Circumstellar Structure around Evolved Stars in the Cygnus-X Star Formation Region

Abstract

We present observations of newly discovered 24 micron circumstellar structures detected with the Multiband Imaging Photometer for Spitzer (MIPS) around three evolved stars in the Cygnus-X star forming region. One of the objects, BD+43 3710, has a bipolar nebula, possibly due to an outflow or a torus of material. A second, HBHA 4202-22, a Wolf-Rayet candidate, shows a circular shell of 24 micron emission suggestive of either a limb-brightened shell or disk seen face-on. No diffuse emission was detected around either of these two objects in the Spitzer 3.6-8 micron Infrared Array Camera (IRAC) bands. The third object is the luminous blue variable candidate G79.29+0.46. We resolved the previously known inner ring in all four IRAC bands. The 24 micron emission from the inner ring extends ~1.2 arcmin beyond the shorter wavelength emission, well beyond what can be attributed to the difference in resolutions between MIPS and IRAC. Additionally, we have discovered an outer ring of 24 micron emission, possibly due to an earlier episode of mass loss. For the two shell stars, we present the results of radiative transfer models, constraining the stellar and dust shell parameters. The shells are composed of amorphous carbon grains, plus polycyclic aromatic hydrocarbons in the case of G79.29+0.46. Both G79.29+0.46 and HBHA 4202-22 lie behind the main Cygnus-X cloud. Although G79.29+0.46 may simply be on the far side of the cloud, HBHA 4202-22 is unrelated to the Cygnus-X star formation region.

Accepted by AJ

References in corpus (9)

• Spitzer Observations of NGC 1333: A Study of Structure and Evolution in a Nearby Embedded Cluster
• A Spitzer mid-infrared spectral survey of mass-losing carbon stars in the Large Magellanic Cloud
• Unusual Dust Emission from Planetary Nebulae in the Magellanic Clouds
• A Catalog of MIPSGAL Disk and Ring Sources
• Photometry using the Infrared Array Camera on the Spitzer Space Telescope
• Discovery of a new Wolf-Rayet star and its ring nebula in Cygnus
• Discovery of warm and dense molecular gas surrounding the ring nebula G79.29+0.46
• Multiple shells around G79.29+0.46 revealed from near-IR to millimeter data
• Tentative Discovery of a New Supernova Remnant in Cepheus: Unveiling an Elusive Shell in the Spitzer Galactic First Look Survey

Cited by in corpus (13)

• Discovery of a parsec-scale bipolar nebula around MWC 349A
• The Balloon-Borne Large Aperture Submillimeter Telescope (BLAST) 2005: A 10 deg^2 Survey of Star Formation in Cygnus X
• Gamma-ray Observation of the Cygnus Region in the 100 TeV Energy Region
• Palomar/TripleSpec observations of {\it Spitzer}/MIPSGAL~24\mic\ circumstellar shells: unveiling the nature of their central sources
• A global view on star formation: The GLOSTAR Galactic plane survey III. 6.7 GHz methanol maser survey in Cygnus X
• A systematic study of Galactic infrared bubbles along the Galactic plane with AKARI and Herschel
• The candidate luminous blue variable G79.29+0.46: a comprehensive study of its ejecta through a multiwavelength analysis
• Ammonia observations in the LBV nebula G79.29+0.46. Discovery of a cold ring and some warm spots
• The Trace of the CNO Cycle in the Ring Nebula NGC6888
• New ATCA, ALMA and VISIR observations of the candidate LBV SK-67266 (S61): the nebular mass from modelling 3D density distributions
• Observational constraints on the nature of very short gamma-ray bursts
• Gaia colour-magnitude diagrams of young open clusters: Identification in the UBC catalogue and a comparison of manual and automated analysis
• Millimetre continuum from LBV stars and their environs. NIKA2 observations and Virtual Observatory data