Research | Gsuarez

RESEARCH INTERESTS

My principal research interests are the detection and characterization of substellar object atmospheres to contribute to our understanding of the chemical composition and physical properties and effects in brown dwarf and planetary atmospheres. I am particularly interested in the formation, composition, and evolution of dust clouds in these atmospheres. Furthermore, I am interested in studies of the (sub)stellar initial mass function in young stellar associations and the solar neighborhood to investigate its origin and the universality of the star/brown dwarf forming process.

MY RESEARCH

Brown Dwarfs and Giant Exoplanets

Dust Clouds in Substellar Atmospheres

We reprocessed and analyzed all 113 mid-infrared spectra of field M5–T9 dwarfs observed with the Spitzer IRS and found results that shed light on the formation, evolution, composition, and distribution of dust clouds in substellar atmospheres. By analyzing the ~9 micron silicate absorption – the only direct evidence of silicate clouds – we found the following results, which constitute a paper series (Suárez et al. 2021, Suárez & Metchev 2022, Suárez & Metchev 2023, Suárez et al. 2023):

Silicate clouds are near ubiquitous in L-type atmospheres.
Silicate clouds form, then thicken, and sediment in the 2000–1300 K temperature range.
Low-gravity atmospheres are cloudier due to a slower settling of dust clouds.
Young atmospheres may have iron-rich silicate clouds.
Variable objects are more likely to have higher dust cloud opacity.
Equatorial latitudes are cloudier compared to the poles.

These results show the relevance of clouds and viewing geometry in explaining the appearance of brown dwarf and planetary atmospheres.

Figure 1: Illustration of the formation and evolution of dust clouds in planetary and brown dwarf atmospheres from a NASA press release on our study in Suárez & Metchev (2022).

Figure 2: Objects viewed equator-on exhibit higher cloud opacity and, therefore, are redder than objects viewed near pole-on (Suárez et al. 2023).

Download 113 mid-infrared spectra of all M5-T9 field dwarfs observed with Spitzer/IRS

Performance of Atmospheric Models for Ultracool Dwarfs

We assembled in Suárez et al. (2021a) the most comprehensive (0.8–26 μm; see Figure) spectral energy distribution (SED) of an intermediate-gravity L/T transition dwarf. We found that models with condensates clouds and non-equilibrium chemistry better reproduce the full SED and that young (≈0.1–0.3 Gyr) early-T dwarfs on average have ≈140 K lower effective temperatures, ≈20% larger radii, and similar bolometric luminosities compared to old (>1 Gyr) field dwarfs with similar spectral types.

Star Formation

Initial Mass Function (IMF)

As the main product of my PhD thesis project (Suárez, 2019), we present in Suárez et al. (2019) the mass distribution (IMF) of a young stellar association from planetary-mass objects to intermediate/high-mass stars (see Figure). This study represents, to our knowledge, the most complete IMF to date in terms of both mass coverage (0.012–13 Msun) and spatial distribution (up to a 1.1 deg-radius area), and allowed us to investigate the environmental dependence of the IMF.

Core Mass Function (CMF)

To test the idea of a direct connection between the IMF and the CMF, we used in Suárez et al. (2021b) high-resolution ALMA observations to construct the CMF of the massive star-forming clump G33.92+0.11, which turned out to be in agreement with a number of CMFs in diverse star-forming regions. We use Monte Carlo simulations to compare the resulting CMF to the Salpeter IMF and found that they are statistically indistinguishable (see Figure). This result is consistent with the idea that the form of the IMF is inherited from the CMF.