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Analysis of the possible satellite contamination in LAMOST-MRS spectra

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arXiv 2023年

作者： Kovalev, Mikhail Hainaut, Olivier R. Chen, Xuefei Han, Zhanwen Yunnan Observatories China Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China Sternberg Astronomical Institute of the M. V. Lomonosov Moscow State University Leninskie Gory Moscow119992 Russia European Southern Observatory Karl-Schwarzschild-Straße 2 Garching bei München85748 Germany Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China

We present the detection of false positive double-lined spectroscopic binaries candidates (SB2) using medium-resolution survey (MRS) spectra from the one time-domain field of LAMOST data release 10 (DR10). The secondary component in all these binaries has near zero radial velocity and solar-like spectral lines. Highly likely this is light from the semi-transparent clouds illuminated by the full Moon. However we also suspect that partially this contamination can be caused by a solar light reflected from the surface of low-orbital artificial satellites launched in the beginning of 2022. We found several possible contaminant candidates using archival orbital data. We propose measures to reduce risk of such contamination for the future observations and methods to find it in archived ones. Copyright © 2023, The Authors. All rights reserved.

关键词： Contamination

The 2175 Å~ Bump Features in FeLoBAL Quasars: One Indicator of MW-like Dust in the Nuclear Region of Quasar

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arXiv 2022年

作者： Zhang, Shaohua Ge, Jian Ji, Tuo Jiang, Peng Luo, Zhijian Pan, Xiang Shi, Xiheng Shu, Chenggang Wang, Jianguo Xiao, Hubing Zhou, Hongyan Shanghai Key Lab for Astrophysics Shanghai Normal University Shanghai200234 China Key Laboratory for Research in Galaxies and Cosmology Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai200030 China Key Laboratory of Polar Science Polar Research Institute of China Ministry of Natural Resources Shanghai200136 China Key Laboratory for the Structure and Evolution of Celestial Objects Yunnan Observatories Chinese Academy of Sciences Yunnan Kunming650011 China Key Laboratory for Research in Galaxies and Cosmology Department of Astronomy University of Science and Technology of China Chinese Academy of Sciences Anhui Hefei230026 China School of Astronomy and Space Science University of Science and Technology of China Anhui Hefei230026 China

To investigate the properties of dust in the nuclear region of quasars, we explored the extinction curves of the iron low-ionization broad absorption line (FeLoBAL) quasar SDSS J163004.29+311957.6 and its two analogues. The parameterized extinction curves indicated the Milky Way-like 2175 Å bump features in underlying extinction, which are similar to those seen in the Local Group and a subset of high-redshift star-forming galaxies. Compared to the bump features in the Large Magellanic Clouds (LMC), the detections in this work are much closer to those in the Milky Way (MW). These bump features, as well as those in the high- and low-ionization broad absorption line (BAL) quasars of Zhang et al., are probably the counterpart of the 2175 Å bump features in the quasar environment. This type of dust grain is generally small, easily disrupted by high-energy photons and has difficulty surviving in the radiation field of the active galactic nucleus (AGN). However, due to the presence of absorption-line outflows, the 2175 Å bump feature in quasars, which should be rare, is seen many times in BAL quasars. The shielding effect of outflow clouds allows the MW-like dust grains to be assembled or extends the survival period in the quasar nuclear region. The process, and physical and chemical conditions deserve further observational study and investigation. © 2022, CC BY.

关键词： Dust

WD+AGB star systems as the progenitors of type Ia supernovae

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Proceedings of the International Astronomical Union 2019年第S343期14卷 540-541页

作者： Wang B. Yunnan Observatories Chinese Academy of Sciences Kunming 650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650216 China

WD+AGB star systems have been suggested as an alternative way for producing type Ia supernovae (SNe Ia), known as the core-degenerate (CD) scenario. In the CD scenario, SNe Ia are produced at the final phase during the evolution of common-envelope through a merger between a carbon-oxygen (CO) WD and the CO core of an AGB secondary. However, the rates of SNe Ia from this scenario are still uncertain. In this work, I carried out a detailed investigation on the CD scenario based on a binary population synthesis approach. I found that the Galactic rates of SNe Ia from this scenario are not more than 20% of total SNe Ia due to more careful treatment of mass transfer, and that their delay times are in the range of â'1/490-2500 Myr, mainly contributing to the observed SNe Ia with short and intermediate delay times. © International Astronomical Union 2019.

