It is important to point out that our simulation was stopped at 3 Gyr, leaving more than 10 Gyr of gas evolution in the Ursa Minor unexplored. In fact, SNe-Ia events must occur after 3 Gyr, but at a lower rate (≲15 SNe Myr−1; Lanfranchi & Matteucci 2004, 2007). Thus, SNe Ia could keep the galactic wind active and remove an additional amount of gas from the Little Dipper. We made a simple estimate of the mass fraction of gas in galactocentric radii of 600 and 950 pc after 13 gyr of development. It was prepared from the extrapolation of an exponential adjustment of the instantaneous mass fraction as a function of instantaneous SNe rates of type Ia from the chemical evolution model of Lanfranchi & Matteucci (2004) between 1.8 and 3 Gyr. We obtained mass fractions of ∼0.37 and ∼0.22 in 950 pc and 600 pc, respectively. This represents a decrease of less than 2% compared to the respective values at 3 gyr, which is not enough to significantly reduce the remaining gas mass at the end of our current simulation. A puzzling feature of all spheroidal dpygmy galaxies (dSph) in the Local Group is the absence of neutral gas, at least in their central regions (Mateo 1998; Grcevich & Putman 2009 and references therein). Ursa Minor, like all other classical dSphs, is an example of a galaxy that has no gaseous component. Grcevich and Putman (2009) studied the environment and H i content of all local dwarf galaxies using HIPASS (Barnes et al. 2001) and LAB (Kalberla et al. 2005) data. They detected no signs of neutral gas in Ursa Minor, confirming the results of previous work (Knapp et al., 1978; Willman et al., 2005; Belokurov et al., 2007; Simon and Geha, 2007).
These authors did not reach a clear conclusion as to the dominant physical process that would be responsible for the disappearance of interstellar gas, although external mechanisms such as dynamic pressure and tidal stripping are preferred (see also Emerick et al. 2016 and references therein). On the other hand, internal processes such as galactic winds triggered by supernova explosions (SNe) must also be taken into account. Programa: Situación del parque inmobiliario – Novedades CTE en Rehabilitación – Soluciones constructivas – Instrumentos From a reanalysis of data from the Sloan Digital Sky Survey Data Release 8, Geha et al. (2012) found no star-forming dwarf galaxies with stellar masses between 107 and 109 M⊙ at distances greater than about 1.5 Mpc from the (massive) host galaxy. They also showed that the proportion of erased dwarf galaxies in star formation increases sharply with decreasing distance from a massive host galaxy (see Figure 6). These results suggest that these field dwarf galaxies could not stop their star formation on their own (in the sense of passive evolution that converts gas into stars), and require an additional mechanism (probably Ram pressure and tidal stripping effects) to remove the gas. In this context, Ursa Minor can now be classified as an unerased galaxy because it is located at a heliocentric distance of about 64 kpc (Irwin & Hatzidimitriou 1995), it does not currently form stars (e.g. Dolphin 2002; Lanfranchi and Matteucci, 2004), and it is a low-gas system (e.g., Grcevich and Putman, 2009; Spekkens et al., 2014). However, it is important to note that Ursa Minor has a derived stellar mass of about 8 × 105 M⊙ (Dekel & Woo 2003; Orban et al. 2008), about an order of magnitude lower than the stellar mass range, in which the results of Geha et al.
(2012) are strictly valid. where is the unit position vector. This initial accumulation involves an initial gas mass of about 2.94 × 108 M⊙ and a halo DM mass of 1.51 × 109 M⊙. Now the company wants to increase this training offer, which does not forget the training and qualification of its own employees. 1 Nucleus of Theoretical Astrophysics, Universidade Cruzeiro do Sul, R. Galvão Bueno 868, Liberdade, 01506-000, São Paulo, SP, Brazil; firstname.lastname@example.org. URSA is a company dedicated to the production and marketing of thermal and acoustic insulation materials focused on the sustainability and energy efficiency of buildings. It has a large commercial presence in Spain and Europe thanks to its 13 production plants strategically located throughout the European continent.
The resulting gas mass, which is greater than the value derived from the observations, is similar to those described by Caproni et al. (2015), but using constant SN rates over time (type II). They highlighted the possibility of an additional external mechanism to reconcile the final gas mass derived from their hydrodynamic simulations, such as tidal pickling (e.g., Blitz and Robishaw, 2000; Read et al., 2006b) and pressure stripping of cylinders (e.g., Gunn and Gott, 1972; Mayer et al., 2006; McConnachie et al., 2007). Another possibility is whether cosmic rays or radiative heating from the local ISM increase the temperature of the gas. Galactic thermal winds have been shown to be responsible for relatively large mass loss rates, although lower than those found by SNe feedback (Falceta-Gonçalves 2013).