Lynds 1622: a nearby star forming cloud projected on Orion B?

TL;DR

This study characterizes the Lynds 1622 cloud and its pre-main sequence stars, determining their physical properties and suggesting the cloud is as distant as Orion B, with implications for star formation in the region.

Contribution

It provides detailed spectroscopic, photometric, and molecular data for Lynds 1622, establishing its distance, mass, and star formation efficiency, and clarifying its relation to Orion B.

Findings

Lynds 1622 is as distant as Orion B at about 400 pc.

The cloud's mass is approximately 1100 solar masses.

Star formation efficiency in L1622 is about 1.8%.

Abstract

We present results of optical spectroscopic and photometric observation of the pre-main sequence stars associated with the cometary shaped dark cloud Lynds 1622, and 12CO and 13CO observations of the cloud. We determined the effective temperatures and luminosities of 14 pre-main sequence stars associated with the cloud from their positions in the Hertzsprung--Russell diagram, as well as constructed their spectral energy distributions using optical, 2MASS and Spitzer IRAC and MIPS data. We derived physical parameters of L1622 from the molecular observations. Our results are not compatible with the assumption that L1622 lies on the near side of the Orion-Eridanus loop, but suggest that L1622 is as distant as Orion B. At a distance of 400 pc the mass of the cloud, derived from our CO data, is 1100 solar masses, its star formation efficiency is 1.8%, and the average age of its low-mass pre-main sequence star population is about 1 million years.