关键词： Binaries: Close Supernovae: General White dwarfs

Can small-scale magnetic fields be the major cause for the near-surface effect of the solar p-mode frequencies?

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arXiv 2021年

作者： Li, Yan Zhang, Qian-Sheng Wu, Tao Su, Jie Chen, Xing-Hao Lin, Gui-Fang Guo, Jian-Heng Liu, Jie-Ying Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Center for Astronomical Mega-Science Chinese Academy of Sciences Beijing100012 China University of Chinese Academy of Sciences Beijing100049 China

Small-scale magnetic fields are not only the fundamental element of the solar magnetism, but also closely related to the structure of the solar atmosphere. The observations have shown that there is a ubiquitous tangled small-scale magnetic field with a strength of 60 ∼ 130 G in the canopy forming layer of the quiet solar photosphere. On the other hand, the multi-dimensional MHD simulations show that the convective overshooting expels the magnetic field to form the magnetic canopies at a height of about 500 km in the upper photosphere. However, the distribution of such small-scale "canopies" in the solar photosphere cannot be rigorously constrained by either observations and numerical simulations. Based on stellar standard models, we identify that these magnetic canopies can act as a global magnetic-arch splicing layer, and find that the reflections of the solar p-mode oscillations at this magnetic-arch splicing layer results in significant improvement on the discrepancy between the observed and calculated p-mode frequencies. The location of the magnetic-arch splicing layer is determined at a height of about 630 km, and the inferred strength of the magnetic field is about 90 G. These features of the magnetic-arch splicing layer derived independently in the present study are quantitatively in agreement with the presence of small-scale magnetic canopies as those obtained by the observations and 3-D MHD simulations. © 2021, CC BY.

关键词： Arches

The Common Envelope evolution Outcome. II. Short Orbital Period Hot Subdwarf B Binaries Reveal a Clear Picture

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arXiv 2023年

作者： Ge, Hongwei Tout, Christopher A. Webbink, Ronald F. Chen, Xuefei Sarkar, Arnab Li, Jiao Li, Zhenwei Zhang, Lifu Han, Zhanwen Yunnan Observatories Chinese Academy of Sciences 396 YangFangWang Guandu District Kunming650216 China Key Laboratory for Structure and Evolution of Celestial Objects Chinese Academy of Sciences P.O. Box 110 Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China Institute of Astronomy The Observatories University of Cambridge Madingley Road CambridgeCB3 0HA United Kingdom University of Illinois at Urbana-Champaign 1002 W Green St Urbana61801 United States Key Lab of Space Astronomy and Technology National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China University of Chinese Academy of Sciences Beijing100049 China

Common envelope evolution (CEE) is vital to form short orbital period compact binaries. It covers many objects, such as double compact merging binaries, type Ia supernovae progenitors, binary pulsars and X-ray binaries. Knowledge of the common envelope (CE) ejection efficiency still needs to be improved, though progress has been made recently. Short orbital period hot subdwarf B star (sdB) plus white dwarf (WD) binaries are the most straightforward samples with which to constrain CEE physics. We apply the known orbital period–white dwarf mass relation to constrain the sdB progenitors of seven sdB+WD binaries with a known inclination angle. The average CE efficiency parameter is 0.32. This is consistent with previous studies. However, the CE efficiency need not be constant but a function of the initial mass ratio based on well-constrained sdB progenitor mass and evolutionary stage. Our results can be used as physical inputs for binary population synthesis simulations of related objects. A similar method can also be applied to study other short orbital period WD binaries. Copyright © 2023, The Authors. All rights reserved.

