The UK Infrared Telescope M33 monitoring project. III. Feedback from dusty stellar winds in the central square kiloparsec

We have conducted a near-infrared monitoring campaign at the UK InfraRed Telescope (UKIRT), of the Local Group spiral galaxy M33 (Triangulum). The main aim was to identify stars in the very final stage of their evolution, and for which the luminosity is more directly related to the birth mass than the more numerous less-evolved giant stars that continue to increase in luminosity. In this third paper of the series, we measure the dust production and rates of mass loss by the pulsating Asymptotic Giant Branch (AGB) stars and red supergiants. To this aim, we combined our time-averaged near-IR photometry with the multi-epoch mid-IR photometry obtained with the Spitzer Space Telescope. The mass-loss rates are seen to increase with increasing strength of pulsation and with increasing bolometric luminosity. Low-mass stars lose most of their mass through stellar winds, but even super-AGB stars and red supergiants lose $\sim40$% of their mass via a dusty stellar wind. More than three-quarters of the dust return is oxygenous. We construct a 2-D map of the mass-return rate, showing a radial decline but also local enhancements due to agglomerations of massive stars. We estimate a total mass-loss rate of 0.004--0.005 M$_\odot$ yr$^{-1}$ kpc$^{-2}$, increasing to $\sim0.006$ M$_\odot$ yr$^{-1}$ kpc$^{-2}$ when accounting for eruptive mass loss (e.g., supernov{\ae}); comparing this to the current star formation rate of $\sim0.03$ M$_\odot$ yr$^{-1}$ kpc$^{-2}$ we conclude that star formation in the central region of M\,33 can only be sustained if gas is accreted from further out in the disc or from circum-galactic regions.Comment: Accepted for publication in MNRA

The Isaac Newton Telescope Monitoring Survey of Local Group Dwarf Galaxies. VI. The Star Formation History and Dust Production in Andromeda IX

We present a photometric study of the resolved stellar populations in Andromeda IX (And IX), the closest satellite to M31, a metal-poor and low-mass dwarf spheroidal galaxy. We estimate a distance modulus of $24.56^{+0.05}_{-0.15}$ mag based on the tip of the red giant branch. By probing the variability of asymptotic giant branch stars, we study the star formation history of And IX. We identified 50 long-period variables (LPVs) in And IX using the Isaac Newton Telescope in two filters, the Sloan $i'$ and Harris $V$. In this study, we selected LPVs within two half-light radii with amplitudes in the range of 0.2–2.20 mag. It is found that the peak of star formation reaches ${\sim}8.2 {\pm} 3.1 {\times} 10{^-4}M_{\odot} yr^{-1}$ at ≈6 Gyr ago. Our findings suggest an outside-in galaxy formation scenario for And IX with a quenching occurring $3.65^{+1.52}_{-0.13}$ Gyr ago with a star formation rate (SFR) in the order of $2.0 {\times} 10^{-4}M_{\odot} yr^{-1}$ at redshift <0.5. We calculate the total stellar mass by integrating the SFR within two half-light radii ${\sim}3.0 {\times} 10^{5}M_{\odot}$. By employing spectral energy distribution fitting for the observed LPVs in And IX, we evaluate a mass-loss rate in the range of $10^{-7} ≤ M ≤ 10^{-5} M_{\odot} yr^{-1}$. Finally, we show that the total mass deposition to the interstellar medium (ISM) is ${\sim}2.4 {\times} 10^{-4} M_{\odot} yr^{-1}$ from the C- and O-rich types of dust-enshrouded LPVs. The ratio of the total mass returned to the ISM by LPVs to the total stellar mass is ${\sim}8.0 {\times} 10^{-10} yr^{-1}$, and so at this rate it would take ∼1 Gyr to reproduce this galaxy

The UK Infrared Telescope M33 monitoring project. II. The star formation history in the central square kiloparsec

We have conducted a near-infrared monitoring campaign at the UK InfraRed Telescope (UKIRT), of the Local Group spiral galaxy M33 (Triangulum). The main aim was to identify stars in the very final stage of their evolution, and for which the luminosity is more directly related to the birth mass than the more numerous less-evolved giant stars that continue to increase in luminosity. In this second paper of the series, we construct the birth mass function and hence derive the star formation history. The star formation rate has varied between ~0.002 and 0.007 M$_\odot$ yr^-1 kpc^-2. We give evidence of two epochs of a star formation rate enhanced by a factor of a few -- one that happened \geq 6 Gyr ago and produced \geq 80% of the total mass in stars, and one around 250 Myr ago that lasted ~ 200 Myr and formed \leq 6% of the mass in stars. We construct radial and azimuthal distributions in the image plane and in the galaxy plane for populations associated with old first-ascent red giant branch (RGB) stars, intermediate-age Asymptotic Giant Branch (AGB) stars and young (massive) blue and red supergiants. We find that the RGB stars follow a spheroidal distribution, while younger stars follow a flat-disc distribution. The intermediate-age population displays signs of a pseudo-bulge or possibly a bar. The inner spiral arm pattern as recorded in mid-19^th-century drawings is confirmed. We interpret our findings as evidence for an old, pressure-supported component and a younger disc formed 6 Gyr ago, with an accretion event occurring 250 Myr ago giving rise to the compact nucleus in M33. Our study provides support for recent Padova stellar evolution models except that super-AGB stars likely reach low temperatures and thus high mass-loss rates, supporting the super-AGB nature of the progenitors of dust-enshrouded supernovae such as SN2008S.Comment: Accepted for publication in MNRA

Factors affecting the development of Astro-Tourism Destinations

This study aims to find the Astro-Tourism potentials and to identify the strategies required for development of this kind of tourism in Iran. The research method which is used in this survey is different regarding different aims we are looking for. It is functional according to the purpose, field study according to the control degree and measurement and descriptive according to the data collecting strategy. Therefore, the method is descriptive-analytic which the required data has been collected and analyzed by distributing the questionnaire and observation. Subsequently, inferential statistics including factor analysis has been used to achieve the aim of this research. The samples of this research were 206 persons were choices from amateurs, professionals and especially tourism experts in sky/star observation tours that were selected by Judgmental sampling. The data and methods of achieving descriptive and inferential statistics, including factor analysis using SPSS software were used. In this study, the questionnaire was composed of total of 35 variables. While considering these variables and ranking them, 7 factors identified by factor analysis. These factors involve 5/00 development infrastructure, 4/18 professional astronomy infrastructure, 3/88 ecological and geographical area/zone, 2/61 physical infrastructure of tourism, 2/43 safety and security, 2/00 preparing particular observing situation, 1/97 recreational tourism infrastructur