Galactic center G objects as dust-enshrouded stars near the supermassive black hole

In this talk, I revisited the model of a dust-enshrouded star orbiting a low-luminosity galactic nucleus (Zajacek et al., 2014, 2016, 2017). Although it is quite challenging for dust to survive in hot X-ray-emitting plasma surrounding supermassive black holes (SMBHs), now we have an observational evidence that compact dusty objects or G objects can approach the SMBH in the Galactic center (Sgr A*) on the scale of a few 1000 gravitational radii. Since there are about ten G objects in the Galactic center, it is more likely that they are dust-enshrouded stars whose gaseous-dusty envelopes are stable within the corresponding tidal (Hill) radii of the order of a few astronomical units. Such a length-scale is consistent with their infrared broad-band spectral energy distributions. Broad emission lines, such as in particular Br-gamma recombination line, can be interpreted to arise within the accretion stream from the circumstellar envelopes forming a compact disc that is truncated by the stellar magnetic field. Alternatively, they could also be associated with circumstellar accretiondisc outflows. In comparison with the line origin in the photoionized envelopes that can generally be tidally perturbed, the scenario involving the circumstellar accretion-disc inflow or outflow can ensure that the line luminosity is rather stable. I speculate about the origin of dust-enshrouded stars (young stellar objects or binary mergers) as well as prospects to detect their signs around other low-luminosity galactic nuclei. Current status of the H_0 and growth tensions: theoretical models and model-independent