arXiv 2212.035632022-12-07astro-ph.GA

近红外弥散星际带的高分辨率研究：小尺度结构、时间变化与恒星特征的搜寻

A high resolution study of near-IR diffuse interstellar bands, search for small scale structure, time variability and stellar features

J. V. Smoker, A. Müller, A. Monreal Ibero, M. Elyajouri, C. J. Evans, F. Najarro, A. Farhang, N. L. J. Cox, J. Minniti, K. T. Smith, J. Pritchard, R. Lallement,… 展开作者

J. V. Smoker, A. Müller, A. Monreal Ibero, M. Elyajouri, C. J. Evans, F. Najarro, A. Farhang, N. L. J. Cox, J. Minniti, K. T. Smith, J. Pritchard, R. Lallement, A. Smette, H. M. J. Boffin, M. Cordiner, J. Cami

备注：: Accepted for publicaion in the main journal of Astronomy and Astrophysics on 25th November 2022
发表信息：: A&A 672, A181 (2023)
DOI：: 10.1051/0004-6361/202142267

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AI总结：

本文利用CRIRES和X-shooter高分辨率光谱研究近红外弥散星际带，测量了1318 nm等多个DIB，分析其与色余、光学DIB及HI/H2的相关性，并搜寻小尺度结构差异和时间变化，未发现显著时间变化。

摘要：

弥散星际带（DIBs）包含星际介质中数百种吸收特征。大多数DIBs在光学波段被观测到，但也有一些位于红外波段。我们使用CRIRES以R=50,000的光谱分辨率和数百的信噪比观测了76颗早型星。我们测量了1318、1527、1561、1565、1567、1574和/或1624 nm附近的DIBs。借助CMFGEN模型，我们共探测到6个DIB特征和17个可能的恒星特征。我们还使用X-shooter对10颗色余E(B-V)在3.2至6.5之间的造父变星以及4颗低水汽条件下的恒星测量了1318 nm和1527 nm处的DIBs。将近红外DIB等值宽度与E(B-V)进行比较，得到0.73至0.96的相关系数；将近红外DIB与光学DIB 5705、5780、6203、6283和6269 Å进行比较时，相关系数r>0.8。5797 Å DIB与近红外DIB的相关性较差。位于9632 Å的“C60+”DIB与1318 nm DIB相关性不佳。我们还确定了以E(B-V)为协变量的偏相关系数。对于早于B2型的恒星，1318 nm DIB在其蓝翼受到一条发射线的影响，该发射线很可能具有恒星本质，尽管我们无法排除星际或星周起源，例如由处于发射状态的DIB所导致。1318 nm DIB具有红翼，并且可以用两个高斯函数较好地拟合。其子成分比值和间距均与5780/5797比值或E(B-V)无相关性。EW(1318 nm)与HI相关，且EW(1318 nm)/E(B-V)随f(H2)增大而减小。在1角分以内的五对恒星显示出相似的1318 nm DIB轮廓。在HD 145501/145502和HD 168607/168625两对恒星中观测到1318 nm的差异。我们分析了17颗间隔6至14个月观测的恒星的CRIRES数据以及两条间隔9.9年观测的X-shooter视线方向数据。在5780、5797 Å、1318 nm或1527 nm DIB中未探测到时间变化。在朝向HD 183143的9577和9632 Å处C60+ DIB中观测到尝试性的时间变化，尽管该变化非常接近噪声水平，仍需进一步确认。

英文摘要：

Diffuse interstellar bands comprise hundreds of absorption features in the ISM. Most DIBs are observed in the optical, but some are in the IR. We observed 76 early-type stars at R=50,000 and S/N ratios of several hundreds using CRIRES. We measure DIBs around 1318, 1527, 1561, 1565, 1567, 1574 and/or 1624 nm. We detect a total of 6 DIB features and 17 likely stellar features assisted by a CMFGEN model. We also measured the DIBs at 1318 and 1527 nm using X-shooter towards ten Ceph. variables with 3.2 < E(B-V) < 6.5 and 4 stars at low values of water vapour. Correlation coeffs. of 0.73-0.96 are found comparing NIRDIB eq. width vs. E(B-V) and with r > 0.8 when comparing the NIR and optical DIBs 5705, 5780, 6203, 6283 and 6269 A. The 5797 A DIB is less well correlated with the NIDIBs. The "C60+" DIB at 9632 A is not well correlated with the 1318 nm DIB. Partial correlation coefficients using E(B-V) as the covariate were also determined. For stars earlier than B2, the 1318 nm DIB is affected by an emission line on its blue wing, likely stellar in nature, although we cannot rule out interstellar/circumstellar origin for example caused by by a DIB in emission. The 1318 nm DIB has a red wing and is reasonably well fitted by two gaussians. Neither the component ratios nor separation are correlated with 5780/5797 or E(B-V). EW(1318 nm) correlates with HI with EW(1318 nm)/E(B-V) decreasing with f(H2). Five pairs of stars within 1 am show similar 1318 nm DIB profiles. Variation in 1318 nm is seen in HD 145501/145502 and HD 168607/168625 pairs. CRIRES data for 17 stars separated by 6-14 months and 2 X-shooter sightlines separated by 9.9 yr were analysed. No time-variability is detected in the 5780, 5797 A, 1318 nm or 1527 nm DIBs. Tentative time variation is observed in the C60+ DIBs at 9577 and 9632 A towards HD 183143 although very close to the noise level with confirmation required.

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摘要：

英文摘要：

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