In order to understand the origin of the decreased star formation rate (SFR) efficiency of neutral atomic hydrogen gas measured in Damped Lyα Systems (DLAs) at z ~ 3, we measure the SFR efficiency of atomic gas at z ~ 1, z ~ 2, and z ~ 3 around star-forming galaxies. We create galaxy stacks in these three redshift bins, and measure the SFR efficiency by combining DLA absorber statistics with the observed rest-frame UV emission in the galaxies’ outskirts. We find that the SFR efficiency of Hi gas is ~ 3% of that predicted by the KS relation. We find no significant evolution in the SFR efficiency with redshift, although simulations and models predict a decreasing SFR efficiency with decreasing metallicity and thus with increasing redshift. We discuss possible explanations for this decreased efficiency without an evolution with redshift.

We summarize our analysis of singly-ionized elements of astrophysical interest.

We report new measurements of atomic data for the neutral, singly and doubly ionised iron group element spectra for modern astrophysics applications.

We have assembled a new sample of some of the most FIR-luminous galaxies in the Universe and have imaged them in 1.1 mm dust emission and measured their redshifts 1 < z < 4 via CO emission lines using the 32-m Large Millimeter Telescope / Gran Telescopio Milimétrico (LMT/GTM). Our sample of 31 submm galaxies (SMGs), culled from the Planck and Herschel all-sky surveys, includes 14 of the 21 most luminous galaxies known, with LFIR > 1014L⊙ and SFR > 104M⊙/yr. These extreme inferred luminosities – and multiple / extended 1.1 mm images – imply that most or all are strongly gravitationally lensed, with typical magnification μ ~ 10 × . The gravitational lensing provides two significant benefits: (1) it boosts the S/N, and (2) it allows investigation of star formation and gas processes on sub-kpc scales.

Direct ultraviolet imaging and spectroscopy of Alpha Orionis (Betelgeuse) reveals variable chromospheric structures and mass motions. Spectroscopy also demonstrates the changes of wind opacity, speeds, and mass loss in luminous stars. Cool stars have complex chromospheres that need to be considered in construction of stellar atmospheric models and subsequent spectral analyses.

We present an overview of the advances made during the past 15 years by the Atomic Physics and Astrophysics Group of Mons University regarding the analysis of the spectra, the transition probabilities, and the radiative lifetimes in heavy elements. More precisely, this review is focused on neutral and lowly ionized atoms belonging to the lanthanide group, the fifth row, and the sixth row of the periodic table (Z = 37–86), for which a very large amount of new data has been obtained.

Red Supergiants (RSGs) have for decades been assumed to be the progenitors of Type IIP supernovae (SNe). They are expected to have dense winds with mass-loss rates up to 10−4 M⊙ yr−1. We have created a database of available X-ray lightcurves of SNe. Type IIP SNe are found to have the lowest X-ray luminosities among all classes, which is surprising given the high mass-loss rate winds expected from their red supergiant progenitors, and therefore the high density medium into which Type IIP SNe are expected to expand into. We show that the low X-ray luminosity sets a limit on the mass-loss rate of the progenitor star which can collapse to become a RSG, which is about 10−5 M⊙ yr−1. This in turn can be used to set a limit on the initial mass of a RSG star which can become a Type IIP progenitor, which is about 19 M⊙. This is consistent with the limit obtained via direct optical progenitor identification. Optically identified progenitors of Type IIP SNe are found to be RSGs with masses less than about 17 M⊙ (Smartt (2009)). We discuss the implications of this result for stellar evolution, theorize on the fate of RSG stars with initial mass > 19 M⊙, and discuss what type of SNe they will produce at the end of their lifetime.

Studies of high redshift galaxies reveal compact sub-galactic regions of star formation, known as ‘clumps’. These ‘clumpy’ galaxies are useful for the study of galactic outskirts by enabling us to examine the radial progression of clumps over large time scales. We use the first deep high resolution NUV image from the Hubble Space Telescope covering intermediate redshifts to explore the implications this radial progression may have on galaxy evolution. From the analysis of 209 clumpy galaxies, we find that higher redshift clumps dominate the outer regions of galactic outskirts. This indicates that clumps may be migrating from the outskirts inward toward their galactic centers.

We carried out a systematic study of the electronic structure of doubly-ionized Fe-peak species, from Sc III to Ni III. The magnetic dipole (M1) and electric quadrupole (E2) transition probabilities were computed using the pseudo-relativistic Hartree-Fock (HFR) method and the central Thomas-Fermi-Dirac-Amaldi potential approximation implemented in the AUTOSTRUCTURE code. This multi-platform approach allowed for consistency checks and intercomparison and has proven very useful in many previous works for estimating the uncertainties affecting the radiative data.

A growing number of SNe now show evidence for significant interaction between the forward shock and a pre-existing circumstellar medium (CSM) formed by the pre-SN mass-loss. The SN community likes to argue that it can indirectly constrain the progenitor systems for these SNe by measuring the wind speeds, densities, compositions, and asymmetries of the CSM. The measurements, however, rely on a number of assumptions and can result in degeneracies that straddle the divide between RSGs and more massive stars. Furthermore, the implications of the measured properties may sometimes be simplified to fit a SN expert's relatively basic understanding of stellar wind parameters. Given the opportunity to have experts in massive stars, cool stars, and supernovae together in the same room, I thought it would be a good opportunity to review the different methods employed by the SN community to measure mass-loss rates. I will then provide an update from a recent Spitzer survey on the measured CSM properties from different subclasses of SNe with known shock interaction (including SLSNe, SNe II, IIn, Ibc, and even Ia-CSM). Finally, I will present new HST data on the SLSN Type IIn SN 2006gy and discuss the implications on the progenitor system and pre-SN mass-loss.

