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The quenching of cluster satellite galaxies is inextricably linked to the suppression of their cold interstellar medium (ISM) by environmental mechanisms. While the removal of neutral atomic hydrogen (H i) at large radii is well studied, how the environment impacts the remaining gas in the centres of galaxies, which are dominated by molecular gas, is less clear. Using new observations from the Virgo Environment traced in CO survey (VERTICO) and archival H i data, we study the H i and molecular gas within the optical discs of Virgo cluster galaxies on 1.2-kpc scales with spatially resolved scaling relations between stellar (
$\Sigma_{\star}$), H i (
$\Sigma_{\text{H}\,{\small\text{I}}}$), and molecular gas (
$\Sigma_{\text{mol}}$) surface densities. Adopting H i deficiency as a measure of environmental impact, we find evidence that, in addition to removing the H i at large radii, the cluster processes also lower the average 
$\Sigma_{\text{H}\,{\small\text{I}}}$ of the remaining gas even in the central 
$1.2\,$kpc. The impact on molecular gas is comparatively weaker than on the H i, and we show that the lower 
$\Sigma_{\text{mol}}$ gas is removed first. In the most H i-deficient galaxies, however, we find evidence that environmental processes reduce the typical 
$\Sigma_{\text{mol}}$ of the remaining gas by nearly a factor of 3. We find no evidence for environment-driven elevation of 
$\Sigma_{\text{H}\,{\small\text{I}}}$ or 
$\Sigma_{\text{mol}}$ in H i-deficient galaxies. Using the ratio of 
$\Sigma_{\text{mol}}$-to-
$\Sigma_{\text{H}\,{\small\text{I}}}$ in individual regions, we show that changes in the ISM physical conditions, estimated using the total gas surface density and midplane hydrostatic pressure, cannot explain the observed reduction in molecular gas content. Instead, we suggest that direct stripping of the molecular gas is required to explain our results.
Close galaxy flybys, interactions during which two galaxies inter-penetrate, are frequent and can significantly affect the evolution of individual galaxies. Equal-mass flybys are extremely rare and almost exclusively distant, while frequent flybys have mass ratios 
$q=0.1$ or lower, with a secondary galaxy penetrating deep into the primary. This can result in comparable strengths of interaction between the two classes of flybys and lead to essentially the same effects. To demonstrate this, emphasise and explore the role of the impact parameter further, we performed a series of N-body simulations of typical flybys with varying relative impact parameters 
$b/R_{\mathrm{vir},1}$ ranging from 
$0.114$ to 
$0.272$ of the virial radius of the primary galaxy. Two-armed spirals form during flybys, with radii of origin correlated with the impact parameter and strengths well approximated with an inverted S-curve. The impact parameter does not affect the shape of induced spirals, and the lifetimes of a distinguished spiral structure appear to be constant, 
$T_\mathrm{LF} \sim 2$ Gyr. Bars, with strengths anti-correlated with the impact parameter, form after the encounter is over in simulations with 
$b/R_{\mathrm{vir},1} \leq 0.178$ and interaction strengths 
$S\geq0.076$, but they are short-lived except for the stronger interactions with 
$S\geq0.129$. We showcase an occurrence of multiple structures (ring-like, double bar) that survives for an exceptionally long time in one of the simulations. Effects on the pre-existing bar instability, that develops much later, are diverse: from an acceleration of bar formation, little to no effect, to even bar suppression. There is no uniform correlation between these effects and the impact parameter, as they are secondary effects, happening later in a post-flyby stage. Classical bulges are resilient to flyby interactions, while dark matter halos can significantly spin up in the amount anti-correlated with the impact parameter. There is an offset angle between the angular momentum vector of the dark matter halo and that of a disc, and it correlates linearly with the impact parameter. Thus, flybys remain an important pathway for structural evolution within galaxies in the local Universe.
In order to gain more information on the 236 M dwarfs identified in the First Byurakan Survey (FBS) low-resolution (lr) spectroscopic database, Gaia EDR3 high-accuracy astrometric and photometric data and Transiting Exoplanet Survey Satellite (TESS) data are used to characterise these M dwarfs and their possible multiplicity. Among the sample of 236 relatively bright 
$(7.3 < K_S < 14.4)$ M dwarfs, 176 are new discoveries. The Gaia EDR3 G broadband magnitudes are in the range 
$11.3 < G < 17.1$. New distance information based on the EDR3 parallaxes are used to estimate the G-band absolute magnitudes. Nine FBS M dwarfs out of 176 newly discovered lie within 25 pc of the Sun. The FBS 0909-082 is the most distant 
$(r=780$ pc) M dwarf of the analysed sample, with a G-band absolute magnitude 
$M(G) = 9.18$, 
$M = 0.59$ M
$_{\odot}$, 
$L = 0.13597$ L
$_{\odot}$, and 
$T_{eff}$ = 3844 K; it can be classified as M1 - M2 subtype dwarf. The nearest is FBS 0250+167, a M7 subtype dwarf located at 3.83 pc from the Sun with a very high proper motion (5.13 arcsec yr
$^{-1}$). The TESS estimated masses lie in the range 0.095 (
$\pm$0.02) M
$_{\odot}\leq$ 
$M\leq$ 0.7 (
$\pm$ 0.1) M
$_{\odot}$ and 
$T_{eff}$ in the range 4000 K < 
$T_{eff}$ < 2790 K. We analyse colour-colour and colour-absolute magnitude diagram (CaMD) diagrams for the M dwarfs. Results suggest that 27 FBS M dwarfs are double or multiple systems. The observed spectral energy distribution (SED) for some of the M dwarfs can be used to classify potential infrared excess. Using TESS light curves, flares are detected for some FBS M dwarfs. Finally, for early and late sub-classes of the M dwarfs, the detection range for survey is estimated for the first time.
A new determination of the temperature of the intergalactic medium (IGM) over 
$3.9 \leq z \leq 4.3$ is presented. We applied the curvature method on a sample of 10 high-resolution quasar spectra from the Ultraviolet and Visual Echelle Spectrograph on the VLT/ESO. We measured the temperature at mean density by determining the temperature at the characteristic overdensity, which is tight function of the absolute curvature irrespective of 
$\unicode{x03B3}$. Under the assumption of fiducial value of 
$\unicode{x03B3} = 1.4$, we determined the values of temperatures at mean density 
$T_{0} = 7893^{+1417}_{-1226}$ K and 
$T_{0} = 8153^{+1224}_{-993}$ K for redshift range of 
$3.9 \leq z \leq 4.1$ and 
$4.1 \leq z \leq 4.3$, respectively. Even though the results show no strong temperature evolution over the studied redshift range, our measurements are consistent with an IGM thermal history that includes a contribution from He ii reionisation.
