The new star forming site NGC 6334 IV (MM3)^*

¹ INAF-IASF, Sez. di Roma, via Fosso del Cavaliere 100, 00133 Roma, Italia e-mail: paolo.persi@iasf-roma.inaf.it
² Instituto de Astronomía, UNAM, Apartado Postal 877, Ensenada, Baja California, CP 22830, Mexico e-mail: mt@astrosen.unam.mx
³ Las Campanas Observatory, Carnegie Institution of Washington, Casilla 601, La Serena, Chile e-mail: miguel@lco.cl
⁴ Observatorio Astronómico de Córdoba, Laprida 854, 5000 Córdoba, Argentina e-mail: mercedes@oac.uncor.edu

Received: 1 September 2008
Accepted: 27 October 2008

Abstract

Aims. The eastern part of the massive star forming region NGC 6334 IV is characterized by the presence of the millimeter continuum sources MM3, MM4, and the optically thin HII region G351.24+0.65. Here we study the star formation in this part of the cloud.

Methods. We imaged this region, here named NGC 6334 IV (MM3), at sub-arcsec resolution in , H₂, Br γ, and in the mid-infrared, from 8.9 to 12.7. In addition, we used IRAC/Spitzer and ISOCAM images.

Results. From the analysis of the IRAC color-color and versus K_s – [3.6] diagrams, we found 18 embedded very young stellar objects within an area of 75. One of these sources, IR-MM3 (IRS 8E), shows a very steep energy distribution with an infrared spectral index of and . This protostar, which coincides with an OH maser source and with the continuum millimeter source MM3, is the exciting source of two hydrogen molecular knots found in our H₂ image. Two sources (IRS 18, and 19) with infrared excess and a steep SED are probably associated with the HII region G351.24+0.65. The IRAC and ISOCAM images indicate the presence of extended PAH emission in the region.

Conclusions. We have discovered a new center of massive star formation in the giant molecular cloud complex NGC 6334.