All Tables

Table 1: Sample of candidate massive YSOs. Column 1: IRAS point source catalogue number; Col. 2: Name corresponding H II region; Col. 3: Number K-band point source (Kaper et al. 2006); Cols. 4, 5: right ascension and declination; Cols. 6, 7: K and J-K(from Kaper et al. 2006); Col. 8: $A_{\rm V}$ applied to deredden the sources (see text); Cols. 9, 10: Resulting absolute K-band magnitude and intrinsic $(J-K)_{\rm0}$ ; Col. 11: Adopted distance with in between brackets the reference: B96: Bronfman et al. (1996) with the galactic rotation model of Brand & Blitz (1993), C87: Caswell & Haynes (1987) C91: Chini & Neckel (1981), C95: Carpenter et al. (1995), F02: Figuerêdo et al. (2002), K89: Koempe et al. (1989), K94: Kurtz et al. (1994), K01: Karnik et al. (2001), Kpc: Kurtz, private communication, L92: Liseau et al. (1992), S90: Simpson & Rubin (1990), T91: Tapia (1991), W89: Wood & Churchwell (1989b), W97: Walsh et al. (1997).
Table 2: Identification of the lines detected in the K-band spectra of candidate massive YSOs. Column 1 lists the rest wavelength, Col. 2 the corresponding element and Col. 3 the line transition.
Table 3: Equivalent width (EW) measurements of the emission line objects. Upper table: Cols. 2-7 give the EW for the spectral lines in the Br $\gamma$ setting. The EWs are measured in Å ngström and emission is given as positive. In Col. 8 the FWHM of Br $\gamma$ is given in km s^-1. Columns 9 and 10 show whether the CO and Pfund-lines are present in the spectra or not. ("-'' means not present, "n'' means not observed). Middle table: the EW measurements of the Pf-lines. The "b'' means that the line could not be measured because of blending with the CO lines. The Pf-lines of 16571nr1281 are double peaked with an average peak separation of $189 \pm 33$ km s^-1. Lower table: the EW measurements of the CO first-overtone bandheads. The "b'' means that the lines are blended with cold CO absorption lines or Pfund lines.
Table 4: The FWHM of the Br $\gamma$ line compared with that of the hydrogen Pf25 line. The Pf23 line is stronger than the Pf25, but this line is heavily contaminated by residuals of atmospheric lines. For the fitting of 18006nr766 the Pf23 line is used, because Pf25 is not detected. In the last column the flux-ratio of Br $\gamma$ and Pf25 is listed.
Table 5: Summary of the spectral and photometric properties of the well studied objects as discussed in Sect. 4. Column 1: object name; Col. 2: spectral type; Cols. 3-6: spectral features detected in their K-band spectra; Cols. 7 (J - K) value, dereddened for foreground extinction; Col. 8: absolute, dereddened K-band magnitude; Col. 9: references: G87: Geballe & Persson (1987), C89: Carr (1989), C93: Chandler et al. (1993), C95: Chandler et al. (1995), vdA00: van den Ancker et al. (2000), S83: Scoville et al. (1983), L04: Lenorzer et al. (2004), vdA04: E02: Eiroa et al. (2002), van der Ancker (2004), C00: Clark & Steele (2000), D94: Dougherty et al. (1994), M88: McGregor et al. (1988), M96: Morris et al. (1996), V99: Voors (1999). $\dagger$ : These values are for the B[e] supergaints.
Table 6: Summary of the properties of the massive YSOs. Columns 2-4: spectral lines (-: not present, +: present, n: not observed); Col. 5: is the source the counterpart of a radio UCHII?; Col. 6: spectral evidence for a circumstellar disk. (+: evidence for a disk); Col. 7: spectral type estimated based on the position in the CMD (Fig. 1); Col. 8: spectral type based on the IRAS luminosity of the IRAS source. This is an upper limit on the spectral type of the massive YSO, as usually more stars contribute to the IRAS flux. Column 9: spectral type estimate based on other methods. Column 10: properties of the surrounding cluster, taken from Kaper et al. (2006). The OB star spectra are discussed in Bik et al. (2005). References: K94: Kurtz et al. (1994, radio flux UCHII region); P03: Persi & Tapia (2003, mid-infrared luminosity); Kpc: Kurtz, private communication (radio flux UCHII region); N84: Neckel & Staude (1984, optical spectroscopy); C00: Clark & Steele (2000, Br)tex2html_wrap_inline3659# absorption, similarity with Be stars#; C87: Caswell & Haynes (1987, single dish radio observations and assuming that a single star is responsible for the ionisation); G02: Gómez et al. (2002); B03: Barbosa et al. (2003); K01: Karnik et al. (2001).
Table 7: Two different effects are responsible for the destruction of circumstellar disks around O stars; the photo-evaporation process and the direct interaction between the wind and the disk. In the first 3 columns, the stellar parameters are given used in the calculation of the timescales (Mokiem et al. 2004; Lenorzer et al. 2004). In Col. 4, the gravitational radius is given. Beyond this radius matter is removed by photoevaporation, while inside of it, the stellar wind directly removes material from the disk. Cols. 5 and 6 give the typical timescales for these two processes. The formulae are taken from Hollenbach et al. (2000,1994).