The red supergiant phase is an important phase of the evolution of massive star, as it mostly determines its final stages. One of the most important driver of the evolution during this phase is mass loss. However, the mass-loss rates prescription used for red supergiants in current stellar evolution models are still very inaccurate.

Varying the mass-loss rate makes the star evolve for some time in yellow/blue regions of the HRD, modifying the number of RSGs in some luminosity ranges. Figure 1 shows how the luminosity distribution of RSGs is modified for various mass-loss prescriptions. This illustrates that it is theoretically possible to determine at least roughly what is the typical mass loss regime of RSGs in a stellar evolution perspective.

We present the first experimentally determined oscillator strengths for the Pb ii transitions at 1203.6 Å and 1433.9 Å, obtained from lifetime measurements made using beam-foil techniques. We also present new detections of these lines in the interstellar medium from an analysis of archival spectra acquired by the Space Telescope Imaging Spectrograph onboard the Hubble Space Telescope. Our observations of the Pb ii λ1203 line represent the first detection of this transition in interstellar gas. Our experimental f-values for the Pb ii λ1203 and λ1433 transitions are consistent with recent theoretical results, including our own relativistic calculations, but are significantly smaller than previous values based on older calculations. Our new f-value for Pb ii λ1433 (0.321 ± 0.034) yields an increase in the interstellar abundance of Pb of 0.43 dex over estimates based on the f-value listed by Morton. With our revised f-values, and with our new detections of Pb ii λ1203 and λ1433, we find that the depletion of Pb onto interstellar grains is not nearly as severe as previously thought, and is very similar to the depletions seen for elements such as Zn and Sn, which have similar condensation temperatures.

The photochemistry of CO and its isotoplogues affects the structure and evolution of many astronomical environments, including interstellar clouds, circumstellar disks around newly formed stars, and the envelopes surrounding highly evolved stars. When in the presence of a strong ultraviolet field, the primary destruction mechanism for interstellar and circumstellar CO is photodissociation, which is entirely governed by discrete line absorption into predissociating levels in the wavelength range 91.2 to 111.8 nm. Because the CO spectrum consists primarily of resolved line features, self-shielding effects in high-column density environments can lead to strong isotopic fractionation signatures in both CO and elemental oxygen and carbon; for example, CO self-shielding in the solar nebula has been invoked to explain the unusual oxygen isotope ratios observed in the earliest solar system condensates, viz. calcium-aluminum inclusions (CAIs) in primitive meteorites.

The morphological appearance of massive stars during their evolution and at the pre-SN stage is very uncertain, both from theoretical and observational perspectives. We recently developed coupled stellar evolution and atmospheric modeling of stars done with the Geneva and CMFGEN codes, for initial masses between 9 and 120 M⊙. We are able to predict the observables such as the high-resolution spectrum and broadband photometry. Here I discuss how the spectrum of a massive star changes across its evolution and before death. Our models allow, for the first time, direct comparison between predictions from stellar evolution models and observations of SN progenitors.

We will identify new molecules in the interstellar medium by comparing a catalog of theoretical spectra generated by the NASA Ames quantum chemistry group with recent high-resolution astronomical line surveys.

We present the observed “continuum” levels of polarization as a function of time for four well-observed Type II-Plateau supernovae (SNe II-P; Fig. 1), the class of SNe decisively determined to arise from red supergiant stars (Smartt 2009). All four objects show temporally increasing degrees of polarization through the end of the photospheric phase, with some exhibiting early-time polarization that challenge existing models (e.g., Dessart and Hillier 2011) to reproduce. A fundamental ejecta asymmetry is present in this photometrically diverse sample of type II SNe, and it probably takes different forms (e.g., 56Ni blobs/fingers, large scale deformation). We acknowledge support from NSF grants AST-1009571 and AST-1210311.

Highly accurate IR line lists are ready for 13 CO2 isotopologues and 7 SO2 isotopologues. Ames-296K IR lists carry 0.01 - 0.03 cm−1 accuracy up to 13,000 cm−1 for CO2 and 5500 cm−1 for SO2, and 90–95% intensity agreement for most observable bands. Good for atmospheric modeling on Venus and Exoplanets.

It is yet well understood how mass-loss rates from evolved stars depend on metallicities. With a half of the solar metallicity and the distance of only 50 kpc, the evolved stars of the Large Magellanic Cloud (LMC) are an ideal target for studying mass loss at low metallicity. We have obtained spectra of red-supergiants in the LMC, using the Hershel Space Observatory, detecting CO thermal lines fro J=6–5 up to 15–14 lines. Modelling CO lines with non-LTE Radiative transfer code suggests that CO lines intensities can be well explained with high gas-to-dust ratio, with no obvious reduction in mass-loss rate at the LMC. We conclude that the luminosities of the stars are primary factors on mass-loss rates, rather than the metallicity.