We present a comprehensive mid-infrared spectroscopic survey of 124 Herbig Ae/Be stars using newly processed Spitzer/IRS spectra from the newly released CASSISjuice database.Based on prominent dust and molecular signa...We present a comprehensive mid-infrared spectroscopic survey of 124 Herbig Ae/Be stars using newly processed Spitzer/IRS spectra from the newly released CASSISjuice database.Based on prominent dust and molecular signatures(polycyclic aromatic hydrocarbons(PAHs),silicates,and hydrogenated amorphous carbons),we classify the stars into five groups.Our analysis reveals that 64%of the spectra show PAH emission,with detections peaking in the stellar effective temperature range 7000–11,000 K(B9–A5).Silicate features appear in 50%of the sample and likewise diminish at higher temperatures.Additionally,we find that future PAH studies can focus on Herbig Ae/Be stars with a spectral index n_(2−24)>−1 and flared morphologies to maximize PAH detections.The 6.2μm PAH band is the most frequently observed in our sample,shifting blueward with increasing stellar temperature,and this is the largest sample yet used to test that peak shift.The weaker 6.0μm feature does not shift with 6.2μm,implying a distinct origin of C=O(carbonyl)or olefinic C=C stretching relative to C–C vibrations.We examined the 11.0/11.2μm PAH ratio using high-resolution Spitzer spectra for the first time in a sample of Herbig Ae/Be stars,finding a range of ionization conditions.This study provides a strong foundation for future JWST observations of intermediate-mass pre-main-sequence stars.展开更多
We present evidences showing that the Be star 3G71, proposed as the optical cou- nterpart of the Be / X-ray binary source 1H2214 + 589, may be a Herbig Ae / Be star. These evidences can be summarized as follows. 1. We...We present evidences showing that the Be star 3G71, proposed as the optical cou- nterpart of the Be / X-ray binary source 1H2214 + 589, may be a Herbig Ae / Be star. These evidences can be summarized as follows. 1. We made spectroscopic observations by using a CCD spectrograph with dispersi- ons 50 A / mm and 195 A / mm at the BAO 2.16m telescope. Analysis of the optical spectra of 3G71 indicates: a. Forbidden lines, such as [OI] 6300 and 6363 A, [FeII] 5527, 4889, 4814, 4415, 4359 and 4304 A, are present in the spectra (Fig.2a, Fig.2b). b. The Hα emission line is unusually strong. Its equivalent width is sometimes more than 100 A (Fig. 1). The photospheric absorption lines of hydrogen are very wide. In the case of Hβ, the distance between two wings amounts to 60 A (Fig.2a, Fig.3). 2. We have performed cross-identification between HST GSC catalogue and IRAS Point Source Catalogue and found the IRAS point souree counterpart of 3G71 to be 2248 + 6058. Its equatorial coordinates (at equinox 1950.0) are 22h24m53s.8 and +60°58′ 15″, while those given by the GSC catalogue are 22h24m53s.37 and +60°58′13″.1. The differences are merely 0.4s and 2″, being less than the uncertainty ellipse (major axis: 11″, minor axis: 6″) given in IRAS PSC. Table 1 lists the flux densities quoted from IRAS GSC and the deduced IRAS IR magnitudes. It is clear from the table that 3G71 has a very large IR color excess, since the V magnitude of 3G71 found from GSC is 12.2 and its V-[25]=+12.47, which is much larger than that expected for classical Be stars and satisfies the criterion for the Herbig Ae / Be stars given by Hu et al., i.e., V-[25] > 7. 3. Using Palomar sky survey map, we have made a search for a nebulosity in the immediate vicinity of 3G71 and actually discovered a bright nebula, at whose center 3G71 is just located. Its diameter is about 1 are-minute. It is concluded from the characteristics of 3G71 mentioned above that 3G71 may be a Herbig Ae / Be star.展开更多
Adobe After Effects软件中经常用到的特效合成插件有Particular、E3D、Form、Plexus等,这些插件各自配备了一套独立的粒子系统。当它们处于同一个合成中时,粒子之间并不会自然融合在一起,而是根据上下图层的关系进行相互遮挡。本文深...Adobe After Effects软件中经常用到的特效合成插件有Particular、E3D、Form、Plexus等,这些插件各自配备了一套独立的粒子系统。当它们处于同一个合成中时,粒子之间并不会自然融合在一起,而是根据上下图层的关系进行相互遮挡。本文深入探讨了不同粒子插件之间相互穿插与遮挡的实现方式,并结合实例阐述制作过程,模拟出两种粒子在同一合成空间中交互融合的逼真效果。展开更多
异常检测是保障飞机运行安全的重要手段,现有的固定阈值异常检测方法对数据时序特征利用较少,提取特征的能力较差。为提高飞机运行安全,提出了一种基于LSTM_AE神经网络的无监督离线异常检测的模型,对实际飞行数据进行异常检测。首先使用...异常检测是保障飞机运行安全的重要手段,现有的固定阈值异常检测方法对数据时序特征利用较少,提取特征的能力较差。为提高飞机运行安全,提出了一种基于LSTM_AE神经网络的无监督离线异常检测的模型,对实际飞行数据进行异常检测。首先使用LSTM(Long Short Term Memory)网络提取正常飞行数据的深度时序特征,再基于AE(Auto Encoder)对提取到的时序特征进行训练,利用模型收敛后得到重构误差确定自适应阈值,最后根据训练好的模型和自适应阈值进行异常检测。试验利用NASA公开的ALFA数据集。结果表明:基于LSTM_AE方法优于传统的固定阈值检测方法,可以实现对异常的检测,准确率为0.8717,召回率为0.9872,F1分数为0.9258。展开更多
基金financial support from CHRIST(Deemed to be University,Bangalore)through the SEED money projects(No:SMSS-2335,11/2023&SMSS-2220,12/2022)by the SERB project(CRG/2023/005271).
