Deep intermediate-band surface photometry of NGC 907

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題名:	Deep intermediate-band surface photometry of NGC 907
作者:	Zheng,ZY;Shang,ZH;Su,HJ;Burstein,D;Chen,JS;Deng,ZG;Byun,YI;Chen,R;Chen,WP;Deng,LC;Fan,XH;Fang,LZ;Hester,JJ;Jiang,ZJ;Li,Y;Lin,WP;Sun,WH;Tsay,WS;Windhorst,RA;Wu,H;Xia,XY;Xu,W;Xue,SJ;Yan,HJ;Zheng,Z;Zhou,X;Z
貢獻者:	天文研究所
關鍵詞:	SPIRAL GALAXY NGC5907;STELLAR PHOTOMETRY;NGC-5907;HALO;LIGHT;SPECTROPHOTOMETRY;DISKS
日期:	1999
上傳時間:	2010-06-29 19:35:39 (UTC+8)
出版者:	中央大學
摘要:	Intrigued by the initial report of an extended luminosity distribution perpendicular to the disk of the edge-on Sc galaxy NGC 5907, we have obtained very deep exposures of this galaxy with a Schmidt telescope, large-format CCD, and intermediate-band filters centered at 6660 Angstrom and 8020 Angstrom. These two filters, part of a 15-filter set, are custom designed to avoid the brightest (and most variable) night skylines. As a result, our images are able to go deeper with lower sky noise than those taken with broadband filters at similar effective wavelengths: e.g., 0.6 e(-) arcsec(-2) s(-1) for our observations versus 7.4 e(-) arcsec(-2) s(-1) for the R-band measures of Morrison et al. In our assessment of both random and systematic errors, we show that the flux level where the errors of observation reach 1 mag arcsec(-2) are 29.00 mag arcsec(-2) in the 6660 Angstrom image (corresponding to 28.7 in the R band) and 27.4 mag arcsec(-2) in the 8020 Angstrom image (essentially on the I-band system). In a previous paper we have shown that NGC 5907 has a luminous ring around it, most plausibly caused by the tidal disruption of a dwarf spheroidal galaxy by the much more massive spiral. Here we show that, for values fainter than 27 R mag arcsec(-2), the surface brightness around NGC 5907 is strongly asymmetric, being mostly brighter on the northwest (ring) side of the galactic midplane. This asymmetry rules out a halo as the cause of the faint surface brightness we see. We find this asymmetry is likely an artifact resulting from a combination of ring light and residual surface brightness at faint levels from stars that our star-masking procedure cannot completely eliminate. The possible existence of an optical face-on warp in NGC 5907, suggested by our Very Large Array H I observations, is too confused with foreground star contamination to be independently studied. Good agreement with the surface photometry of NGC 5907 by other observers leads us to conclude that their data are similarly affected at faint levels by ring light and the residual effects of star masking procedures. Inspection of published images confirm this to be the case. Thus, we conclude that NGC 5907 does not have a faint extended halo.
關聯:	ASTRONOMICAL JOURNAL
顯示於類別:	[天文研究所] 期刊論文

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