Evolution of Ionized Interstellar Medium across Cosmic Time
Fuyan Bian, European Southern Observatory
The ionized interstellar medium (ISM) provides essential information on the star-forming environments, metal enrichment, and underlying ionizing radiation field in galaxies. It is crucial to understand how the ionized ISM evolves with Cosmic time. In this talk, I will present a sample of local galaxies that closely resemble the properties of high-redshift galaxies at high redshift. These local analogs of high-redshift galaxies provide a unique local laboratory to study high-redshift galaxies. I will discuss how to use these analogs to improve our understanding of the high-redshift metallicity empirical calibrations and physical mechanism(s) to drive the evolution of optical diagnostics lines from high redshift to low redshift.
The role if the intergalactic medium in the baryon cycle
Valentina D’Odorico, INAF Osservatorio Astronomico di Trieste
The intergalactic medium (IGM) plays a relevant role in galaxy evolution being the reservoir of gas for star formation and, at the same time, collecting the products of star formation ejected from galaxies. The IGM is studied mainly in absorption, in the spectra of high redshift bright objects. In this talk, I will briefly review the recent development in the study of the IGM, in particular the determination of its metal enrichment, in the context of the baryon cycle in galaxies. I will focus my presentation on the high redshift regime, reaching the epoch of reionization, where strong constraints are set to the models of galaxy evolution.
Planet formation in protoplanetary discs around young stars
Anders Johansen (Lund University, Sweden)
Planets form in protoplanetary discs around young stars as dust and ice particles collide to form larger and larger bodies. I will present a coherent theory framework for the formation of planetary systems. Dust grows to pebbles by coagulation and deposition of volatile ices, but the continued growth to planetesimals is hampered by the poor sticking of mm-cm-sized pebbles. Planetesimals can nevertheless form by gravitational collapse of pebble clumps concentrated in the turbulent gas through the streaming instability. The subsequent growth initially occurs by planetesimal-planetesimal collisions, but the accretion rate of pebbles dominates the growth from 1000-km-sized protoplanets to form the solid cores of gas giants, ice giants and super-Earths. The high growth rates by pebble accretion allow planetary cores to start their growth in much more distant positions than their final orbits. The giant planets orbiting our Sun and other stars can therefore be formed in consistency with planetary migration.
Enhancing Time-Dependent Solar Wind Models to Constrain Effects on Non-Magnetized Planetary Atmospherese
Sarah Kovac, NMSU
H-Band Spectroscopy of Exotic, Massive Stars
Drew Chojnowski, NMSU
We report on spectroscopy of exotic B-type emission line (Be) stars and chemically peculiar (CP) stars in the near-infrared (NIR) H-band, using data provided by the Apache Point Observatory Galactic Evolution Experiment, one of the sub-surveys of the Sloan Digital Sky Survey (SDSS). Between 2011-2020, SDSS/APOGEE has observed more than a million stars in the Milky Way Galaxy (MW), with roughly 10% of the targets being hot, blue stars that serve as telluric absorption standard stars (TSS). The TSS are selected mostly on the basis of having blue raw J-K color indices with no preference for any particular spectral type that might be known from optical spectroscopy. This targeting strategy has led to the TSS being a mixed bag, with those observed in the MW Halo typically being F-type stars that are only slightly more massive than the Sun, and with those observed in the MW Disk and Bulge being OBA-type stars of a few up to 20 times the mass of the Sun. While the vast majority of the TSS are superficially normal main sequence stars, the inclusion of large numbers of Be and CP stars has serendipitously resulted in the largest ever homogeneous spectroscopic surveys of these stellar classes, both of which present observational anomalies that remain very poorly understand despite more than a hundred years of research. Prior to SDSS/APOGEE, the H-band spectra of Be and CP stars had only been discussed in a handful of studies, all of which used small numbers of spectra of considerably lower resolution than the R=22,500 of the APOGEE instruments. The material presented in this thesis therefore represents the first ever detailed studies of Be and CP stars in the H-band, while also greatly expanding the known samples through discovery of many hundreds of new examples.