GALACTICNUCLEUS: A high angular resolution $JHK_s$ imaging survey of the Galactic Centre. I. Methodology, performance, and near-infrared extinction towards the Galactic Centre
F. Nogueras-Lara, A. T. Gallego-Calvente, H. Dong, E. Gallego-Cano, J. H. V. Girard, M. Hilker, P. T. de Zeeuw, A. Feldmeier-Krause, S. Nishiyama, F. Najarro, R. Schödel
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Updated to the final version published in Astronomy & Astrophysics. 23 pages, 35 figures, 3 appendices
The Galactic Centre is of fundamental astrophysical interest, but existing near-infrared surveys fall short to cover it adequately. We introduce the GALACTICNUCLEUS survey, a $JHK_s$ imaging survey of the centre of the Milky Way with a $0.2"$ angular resolution. We present the observations of Field 1 of our survey, centred approximately on SgrA* with an approximate size of $7.95'\times3.43'$. We describe the observational set-up and data reduction pipeline and discuss the quality of the data. Finally, we present some preliminary analysis of the data. The data were acquired with the near-infrared camera HAWK-I at the ESO VLT. Short readout times in combination with the speckle holography algorithm allowed us to produce final images with a stable, Gaussian PSF of $0.2"$ FWHM. Astrometric calibration is achieved via the VVV survey and photometric calibration is based on the SIRIUS/IRSF survey. The quality of the data is assessed by comparison between observations of the same field with different detectors of HAWK-I and at different times. We reach 5 sigma detection limits of approximately $J=22$, $H=21$, and $K_s=20$. The photometric uncertainties are less than 0.05 at $J<20$, $H<17$ and $K_s<16$. We distinguish five stellar populations in the colour-magnitude diagrams; three of them appear to belong to foreground spiral arms, and the other two correspond to a high- and a low-extinction star groups at the Galactic Centre. We use our data to analyse the near-infrared extinction curve and conclude that it can be described very well by a power-law with an index of $JHK_s=2.30\pm0.08$. We do not find any evidence that this index depends on the position along the line-of-sight, or on the absolute value of the extinction. We produce extinction maps that show the clumpiness of the ISM at the Galactic Centre. Finally, we estimate that the majority of the stars have solar or super-solar metallicity.
GALACTICNUCLEUS: A high angular resolution JHKs imaging survey of the Galactic centre. V. Toward the GNS Second Data Release: Methodology, Photometric and Astrometric Performance
Instituto de Astrofísica de Andalucía (CSIC)（安达卢西亚天体物理学研究所）；Laboratoire d’Astrophysique de Bordeaux (LAB), Université de Bordeaux（波尔多大学天体物理实验室）
GALACTICNUCLEUS: A high-angular-resolution JHKs imaging survey of the Galactic centre III. Evidence for wavelength dependence of the extinction curve in the near-infrared
GALACTICNUCLEUS: A high-angular-resolution JHKs imaging survey of the Galactic centre II. First data release of the catalogue and the most detailed CMDs of the GC
Interstellar Extinction Law toward the Galactic Center III: J, H, Ks bands in the 2MASS and the MKO systems, and 3.6, 4.5, 5.8, 8.0 micron in the Spitzer/IRAC system
Young stars and reflection nebulae near the lower "edge" of the Galactic molecular disc
我们研究了发生在银河平面以下朝向光学反射星云ESO 368-8（IRAS 07383-3325）的区域中的恒星形成。我们确认存在一个小的年轻星团（或数十个YSO的聚集体），嵌入在位于银河系圆盘较低“边缘”附近的分子云中，并将年轻的恒星星族排除在外。我们报告了一个近红外星云的发现，并提出了一个CO地图揭示了一个新的密集，动态云核心。我们使用近红外JHKs图像，毫米CO光谱和光学V波段图像。这个恒星形成区显示了一个光学反射星云（ESO 368-8）和一个近红外星云，它们之间的距离约为46”（1.1 pc）。这两个星云很可能是同时代的，代表了同一个恒星形成时期的两种表现，年龄大约为100万年。近红外星云揭示了一个嵌入式的，光学和近红外不可见的光源，其光散射了由以前的恒星喷流或分子流出所雕刻的空腔，并进入我们的视线。分子云完全被我们的CO（J=1-0）图所覆盖，由这条线追踪，它延伸到7.8 x 7.8 pc ^2的区域，显示出5.4' x 5.4'的角尺寸和类似于球形（或稍微彗星状）的球状体的形状（接近圆形）。朝向近红外星云的方向，分子云包含一个致密的核心，其中分子气体显示出大的线宽，表明一个非常动态的状态，具有搅拌气体和超音速运动。我们估计这个区域的分子气体质量在600到1600个太阳质量之间。光学反射星云和近红外星云的消光Av分别为3-4等和12-15等。
