ELFT HÍRADÓ

[vidakris AT konkoly.hu]

Szemináriumi meghívó / Invitation to a seminar
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CSFK CSI SZEMINÁRIUM / KONKOLY OBSERVATORY SEMINAR

Date: Mar 14 (Thursday) 14:00


Hedieh Abdollahi (Institute for Research in Fundamental Sciences (IPM), Iran):
Star Formation History and Dust Production Rate in And IX, the Closest 
Satellite of the Andromeda Galaxy


We present a photometric study of the resolved stellar populations in And IX, 
the closest satellite to M31, a metal-poor and low-mass dwarf spheroidal 
galaxy. We estimate a distance modulus of 24.56 mag (∼ 816.58 kpc) based on 
the tip of the red giant branch (TRGB). By probing the variability of 
asymptotic giant branch stars (AGB), we study the star formation history of 
And IX. We identified 50 long period variables (LPVs) in And IX using the 
Isaac Newton Telescope (INT) in two filters, Sloan i' and Harris V. In this 
study, we selected LPVs within two half-light radii (∼ 5 arcmin) with 
amplitudes in the range of 0.20 to 2.20 mag. It is found that the peak of 
star formation reached ∼ 8.2 ± 3.1 × 10^−4 M⊙/yr at ≈ 6 Gyr ago. Our findings 
suggest an outside-in galaxy formation scenario for And IX with a quenching 
occurring 3.65 Gyr ago with the SFR in the order of 2.0 × 10^−4 M⊙/yr at 
redshift < 0.5. We calculate the total stellar mass by integrating the star 
formation
  rate (SFR) within two half-light radii to be ∼ 3.0 × 10^5 M⊙. By employing 
the spectral energy distribution (SED) fitting for observed LPVs in And IX, 
we evaluate the mass-loss rate in the range of 10^−7 to 10^−5 M⊙/yr. Finally, 
we show that the total mass deposition to the interstellar medium (ISM) is ∼ 
2.4 × 10^−4 M⊙/yr from the C- and O-rich type of dust-enshrouded LPVs. The 
ratio of the total mass returned to the ISM by LPVs to the total stellar mass 
is ∼ 8.0 × 10^−10 1/yr, and so at this rate, it would take ∼ 1 Gyr to 
reproduce this galaxy.

The seminar will be held live in the Detre hall with audience, but also 
streamed online via Zoom. If you are unable to attend the presentation in 
person, you can join us via this link
https://us06web.zoom.us/j/82806911982?pwd=SVZpT0syQ1J6dHBvSkF4N2dXNEQ0dz09
or the meeting ID: 828 0691 1982 and passcode: 206265



Everyone is welcome!

Krisztián Vida, Ramon Brasser
organizers
https://konkoly.hu/k-szeminariumok