关键词： White dwarfs

BayeSED-GALAXIES I. Performance test for simultaneous photometric redshift and stellar population parameter estimation of galaxies in the CSST wide-field multiband imaging survey

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arXiv 2023年

作者： Han, Yunkun Fan, Lulu Zheng, Xian Zhong Bai, Jin-Ming Han, Zhanwen Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China Deep Space Exploration Laboratory Department of Astronomy University of Science and Technology of China Hefei230026 China School of Astronomy and Space Science University of Science and Technology of China Hefei230026 China Purple Mountain Observatory Chinese Academy of Sciences 10 Yuanhua Road Nanjing210023 China

The forthcoming CSST wide-field multiband imaging survey will produce seven-band photometric spectral energy distributions (SEDs) for billions of galaxies. The effective extraction of astronomical information from these massive datasets of SEDs relies on the techniques of both SED synthesis (or modeling) and analysis (or fitting). We evaluate the performance of the latest version of BayeSED code combined with SED models with increasing complexity for simultaneously determining the photometric redshifts and stellar population parameters of galaxies in this survey. By using an empirical statistics-based mock galaxy sample without SED modeling errors, we show finding that the random observational errors in photometries are more important sources of errors than the parameter degeneracies and Bayesian analysis method and tool. By using a Horizon-AGN hydrodynamical simulation-based mock galaxy sample with SED modeling errors about the star formation histories (SFHs) and dust attenuation laws (DALs), the simple typical assumptions lead to significantly worse parameter estimation with CSST photometries *** SED models with more flexible (or complicated) forms of SFH/DAL do not necessarily lead to better estimation of redshift and stellar population parameters. We discuss the selection of the best SED model by means of Bayesian model comparison in different surveys. Our results reveal that the Bayesian model comparison with Bayesian evidence may favor SED models with different complexities when using photometries from different surveys. Meanwhile, the SED model with the largest Bayesian evidence tends to give the best performance of parameter estimation, which is more clear for photometries with larger discriminative power. Copyright © 2023, The Authors. All rights reserved.

关键词： Galaxies

Signatures of a surviving helium-star companion in Type Ia supernovae and constraints on the progenitor companion of SN 2011fe

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arXiv 2022年

作者： Liu, Zheng-Wei Röpke, Friedrich K. Zeng, Yaotian 396 Yangfangwang Guandu District Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming650216 China University of Chinese Academy of Science Beijing100012 China Zentrum für Astronomie Universität Heidelberg Institut für Theoretische Astrophysik Philosophenweg 12 Heidelberg 69120 Germany Heidelberger Institut für Theoretische Studien Schloss-Wolfsbrunnenweg 35 Heidelberg 69118 Germany

Single-degenerate (SD) binary systems composed of a white dwarf and a non-degenerate helium (He)-star companion have been proposed as the potential progenitors of Type Ia supernovae (SNe Ia). The He-star companions are expected to survive the SN Ia explosion in this SD progenitor model. In the present work, we map the surviving He-star companion models computed from our previous three-dimensional hydrodynamical simulations of ejecta-companion interaction into the one-dimensional stellar evolution code Modules for Experiments in Stellar Astrophysics (MESA) to follow their long-term evolution to make predictions on their post-impact observational properties, which can be helpful for searches of such surviving He-star companions in future observations. By comparing with the very late-epoch light curve of the best observed SN Ia, SN 2011fe, we find that our surviving He-star companions become significantly more luminous than SN 2011fe about 1000 d after the maximum light. This suggests that a He star is very unlikely to be a companion to the progenitor of SN 2011fe. Copyright © 2022, The Authors. All rights reserved.

