Pub Date : 2023-01-01DOI: 10.25518/0037-9565.11286
Antoine THUILLIER, Valérie VAN GROOTEL, Francisco J. POZUELOS, Martín DÉVORA-PAJARES, Stéphane CHARPINET, Lionel SIESS
Hot subdwarf stars are small post-red-giant-branch stars. To this day, no planets have been confirmed around them. In this document we present the first results of our analysis to quantify the presence of planets around hot subdwarfs by performing a wide transit survey using photo-metric data from the first part of the mission TESS. Our work shows an absence of transiting planets for the majority of these stars, but some display potentially interesting signals. These are now observed in our follow-up procedure. We also compute upper limits of the occurrence rates for planets around hot subdwarf stars from the numerous stars displaying no signal.
{"title":"A transit survey to search for planets around hot subdwarfs","authors":"Antoine THUILLIER, Valérie VAN GROOTEL, Francisco J. POZUELOS, Martín DÉVORA-PAJARES, Stéphane CHARPINET, Lionel SIESS","doi":"10.25518/0037-9565.11286","DOIUrl":"https://doi.org/10.25518/0037-9565.11286","url":null,"abstract":"Hot subdwarf stars are small post-red-giant-branch stars. To this day, no planets have been confirmed around them. In this document we present the first results of our analysis to quantify the presence of planets around hot subdwarfs by performing a wide transit survey using photo-metric data from the first part of the mission TESS. Our work shows an absence of transiting planets for the majority of these stars, but some display potentially interesting signals. These are now observed in our follow-up procedure. We also compute upper limits of the occurrence rates for planets around hot subdwarf stars from the numerous stars displaying no signal.","PeriodicalId":35838,"journal":{"name":"Bulletin de la Societe Royale des Sciences de Liege","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135053205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.25518/0037-9565.11220
Isaac D. LOPEZ, Alekzander KOSAKOWSKI, Brad N. BARLOW, Thomas KUPFER
We present a search for new variable hot subdwarfs from Gaia eDR3 using the Zwicky Transient Facility DR9 and the 2.1 m Otto Struve Telescope at McDonald Observatory. We report the discovery of 22 HW Vir binaries, 24 reflection effect binaries, and 14 ellipsoidally modulated systems. Candidate selection for our high-speed observations was based on object location on the Gaia color-magnitude diagram and on intrinsic variability, which we estimate from the Gaia G flux uncertainties. Notable discoveries include a candidate 72 min period sdB+WD binary and two short period HW Vir binaries with periods around 67 min and 79 min, which includes the shortest-period eclipsing sdB+dM/BD discovered to date.
{"title":"New Hot Subdwarf Variables from Gaia eDR3","authors":"Isaac D. LOPEZ, Alekzander KOSAKOWSKI, Brad N. BARLOW, Thomas KUPFER","doi":"10.25518/0037-9565.11220","DOIUrl":"https://doi.org/10.25518/0037-9565.11220","url":null,"abstract":"We present a search for new variable hot subdwarfs from Gaia eDR3 using the Zwicky Transient Facility DR9 and the 2.1 m Otto Struve Telescope at McDonald Observatory. We report the discovery of 22 HW Vir binaries, 24 reflection effect binaries, and 14 ellipsoidally modulated systems. Candidate selection for our high-speed observations was based on object location on the Gaia color-magnitude diagram and on intrinsic variability, which we estimate from the Gaia G flux uncertainties. Notable discoveries include a candidate 72 min period sdB+WD binary and two short period HW Vir binaries with periods around 67 min and 79 min, which includes the shortest-period eclipsing sdB+dM/BD discovered to date.","PeriodicalId":35838,"journal":{"name":"Bulletin de la Societe Royale des Sciences de Liege","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135052360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.25518/0037-9565.11305
Weikai ZONG, Stéphane CHARPINET, Gérard VAUCLAIR, Jian-Ning FU, Xiao-Yu MA
We briefly review progress in developing a pathway to nonlinear astereoseismology, both from theoretical and observational aspects. As predicted by the theory of weak nonlinear interactions between resonant modes, their amplitude and frequency can be modulated according to vari-ous kinds of patterns. However, those subtle modulations could hardly be well characterized from ground-based photometric monitoring. The Kepler spacecraft offered a new window to find clear-cut evidence of well-determined amplitude and frequency modulations, leading to the first discoveries of such variations in pulsating white dwarf and hot B subdwarf stars. Fol-lowing that direction, a systematic survey of oscillation mode properties in compact pulsators monitored by Kepler suggests that mode variability is likely a common phenomenon, which remain unaccounted for by standard linear non-radial pulsation theory. To reach this conclusion firmly, the survey has now been extended to a larger context including compact stars observed by K2 and TESS. We expect that this extended survey will help to constrain key parameters governing weak nonlinear effects in stellar oscillations.
