Abstract

Contributed Talk - Splinter StarFormation   (MW-1250)

DREAM: Dust pRoperties Explored Across galactic Metallicity boundaries

Wonju Kim, Friedrich Wyrowski, Amélie Saintonge, Alvaro Sanchez-Monge, Axel Weiß, Gary Fuller, Dario Colombo
MPIfR, Institute of Space Sciences (ICE, CSIC), University of Manchester, University of Bonn

Dust grains play a crucial role in the interstellar medium (ISM), acting as coolants and enabling the formation of molecular hydrogen (H2), which drives star formation. In addition, other molecular species form on grains, and grains can also store different molecules on their surfaces. As products of star formation, dust grains are continually reshaped and redistributed within the molecular clouds where stars form. However, the links between dust-grain properties and interstellar molecules still remain poorly constrained. To address this, we initiate a pilot investigation for the DREAM program (Dust pRoperties Explored Across galactic Metallicity boundaries) to understand the relationship between dust properties and molecular gas in star-forming molecular clouds across the inner and outer Galactic disks. For this, we used IRAM 30m NIKA2 1mm and 2 mm dust continuum data (and the upcoming APEX AMKID 850 μm data) together with molecular line mapping observations from the APEX 12m, IRAM 30m, and Yebes 40m telescopes. Our analysis of an inner Galactic cloud reveals that the dust emissivity spectral index (β), derived from NIKA2 data, varies significantly with SiO abundance: β becomes steeper (> 1.5) in regions with high SiO abundances (> 5–6 × 10^-9). In contrast, regions with low β values (flatter slopes) show no significant SiO emission or very low SiO abundances, X(SiO) <= a few of 10^-10. These results suggest that molecular species associated with dust-grain evolution processing are highly sensitive to dust-grain properties and their variations within the same environment. I will present these initial results on the dust emissivity spectral index and discuss their implications for shock tracers and dust–gas coupling in star-forming regions. I will also present newly obtained NIKA2 continuum data for the outer Galactic molecular clouds, along with a comparison of molecular gas and the dust emissivity spectral index in lower-metallicity environments. Preliminary analysis of the β values for these outer Galactic molecular clouds indicates generally lower values, which may suggest different dust properties in low-metallicity environments. The DREAM program aims to provide insights into dust properties across the Milky Way and facilitate comparisons with external galaxies.