Spitzer IRAC imaging photometric study of the massive star forming region AFGL 437

TL;DR

This study uses Spitzer IRAC mid-infrared photometry to identify new young stellar objects, analyze molecular outflows, and model the properties of YSOs in the massive star-forming region AFGL 437, revealing insights into their formation and environment.

Contribution

The paper provides new IRAC-based identification of embedded YSOs, investigates molecular outflows with ratio images, and models YSO properties, offering detailed insights into the star formation processes in AFGL 437.

Findings

Identification of several new embedded YSOs near the cluster.

Detection of shocked molecular hydrogen emission in outflow lobes.

Derived masses, ages, and luminosities of YSOs using radiative transfer modeling.

Abstract

We present {\it Spitzer} IRAC mid-infrared photometry on the massive star forming region AFGL 437 (IRAS 03035+5819). From the IRAC colour-colour diagram, we identify several new embedded YSOs within 64 arcsec of the central compact cluster. Using the IRAC ratio images, we investigate the molecular outflows associated with the highly embedded young stellar object WK34 in the central cluster. We attribute the lobes seen (extended to $\sim$ 0.16 pc in the north) in the ratio map to shocked molecular hydrogen emission. IRAC images reveal a large diffuse nebulosity associated with the central cluster and extending up to $\sim$ 8.0 pc from south-west to north-east direction with its brightness gradually increasing from 3.6 to 8.0 $\mu$m. A dense box-car-shaped nebula (more than 2.0 pc in size) situated to the south-west of the cluster shows molecular hydrogen emission that may have been caused by shock waves from the compact cluster sources. It seems that these sources are also responsible for the infrared-bright nebulosity. Using a 2D radiative transfer model, we derive from the spectral energy distributions, the mass, age and luminosity of all the YSOs identified within the central cluster. The SED modelling shows that the driving engine of the outflows, WK34, appears to be massive but very young and deeply embedded. The weighted mean values of the masses and ages of the 21 YSOs derived from the model are in the range 1-10 \msun and 10$^{4.1 - 6.4}$ yr respectively; while their luminosities are in the range of 10$^{0.47-3.48}$ L$_{\odot}$.