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Title: DUST AROUND R CORONAE BOREALIS STARS. II. INFRARED EMISSION FEATURES IN AN H-POOR ENVIRONMENT

Residual Spitzer/Infrared Spectrograph spectra for a sample of 31 R Coronae Borealis (RCB) stars are presented and discussed in terms of narrow emission features superimposed on the quasi-blackbody continuous infrared emission. A broad {approx}6-10 {mu}m dust emission complex is seen in the RCBs showing an extreme H-deficiency. A secondary and much weaker {approx}11.5-15 {mu}m broad emission feature is detected in a few RCBs with the strongest {approx}6-10 {mu}m dust complex. The Spitzer infrared spectra reveal for the first time the structure within the {approx}6-10 {mu}m dust complex, showing the presence of strong C-C stretching modes at {approx}6.3 and 8.1 {mu}m as well as of other dust features at {approx}5.9, 6.9, and 7.3 {mu}m, which are attributable to amorphous carbonaceous solids with little or no hydrogen. The few RCBs with only moderate H-deficiencies display the classical ''unidentified infrared bands (UIRs)'' and mid-infrared features from fullerene-related molecules. In general, the characteristics of the RCB infrared emission features are not correlated with the stellar and circumstellar properties, suggesting that the RCB dust features may not be dependent on the present physical conditions around RCB stars. The only exception seems to be the central wavelength of the 6.3 {mu}m feature, which is blueshifted inmore » those RCBs showing also the UIRs, i.e., the RCBs with the smallest H deficiency.« less
Authors:
 [1] ;  [2] ;  [3]
  1. Instituto de Astrofisica de Canarias, C/Via Lactea s/n, E-38200 La Laguna (Spain)
  2. 543, 17th Main, IV Sector, HSR Layout, Bangalore 560102 and Indian Institute of Astrophysics, Bangalore 560034 (India)
  3. W. J. McDonald Observatory, University of Texas at Austin, 1 University Station, C1400, Austin, TX 78712-0259 (United States)
Publication Date:
OSTI Identifier:
22131009
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 773; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COSMIC DUST; EMISSION; FULLERENES; HYDROGEN; INFRARED SPECTRA; SPITZER THEORY; STELLAR CORONAE