2022.11.17 - Sebastian Sanchez
Channel: Coloquio IRyA
Date: 30/11/2022

Speaker info: Dr. Sebastian F. Sanchez Sanchez, Head of the Observational Astronomy Department, Investigador Titular C, Instituto de Astronomía, UNAM

Title: Seeking habitable regions in the nearby Universe
Abstract:
We only have one single example of life in the Universe, which 
introduces a strong bias in our perception of which could be the 
conditions required for its existence. Despite this bias, we can fairly 
assume that any habitable earth-like planet should be formed in an 
environment rather similar to the solar neighborhood in terms of 
chemical composition, distribution of stellar populations, and in 
general star-formation and chemical enrichment history. Under this 
assumption, and considering that all those properties are deeply coded 
in the Solar Neighborhood spectrum, we seek for Solar Neighborhood 
Analogs (SNAs) in the nearby Universe, constraining the probability to 
find habitable regions.

We introduce a novel nonparametric method
 to find these SNAs using extragalactic integral field spectroscopic 
surveys. The main ansatz is that the physical properties of the solar 
neighborhood (SN) should be encoded in its optical stellar spectrum. We 
assume that our best estimate of such a spectrum is the one extracted 
from the analysis performed by the Code for Stellar properties Heuristic
 Assignment (CoSHA) from the MaStar stellar library. It follows that 
finding SNAs in other galaxies consist in matching, in a χ2 sense, the 
SN reference spectrum across the optical extent of the observed 
galaxies. We applied this procedure to a selection of CALIFA galaxies, 
by requiring a close to face-on projection, relative isolation, and 
non-active galactic nucleus. We explore how the local and global 
properties of the SNAs (stellar age, metallicity, dust extinction, 
mass-to-light ratio, stellar surface mass density, star-formation 
density, and galactocentric distance) and their corresponding host 
galaxies (morphological type, total stellar mass, star-formation rate, 
and effective radius) compared with those of the SN and the Milky Way 
(MW).  We find that SNAs are located preferentially in S(B)a-S(B)c 
galaxies, in a ring-like structure, which radii seem to scale with the 
galaxy size. Despite the known sources of systematics and errors, most 
properties present a considerable agreement with the literature on the 
SN. We conclude that the solar neighborhood is relatively common in our 
sample of SNAs. Our results warrant a systematic exploration of 
correlations among the physical properties of the SNAs and their host 
galaxies. We reckon that our method should inform current models of the 
galactic habitable zone in our MW and other galaxies.