SIMBAD references

2012AJ....143....3D - Astron. J., 143, 3 (2012/January-0)

The young cluster in IC 1274.


Abstract (from CDS):

IC 1274 is a faintly luminous nebula lying on the near surface of the Lynds 227 (L227) molecular cloud. Its cavity-like morphology is reminiscent of a blistered star-forming region. Four luminous, early-type (B0-B5) stars are located within a spherical volume ∼5' in diameter that appears to be clear of heavy obscuration. Approximately centered in the cleared region is the B0 V star HD 166033, which is thought to be largely responsible for the cavity's excavation. Over 80 Hα emission sources brighter than V ∼ 21 have been identified in the region. More than half of these are concentrated in IC 1274 and are presumably members of a faint T Tauri star population. Chandra Advanced CCD Imaging Spectrometer imaging of a nearby suspected pulsar and time-variable γ-ray source (GeV J1809-2327) detected 21 X-ray sources in the cluster vicinity, some of which are coincident with the early-type stars and Hα emitters in IC 1274. Deep (V ∼ 22) optical BVRI photometry has been obtained for the cluster region. A distance of 1.82±0.3 kpc and a mean extinction of AV∼ 1.21±0.2 mag follow from photometry of the early-type stars. Using pre-main-sequence evolutionary models, we derive a median age for the Hα emitters and X-ray sources of ∼1 Myr; however, a significant dispersion is present. Our interpretation of the structure of IC 1274 and the spatial distribution of Hα emitters is that the early-type stars formed recently and are in the process of ionizing and dispersing the molecular gas on the near surface of L227. The displaced material was driven against what remains of the molecular cloud to the east, enabling the formation of the substantial number of T Tauri stars found there. A dispersed population of Hα emitters is also found along the periphery of L227, IC 1275, and IC 4684. These sources, if pre-main-sequence stars, appear to have formed in relative isolation compared to the dense cluster environment of IC 1274 or, alternatively, may be older and have drifted further from their formation sites. We identify a V ∼ 21.5 star very near the position of X-ray source 5, the assumed γ-ray source and young pulsar candidate. However, the lack of distinctive characteristics for this source, coupled with the density of faint stars in this region, suggest that this may be a random superposition.

Abstract Copyright:

Journal keyword(s): ISM: individual (IC 1274, Lynds 227) - stars: pre-main sequence - stars: variables: T Tauri, Herbig Ae/Be

VizieR on-line data: <Available at CDS (J/AJ/143/3): table3.dat table5.dat>

Nomenclature: Table 3: IfAHA NNN (Nos 686-762) added.

Simbad objects: 121

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