关键词： Helium

Magnetic topologies of two weak-line T Tauri stars TAP 4 and TAP 40

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arXiv 2023年

作者： Xiang, Yue Gu, Shenghong Donati, J.-F. Hussain, G.A.J. Cameron, A. Collier Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing101408 China IRAP Université de Toulouse CNRS UPS CNES ToulouseF-31400 France Keplerlaan 1 NoordwijkNL-2201AZ Netherlands School of Physics and Astronomy University of St Andrews Fife KY16 9SS United Kingdom

We present a Zeeman-Doppler imaging study of two weak-line T Tauri stars TAP 4 and TAP 40, based on the high-resolution spectropolarimetric observations with ESPaDOnS at the Canada-France-Hawaii Telescope in November 2013, in the framework of the MaTYSSE large programme. We apply two Zeeman-Doppler imaging codes to the Stokes I and V profiles to reconstruct their brightness and large-scale magnetic field images. The results given by the two imaging codes are in good agreement with each other. TAP 4 shows a large polar cool spot and several intermediate-latitude warm spots on its surface, whereas TAP 40 exhibits very weak variations in its Stokes I profiles suggesting a mostly unspotted photosphere. We detect Zeeman signatures in the Stokes V profiles of both stars. The reconstructed magnetic maps reveal dominantly toroidal fields, which enclose about 60 per cent of the total magnetic energy for both of TAP 4 and TAP 40. Both stars show prominent circular ring features of the azimuthal magnetic field. We derive a solar-like surface differential rotation on TAP 4 from the tomographic modelling. The brightness image of TAP 4 is used to predict the radial velocity jitters induced by its activity. After filtering out the activity jitter, the RMS of its RVs is reduced from 1.7 km s−1 to 0.2 km s−1, but we do not detect any periodic signals in the filtered RVs of TAP 4, implying that it is unlikely to host a close-in exoplanet more massive than ∼3.5 MJup at 0.1 au. Copyright © 2023, The Authors. All rights reserved.

关键词： Luminance

On the Origin of the Strong Optical Variability of Emission-line Galaxies

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arXiv 2022年

作者： Lin, Ruqiu Zheng, Zhen-Ya Hu, Weida Jiang, Chunyan Pan, Xiang Yang, Chenwei Yuan, Fang-Ting Rahna, P.T. Wang, Jian-Guo Wang, Yibo Jiang, Ning Zhu, Shuairu Key Laboratory for Research in Galaxies and Cosmology Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China School of Astronomy and Space Sciences University of Chinese Academy of Sciences No. 19A Yuquan Road Beijing100049 China CAS Key Laboratory for Research in Galaxies and Cosmology Department of Astronomy University of Science and Technology of China Anhui Hefei230026 China Key Laboratory for Polar Science MNR Polar Research Institute of China 451 Jinqiao Road Shanghai200136 China Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming650216 China

Emission-line galaxies (ELGs) are crucial in understanding the formation and evolution of galaxies, while little is known about their variability. Here we report the study on the optical variability of a sample of ELGs selected in the COSMOS field, which has narrow-band observations in two epochs separated by 12 years. This sample was observed with Suprime-Cam (SC) and Hyper Suprime-Cam (HSC) on the Subaru telescope in NB816 and i'/i bands, respectively. After carefully removing the wing effect of a narrow-band filter, we check the optical variability in a sample of 181 spectroscopically confirmed ELGs. We find that 0 (0/68) Hα emitters, 11.9% (5/42) [O iii] emitters, and 0 (0/71) [O ii] emitters show significant variability (|∆mNB| ≥ 3 σ∆mNB,AGN = 0.20 mag) in the two-epoch narrow-band observations. We investigate the presence of active galactic nucleus (AGN) in this variable ELG (var-ELG) sample with three methods, including X-ray luminosity, mid-infrared activity, and radio-excess. We find zero bright AGN in this var-ELG sample, but cannot rule out the contribution from faint AGN. We find that SNe could also dominate the variability of the var-ELG sample. The merger morphology shown in the HST/F814W images of all the var-ELG sample is in agreement with the enhancement of star formation, i.e., the SNe activity. © 2022, CC BY.

关键词： Galaxies