All Tables

Table 1: The detection rates of the PAH 3.3 $\mu$ m feature in the ISO and ISAAC samples. T stands for the total of classified sample sources, I and II refer to the Meeus groups and E represents the embedded sources. The last row gives the detection rates in the combined ISO+ISAAC sample. When two percentages are given, the second refers to the detection rate including tentative detections. The detection rate in group I is significantly higher than in group II (confidence level >99.5%).
Table 2: Some disk parameters of the (candidate) nanodiamond sources. The Meeus group indicates the overall geometry of the disk. The ratio of the total IR excess to the stellar luminosity, $L_{\rm exc}/L_\star$ , indicates the fraction of stellar flux that is captured and reprocessed by the disk. For passive disks, this number represents the fraction of the sky covered by the disk, as seen from the central star. The ratio for T CrA is likely overestimated due to strong nearby IR emission, not directly linked to the system. The parameter n is the spectral index in the 450 $\mu$ m-1.3 mm range, defined by $\lambda F_\lambda \propto \lambda ^{-n}$ .
Table 3: Some stellar parameters of the (candidate) nanodiamond targets, and the observed nanodiamond 3.53 $\mu$ m luminosity L_3.5. The median value of each stelllar parameter in the total sample is given as a reference. Values taken from Hamaguchi et al. (2005); Mora et al. (2001); Shore et al. (1990); Houk & Cowley (1975); Acke et al. (2004); Fuente et al. (2001); van den Ancker et al. (1998); Habart et al. (2003); Finkenzeller & Mundt (1984), AV04 and references therein.
Table 5: The detected features in the 3 micron region of the sample stars. The sample stars have been classified in Meeus groups I and II (Meeus et al. 2001). Targets with A_V exceeding 4 are classified as embedded sources (E). Sources with unknown or uncertain classification are flagged with "?''. The measured line fluxes and peak-over-continuum ratios of four spectral features are given: the Pfund ${\delta }$ emission line at 3.296 $\mu$ m, the PAH 3.3 $\mu$ m feature and the nanodiamond features at 3.43 and 3.53 $\mu$ m. Tentative detections (line flux between 1-3 $\sigma$ ) are indicated with a. The flag b indicates detected features of unclear origin, either linked to data reduction artefacts, nanodiamonds or an unknown carrier.
Table 4: The observation log of the sample stars The right ascension (RA), declination (Dec) and date of the ISAAC observations are indicated. The date, UT and integration time T of the observation are given. We have assigned a quality label (Q) to the ISAAC spectra: G-good quality; L-low flux levels (<0.5 Jy); J-large flux-level jump (>50%) between the 3.3 and 3.5 micron spectrum. The seeing at $\lambda$ = 0.5 $\mu$ m, estimated by the VLT Astronomical Site Monitor (ASM), is given at the time of the 3.3 and 3.5 $\mu$ m ISAAC observations respectively. The final column lists the spectral calibrator stars. These standard stars have been observed during the same night as the science target, unless when flagged with $\star$ .