文摘We present a comprehensive mid-infrared spectroscopic survey of 124 Herbig Ae/Be stars using newly processed Spitzer/IRS spectra from the newly released CASSISjuice database.Based on prominent dust and molecular signatures(polycyclic aromatic hydrocarbons(PAHs),silicates,and hydrogenated amorphous carbons),we classify the stars into five groups.Our analysis reveals that 64%of the spectra show PAH emission,with detections peaking in the stellar effective temperature range 7000–11,000 K(B9–A5).Silicate features appear in 50%of the sample and likewise diminish at higher temperatures.Additionally,we find that future PAH studies can focus on Herbig Ae/Be stars with a spectral index n_(2−24)>−1 and flared morphologies to maximize PAH detections.The 6.2μm PAH band is the most frequently observed in our sample,shifting blueward with increasing stellar temperature,and this is the largest sample yet used to test that peak shift.The weaker 6.0μm feature does not shift with 6.2μm,implying a distinct origin of C=O(carbonyl)or olefinic C=C stretching relative to C–C vibrations.We examined the 11.0/11.2μm PAH ratio using high-resolution Spitzer spectra for the first time in a sample of Herbig Ae/Be stars,finding a range of ionization conditions.This study provides a strong foundation for future JWST observations of intermediate-mass pre-main-sequence stars.
文摘We present evidences showing that the Be star 3G71, proposed as the optical cou- nterpart of the Be / X-ray binary source 1H2214 + 589, may be a Herbig Ae / Be star. These evidences can be summarized as follows. 1. We made spectroscopic observations by using a CCD spectrograph with dispersi- ons 50 A / mm and 195 A / mm at the BAO 2.16m telescope. Analysis of the optical spectra of 3G71 indicates: a. Forbidden lines, such as [OI] 6300 and 6363 A, [FeII] 5527, 4889, 4814, 4415, 4359 and 4304 A, are present in the spectra (Fig.2a, Fig.2b). b. The Hα emission line is unusually strong. Its equivalent width is sometimes more than 100 A (Fig. 1). The photospheric absorption lines of hydrogen are very wide. In the case of Hβ, the distance between two wings amounts to 60 A (Fig.2a, Fig.3). 2. We have performed cross-identification between HST GSC catalogue and IRAS Point Source Catalogue and found the IRAS point souree counterpart of 3G71 to be 2248 + 6058. Its equatorial coordinates (at equinox 1950.0) are 22h24m53s.8 and +60°58′ 15″, while those given by the GSC catalogue are 22h24m53s.37 and +60°58′13″.1. The differences are merely 0.4s and 2″, being less than the uncertainty ellipse (major axis: 11″, minor axis: 6″) given in IRAS PSC. Table 1 lists the flux densities quoted from IRAS GSC and the deduced IRAS IR magnitudes. It is clear from the table that 3G71 has a very large IR color excess, since the V magnitude of 3G71 found from GSC is 12.2 and its V-[25]=+12.47, which is much larger than that expected for classical Be stars and satisfies the criterion for the Herbig Ae / Be stars given by Hu et al., i.e., V-[25] > 7. 3. Using Palomar sky survey map, we have made a search for a nebulosity in the immediate vicinity of 3G71 and actually discovered a bright nebula, at whose center 3G71 is just located. Its diameter is about 1 are-minute. It is concluded from the characteristics of 3G71 mentioned above that 3G71 may be a Herbig Ae / Be star.
文摘Adobe After Effects软件中经常用到的特效合成插件有Particular、E3D、Form、Plexus等,这些插件各自配备了一套独立的粒子系统。当它们处于同一个合成中时,粒子之间并不会自然融合在一起,而是根据上下图层的关系进行相互遮挡。本文深入探讨了不同粒子插件之间相互穿插与遮挡的实现方式,并结合实例阐述制作过程,模拟出两种粒子在同一合成空间中交互融合的逼真效果。
文摘异常检测是保障飞机运行安全的重要手段,现有的固定阈值异常检测方法对数据时序特征利用较少,提取特征的能力较差。为提高飞机运行安全,提出了一种基于LSTM_AE神经网络的无监督离线异常检测的模型,对实际飞行数据进行异常检测。首先使用LSTM(Long Short Term Memory)网络提取正常飞行数据的深度时序特征,再基于AE(Auto Encoder)对提取到的时序特征进行训练,利用模型收敛后得到重构误差确定自适应阈值,最后根据训练好的模型和自适应阈值进行异常检测。试验利用NASA公开的ALFA数据集。结果表明:基于LSTM_AE方法优于传统的固定阈值检测方法,可以实现对异常的检测,准确率为0.8717,召回率为0.9872,F1分数为0.9258。
