Young Stellar Object Candidates in IC 417

Abstract

IC 417 is in the Galactic plane, and likely part of the Aur OB2 association; it is ∼2 kpc away. Stock 8 is one of the densest cluster constituents; off of it to the east, there is a “nebulous stream” (NS) that is dramatic in the infrared (IR). We have assembled a list of literature-identified young stellar objects (YSOs), new candidate YSOs from the NS, and new candidate YSOs from IR excesses. We vetted this list via inspection of the images, spectral energy distributions (SEDs), and color–color/color–magnitude diagrams. We placed the 710 surviving YSOs and candidate YSOs in ranked bins, nearly two-thirds of which have more than 20 points defining their SEDs. The lowest-ranked bins include stars that are confused, or likely carbon stars. There are 503 in the higher-ranked bins; half are SED Class III, and ∼40% are SED Class II. Our results agree with the literature in that we find that the NS and Stock 8 are at about the same distance from Earth (as are the rest of the YSOs), and that the NS is the youngest region, with Stock 8 being a little older. We do not find any evidence for an age spread within the NS, consistent with the idea that the star formation trigger came from the north. We do not find that the other literature-identified clusters here are as young as either the NS or Stock 8; at best, they are older than Stock 8, and they may not all be legitimate clusters.

Keywords

• Star formation
• Star forming regions