{"title":"The cradle of nonlinear asteroseismology: observations of oscillation mode variability in compact pulsating stars","authors":"Weikai ZONG, Stéphane CHARPINET, Gérard VAUCLAIR, Jian-Ning FU, Xiao-Yu MA","doi":"10.25518/0037-9565.11305","DOIUrl":"https://doi.org/10.25518/0037-9565.11305","url":null,"abstract":"We briefly review progress in developing a pathway to nonlinear astereoseismology, both from theoretical and observational aspects. As predicted by the theory of weak nonlinear interactions between resonant modes, their amplitude and frequency can be modulated according to vari-ous kinds of patterns. However, those subtle modulations could hardly be well characterized from ground-based photometric monitoring. The Kepler spacecraft offered a new window to find clear-cut evidence of well-determined amplitude and frequency modulations, leading to the first discoveries of such variations in pulsating white dwarf and hot B subdwarf stars. Fol-lowing that direction, a systematic survey of oscillation mode properties in compact pulsators monitored by Kepler suggests that mode variability is likely a common phenomenon, which remain unaccounted for by standard linear non-radial pulsation theory. To reach this conclusion firmly, the survey has now been extended to a larger context including compact stars observed by K2 and TESS. We expect that this extended survey will help to constrain key parameters governing weak nonlinear effects in stellar oscillations.","PeriodicalId":35838,"journal":{"name":"Bulletin de la Societe Royale des Sciences de Liege","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135052649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.25518/0037-9565.11205
Ulrich HEBER, collaboration MUCHFUSS
Hyper-velocity stars (HVS) are enigmatic objects because they are travelling so fast that they escape from the Galaxy. Among hot subdwarfs, only one such star is known, the He-sdO US 708. The Hyper-MUCHFUSS collaboration provided additional HVS candidates. Here we revisit the fastest candidates including US 708 by analysing optical spectra and spectral energy distributions using a new grid of tailored model atmospheres and report preliminary results. The sample is dominated by H-rich subdwarfs and their distribution in the Kiel diagram appears to be bimodal for the sdB stars but otherwise fits canonical evolutionary models well. Gaia’s proper motion measurements allowed a precise kinematic investigation to be made. It turns out that all previously proposed HVS candidates are actually bound to the Galaxy, except US 708. The original candidate sample turns out to belong to an extreme halo population. The scarcity of available observations of US 708 calls for space-based UV and IR photometry as well as high precision radial velocity measurements.
超高速恒星(HVS)是一种神秘的天体，因为它们的运动速度非常快，以至于它们逃离了银河系。在热亚矮星中，只有一颗这样的恒星是已知的，那就是He-sdO US 708。Hyper-MUCHFUSS合作提供了额外的HVS候选物。在这里，我们重新审视了最快的候选者，包括US 708，通过分析光谱和光谱能量分布，使用一个新的定制模式大气网格，并报告了初步结果。样本中主要是富氢的亚矮星，它们在基尔图中的分布对sdB恒星来说似乎是双峰的，但在其他方面很符合标准的演化模型。盖亚的适当运动测量允许进行精确的运动学调查。事实证明，除了US 708之外，所有之前提出的HVS候选者实际上都与银河系有关。原来的候选样本属于一个极端晕群。由于US 708观测资料的缺乏，需要进行基于空间的紫外和红外测光以及高精度径向速度测量。
{"title":"The fastest hot subdwarfs revisited","authors":"Ulrich HEBER, collaboration MUCHFUSS","doi":"10.25518/0037-9565.11205","DOIUrl":"https://doi.org/10.25518/0037-9565.11205","url":null,"abstract":"Hyper-velocity stars (HVS) are enigmatic objects because they are travelling so fast that they escape from the Galaxy. Among hot subdwarfs, only one such star is known, the He-sdO US 708. The Hyper-MUCHFUSS collaboration provided additional HVS candidates. Here we revisit the fastest candidates including US 708 by analysing optical spectra and spectral energy distributions using a new grid of tailored model atmospheres and report preliminary results. The sample is dominated by H-rich subdwarfs and their distribution in the Kiel diagram appears to be bimodal for the sdB stars but otherwise fits canonical evolutionary models well. Gaia’s proper motion measurements allowed a precise kinematic investigation to be made. It turns out that all previously proposed HVS candidates are actually bound to the Galaxy, except US 708. The original candidate sample turns out to belong to an extreme halo population. The scarcity of available observations of US 708 calls for space-based UV and IR photometry as well as high precision radial velocity measurements.","PeriodicalId":35838,"journal":{"name":"Bulletin de la Societe Royale des Sciences de Liege","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135052915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.25518/0037-9565.11131
Michel Blondieau, Frédéric Hatert, Stéphane Puccio, Martin Depret, Fabrice Dal Bo
Des filons plombifères à gangue baritée sont observés dans la région de Martelange et notamment à Wisembach dans la formation de Villé, une formation du Dévonien inférieur (Praguien) connue pour être traversée par de nombreux filons plombifères. La présence de barite dans ces filons est cependant atypique pour l’Ardenne belge, et cette observation semble indiquer une origine commune entre ces filons et ceux de la région de Vianden au Grand-duché de Luxembourg. La minéralogie des filons de Wisembach se résume à quelques espèces primaires et à des espèces supergènes, avec notamment la romanèchite, un oxyde de manganèse contenant du baryum dont la première occurrence belge est signalée ici. Le cadre structural, notamment les failles ayant permis la mise en place des filons, est également discuté dans cet article.
