Young stellar and substellar objects in IC 348 and Barnard 5 in the Perseus molecular cloud complex

Bhavana Lalchand^1*

¹Graduate Institute of Astronomy, National Central University, Zhongli district, Taoyuan City, Taiwan

* Presenter:Bhavana Lalchand, email:bhavana_lalchand@gm.astro.ncu.edu.tw

Brown dwarfs have masses between stars, which form by gravitational contraction out of molecular clouds,
and exoplanets, which condense in young circumstellar disks. With no sustainable core fusion, brown dwarfs
continue to fade quickly in brightness and temperature, thereby best-studied soon after birth, that is,
in star-forming regions. A comprehensive census of young stars and brown dwarfs is the critical
first step to diagnose the origin of stellar and substellar masses --- the initial mass function.
Such a member list identified by conventional infrared colors is often hampered by an excessive
contamination rate, mainly due to highly reddened background stars. We have developed a technique
of imaging photometry with a custom-made filter to quantify the level of water absorption, typically seen in
the spectra of M-L-T-Y type objects, near 1.45 microns, supplemented with deep J and H photometry to account for
interstellar reddening. Follow-up infrared spectroscopy vindicates a confirmation rate > 80%, reducing
the number of candidates from hundreds to dozens. Here we report the discovery of substellar members
in IC 348 and in Barnard 5 (LDN-1471), both located at the eastern edge of the Perseus cloud complex.
At a distance of 300 pc, the IC348 cluster comprises nearly 500 members, including a luminous B5 star.
Compared to the main cluster (3~Myr), a region some 10 arcmin to the southwest contains embedded objects
and outflows, signifying ongoing star formation (1~Myr). Somewhat detached from the complex, and likely
closer (~250 pc), the Barnard 5 globule is also known to host a group of protostars and Herbig-Haro
objects, yet its low-mass membership is much unexploited. We also combined data from Gaia eDR3, WISE, 2MASS,
and PanSTARRS to characterize candidate stellar members in Barnard 5.

Keywords: Star-forming, Young-stellar objects, Brown dwarfs, young clusters