2023/10/07 by Massimo Robberto, Robberto, Massimo, Mario Gennaro +15
Chemistry · Earth and Planetary Sciences · Physics and Astronomy · #Astrophysics and Star Formation Studies #Astrophysics of Galaxies (astro-ph.GA) #Atmospheric Ozone and Climate #FOS: Physical sciences #Solar and Stellar Astrophysics (astro-ph.SR) #Spectroscopy and Laser Applications
paper · pdf · doi:10.48550/arxiv.2310.04888
openalex publication_date 2023/10/07 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We performed a HST/WFC3-IR imaging survey of the young stellar cluster NGC 2024 in three filters probing the 1.4~μm H2O absorption feature, characteristic of the population of low mass and sub-stellar mass objects down to a few Jupyter masses. We detect 812 point sources, 550 of them in all 3 filters with signal to noise greater than 5. Using a distance-independent two-color diagram we determine extinction values as high as AV≃ 40. We also find that the change of effective wavelengths in our filters results in higher AV values as the reddening increases. Reconstructing a dereddened color-magnitude diagram we derive a luminosity histogram for both the full sample of candidate cluster members and for an extinction-limited sub-sample containing the 50% of sources with AV\lesssim 15. Assuming a standard extinction law like Cardelli et al. (1989) with a nominal RV=3.1 we produce a luminosity function in good agreement with the one resulting from a Salpeter-like Initial Mass Function for a 1~Myr isochrone. There is some evidence of an excess of luminous stars in the most embedded region. We posit that the correlation may be due to those sources being younger, and therefore overluminous than the more evolved and less extinct cluster's stars. We compare our classification scheme based on the depth of the 1.4μm photometric feature with the results from the spectroscopic survey of Levine et al. (2006), and we report a few peculiar sources and morphological features typical of the rich phenomenology commonly encountered in young star-forming regions.