in the disks around SVS 13 (credit: A.K. Diaz-Rodriguez, G. Anglada 2022).</p><p><img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.5b320fc7c48261709682561/sdaolpUECMynit/2202CSPE&app=m&a=0&c=a0388163eaebf96cf38bbbbd829d450d&ct=x&pn=gnp.elif&d=1" alt="" width="698" height="676"></p><p> </p><p>Cartoon model of the system. The red-blue colours indicate the motion of the gas. Red – away from us, blue – towards us. The peculiar yin-yang shape results from the combination of infalling and rotation motions (credit: A. K. Diaz-Rodriguez et al. 2022).</p>