Year: 2019
Type: article
Abstract: Interstellar graphene could be present in the interstellar medium (ISM), resulting from the photochemical processing of polycyclic aromatic hydrocarbon (PAH) molecules and/or collisional fragmentation of graphitic particles. Indeed, by comparing the observed ultraviolet (UV) extinction and infrared (IR) emission of the diffuse ISM with that predicted for graphene, as much as ∼2% of total interstellar carbon could be locked up in graphene without violating the observational constraints. While the possible detection of planar C 24 , a small piece of a graphene sheet, has been reported towards several Galactic and extragalactic planetary nebulae , graphene has not yet been detected in interstellar environments. In this work, we search for the characteristic IR features of C 24 at ∼6.6, 9.8 and 20 μm toward Sgr B2, a high-mass star formation region, and find a candidate target toward R.A. (J2000) = 267.05855° and Decl. (J2000) = −28.01479° in Sgr B2 whose Spitzer /IRS spectra exhibit three bands peaking at ∼6.637, 9.853 and 20.050 μm which appear to be coincident with those of C 24 . Possible features of C 60 are also seen in this region. The candidate region is a warm dust environment heated by massive stars or star clusters, associated with a WISE spot (a tracer of star formation activity), close to the HII region candidate IRAS 17450–2759, and is surrounded by seven young stellar object candidates within ∼5′, suggesting that the creation and/or excitation of C 24 could be related to star formation activities.
Institutions: Xiangtan University, University of Missouri
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2943716067