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J/A+A/527/A62    HK photometry in an UCHII region near Sh2-217  (Brand+, 2011)

Triggered star formation at the borders of the HII region Sh 2-217. Brand J., Massi F., Zavagno A., Deharveng L., Lefloch B. <Astron. Astrophys. 527, A62 (2011)> =2011A&A...527A..62B
ADC_Keywords: H II regions; Stars, normal; Photometry, CCD; Photometry, infrared Keywords: stars: formation - ISM: clouds - ISM: individual objects: Sh 2-217 Abstract: We study stars and gas in and around the HII region Sh 2-217 to see if the various physical parameters derived from the data (such as column densities, masses, sizes, and timescales) are consistent with the predictions of a simple model of the collect-and-collapse mechanism. This should indicate whether stars forming in molecular gas at the borders of the HII region could have been triggered by the expansion of the ionized gas. We observed the emission of various molecules and transitions towards Sh 2-217, and obtained both near-infrared photometry in the H and K bands, and near-infrared images in [FeII] and H2 narrow-band filters of the stars in a molecular condensation at the edge of the HII region, where an UC HII region is also located. Description: Coordinates and photometric parameters (magnitudes and colours) are presented of the stars located in a molecular condensation on the SW-border of the Galactic HII region Sh2-217. The data were obtained on January 4, 2004 with the 3.58-m Telescopio Nazionale Galileo (TNG; La Palma, Canary Islands, Spain). Near-infrared observations were carried out through H and K' broad-band filters with the camera NICS. The image scale is 0.25arcsec/pixel, yielding a field of view of about 4.2'x4.2'. Observing strategy and exposure times are described in Deharveng et al. (2006A&A...458..191D), the only difference being that the dithering sequence for the H-band images was the same as adopted for K'. The data reduction steps adopted are outlined in Deharveng et al. (2006A&A...458..191D). Aperture photometry was done using the DAOPHOT package in IRAF. We followed the same procedure described in Deharveng et al. (2006A&A...458..191D) to obtain aperture photometry, after which PSF-fitting photometry was performed. Although the seeing was good (<1"), the night was barely photometric, so we calibrated our H, K' photometry with that performed on the same field by Deharveng et al. (2003, Cat. J/A+A/399/1135). We calculated the difference in magnitudes for each coinciding source and plotted it against our derived instrumental H-K'. A colour term was present in K' because of the difference between the K and K' filters. After a best-fit calibration, a residual r.m.s. of about 0.2mag. was present in the difference between our photometry and that of Deharveng et al. (2003, J/A+A/399/1135), probably because of the different seeing and possibly also due to the intrinsic variability of young stars. Our photometry is thus on the same HK standard system as Deharveng et al. (2003, J/A+A/399/1135). Sources with K, H < 11-12 are in the non-linear regime or saturated, but such bright objects are few in number and lie outside the cluster, and are probably foreground stars. The approximate limiting magnitudes are K=18.48 and H=19.52, much deeper than achieved by Deharveng et al. (2003, J/A+A/399/1135). We estimate completeness limits of approximately K=16.5 and H=17.5 from the peak in histograms of the number of detected sources as a function of magnitude, after binning in 1mag. intervals. The astrometric calibration of the frames was obtained by measuring the position on the image of a sample of stars and fitting those positions to the equatorial coordinates given by Deharveng et al. (2006A&A...458..191D), using tasks of STSDAS/IRAF. The typical accuracy of this procedure is of the order of 1". File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table7.dat 66 812 Coordinates, magnitudes, and colours for 812 stars in an UCHII region near Sh 2-217
See also: J/A+A/399/1135 : JHK photometry around Sh 217 and Sh 219 (Deharveng+, 2003) Byte-by-byte Description of file: table7.dat
Bytes Format Units Label Explanations
1- 2 I2 h RAh Right Ascension J2000 (hours) 4- 5 I2 min RAm Right Ascension J2000 (minutes) 7- 11 F5.2 s RAs Right Ascension J2000 (seconds) 13 A1 --- DE- Declination sign (J2000) 14- 15 I2 deg DEd Declination J2000 (degrees) 17- 18 I2 arcmin DEm Declination J2000 (minutes) 20- 24 F5.2 arcsec DEs Declination J2000 (seconds) 26 A1 -- l_Kmag [>] indicates lower limit K-band magnitude (records 669 to 812 only) (1) 27- 32 F6.3 mag Kmag TNG/NICS K'-band (2.2um) magnitude 34- 38 F5.3 mag e_Kmag ? Uncertainty in K-band magnitude (2) 40 A1 -- l_Hmag [>] indicates lower limit H-band magnitude (records 647 to 668 only) (3) 41- 46 F6.3 mag Hmag TNG/NICS H-band (1.63um) magnitude 48- 52 F5.3 mag e_Hmag ? Uncertainty in H-band magnitude (4) 54 A1 -- l_H-K [><] indicate upper or lower limits H-K colour index (records 647 to 812 only) (5) 55- 60 F6.3 mag H-K H-K colour index 62- 66 F5.3 mag e_H-K ? Uncertainty in H-K colour index (6)
Note (1): Stars that were not detected in the K-band were assigned K=18.48mag, the detection limit. This is therefore a lower limit to the real K-mag and ">" was added in this case. Note (2): For stars not detected in K-band, no uncertainty can be given and in this case the entry is left blank Note (3): Stars that were not detected in the H-band were assigned H=19.52mag, the detection limit. This is therefore a lower limit to the real H-mag and ">" was added in this case. Note (4): For stars not detected in H-band, no uncertainty can be given and in this case the entry is left blank Note (5): For stars detected only in K- or H-band, the H-K colour is a lower or upper limit, respectively. In this case, ">" or "<" was added. Note (6): For stars with an upper or lower limit for H-K, no uncertainty can be given and in this case the entry is left blank
Acknowledgements: Jan Brand, brand(at)ira.inaf.it
(End) Patricia Vannier [CDS] 21-Dec-2010
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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