MR 2251 – 178: a nearby QSO embedded in a giant H II envelope
MR 2251 – 178: a nearby QSO embedded in a giant H II envelope
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MR 2251 – 178：附近的 QSO 嵌入巨大的 H II 信封中
DOI：
10.1093/mnras/202.1.125
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发表时间：
1983
影响因子：
4.8
通讯作者：
M. Tarenghi
中科院分区：
文献类型：
--
作者：
J. Bergeron;A. Boksenberg;M. Dennefeld;M. Tarenghi
附近的 QSO MR 2251–178 照片显示周围有直径约 27 kpc (H0= 50 km s−1Mpc−1) 的星云。我们对 QSO 和周围场的空间分辨分光光度测量表明，QSO 位于星系的核心，该星系的气态成分具有非常高的电离度、高温 (T= 3 × 104K) 和相对较低的丰度，并且被我们在 [OIII] 发射中观察到的巨大 HII 包络包围。包膜中的电离物质延伸到至少 230 × 60 kpc 的区域，并且与宽带照相底片上明显的任何星云无关；它的速度场类似于观察到的 H 包络线。在 QSO 附近可以看到清晰的旋转模式，速度梯度为 17 km s−1kpc−1out 至 6 kpc。在距 QSO 核较远的地方，即东南方向 50 < r < 170 kpc，旋转曲线是平坦的。 MR 2251−178 在 170 kpc 半径内的总质量为 (1.3 × 1012/sin2i)M⊙。硬辐射能源可以轻松为整个外壳供电。从电离平衡我们得出包络线密度的上限为 0.2 cm−3，电离气体的质量为 2 × 1010<MHII< 5 × 1011M⊙1。 MHII/Mtotalis 比率的上限为 0.25，如果恒星与巨大的包层相关，那么它们在光学上一定非常微弱。我们确认 QSO 位于一小群星系的外围。 HII 包络的质量（观测范围）小于星系团中经常存在的热 X 射线发射气体的质量。第二个背景簇似乎也存在，其红移 z = 0.12。
The nearby QSO MR 2251–178 photographically shows a surrounding nebulosity of diameter ∼27 kpc (H0= 50 km s−1Mpc−1). Our spatially resolved spectrophotometry of the QSO and surrounding field reveals that the QSO lies in the nucleus of a galaxy having a gaseous component of very high ionization, high temperature (T= 3 × 104K) and relatively low abundance and is surrounded by a giant HIIenvelope which we observe in [OIII] emission. The ionized matter in the envelope extends over a region of at least 230 × 60 kpc and is not associated with any nebulosity apparent on broad-band photographic plates; its velocity field resembles those of observed HIenvelopes. A clear rotation pattern is seen close to the QSO with a velocity gradient of 17 km s−1kpc−1out to 6 kpc. At large distances from the QSO nucleus, 50 < r < 170 kpc in the south-east direction, the rotation curve is flat. The total mass of MR 2251−178 within a radius of 170 kpc is (1.3 × 1012/sin2i)M⊙. The hard radiation energy source can easily power the whole envelope. From the ionization equilibrium we derive an upper limit of 0.2 cm−3for the density in the envelope and the mass of ionized gas is 2 × 1010<MHII< 5 × 1011M⊙1. The upper limit on the ratioMHII/Mtotalis 0.25 and if stars are associated with the giant envelope they must be very faint in the optical. We confirm that the QSO lies in the outskirts of a small cluster of galaxies. The mass of the HIIenvelope (observed extent) is smaller than the mass of hot X-ray emitting gas often present in clusters of galaxies. A second, background, cluster seems also to be present, at a redshiftz= 0.12.