{"title":"Minéralogie et métallogenèse des filons de barite plombifère de Wisembach (Fauvillers), Province de Luxembourg, Belgique","authors":"Michel Blondieau, Frédéric Hatert, Stéphane Puccio, Martin Depret, Fabrice Dal Bo","doi":"10.25518/0037-9565.11131","DOIUrl":"https://doi.org/10.25518/0037-9565.11131","url":null,"abstract":"Des filons plombifères à gangue baritée sont observés dans la région de Martelange et notamment à Wisembach dans la formation de Villé, une formation du Dévonien inférieur (Praguien) connue pour être traversée par de nombreux filons plombifères. La présence de barite dans ces filons est cependant atypique pour l’Ardenne belge, et cette observation semble indiquer une origine commune entre ces filons et ceux de la région de Vianden au Grand-duché de Luxembourg. La minéralogie des filons de Wisembach se résume à quelques espèces primaires et à des espèces supergènes, avec notamment la romanèchite, un oxyde de manganèse contenant du baryum dont la première occurrence belge est signalée ici. Le cadre structural, notamment les failles ayant permis la mise en place des filons, est également discuté dans cet article.","PeriodicalId":35838,"journal":{"name":"Bulletin de la Societe Royale des Sciences de Liege","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136373863","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.25518/0037-9565.11342
Mansour Aissaoui, Brahim Babali, Amel Sari Ali
The knowledge of the holoparasitic Orobanchaceae of Tlemcen region is updated through surveys based on eleven years of fieldwork, analysis and revision of bibliographic information and consultation of the main Herbaria related to the studied area. The detailed distribution in geographical units of the 20 taxa, belonging to the four genera: Boulardia, Cistanche, Orobanche and Phelipanche have been provided, together with habitat description and host plants. We also highlight the presence of taxa with marked chorological interest, rarely cited on the territory, such as O. alba, O. gracilis, O. hederae, P. portoilicitana and P. reuteriana. Note that the species: Cistanche violacea, Orobanche calendulae, Orobanche caryophyllacea, Orobanche reticulata, and Phelipanche cernuahave not been found in the Tlemcen area so far, so we will consider them as conflicting species to be searched.
通过11年的野外调查、文献资料的分析和修订以及与研究地区有关的主要植物标本馆的查阅，更新了对特莱姆森地区全寄生龙葵科植物的认识。本文详细地介绍了该植物所属的4属(Boulardia, Cistanche, orobche, Phelipanche) 20个分类群的地理单位分布，以及生境描述和寄主植物。我们还强调了在该地区很少被引用的具有明显的历史意义的分类群的存在，如O. alba, O. gracilis, O. hederae, P. portoilicitana和P. reuteriana。值得注意的是，到目前为止，在特莱姆森地区还没有发现紫肉苁梗、金盏肉苁梗、石竹肉苁梗、网纹肉苁梗和樱桃肉苁梗，因此我们将它们视为需要搜索的相互冲突的物种。
{"title":"The holoparasitic Orobanchaceae of Tlemcen region (north-western Algeria): diversity, distribution and host range","authors":"Mansour Aissaoui, Brahim Babali, Amel Sari Ali","doi":"10.25518/0037-9565.11342","DOIUrl":"https://doi.org/10.25518/0037-9565.11342","url":null,"abstract":"The knowledge of the holoparasitic Orobanchaceae of Tlemcen region is updated through surveys based on eleven years of fieldwork, analysis and revision of bibliographic information and consultation of the main Herbaria related to the studied area. The detailed distribution in geographical units of the 20 taxa, belonging to the four genera: Boulardia, Cistanche, Orobanche and Phelipanche have been provided, together with habitat description and host plants. We also highlight the presence of taxa with marked chorological interest, rarely cited on the territory, such as O. alba, O. gracilis, O. hederae, P. portoilicitana and P. reuteriana. Note that the species: Cistanche violacea, Orobanche calendulae, Orobanche caryophyllacea, Orobanche reticulata, and Phelipanche cernuahave not been found in the Tlemcen area so far, so we will consider them as conflicting species to be searched.","PeriodicalId":35838,"journal":{"name":"Bulletin de la Societe Royale des Sciences de Liege","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135053161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.25518/0037-9565.11197
Özgür Baştürk, Ekrem M. ESMER, Eylül DEMIR, Selim O. SELAM
Post-common Envelope Eclipsing Binary (PCEB) systems with a white or sub-dwarf primary and a low-mass secondary are ideal systems to study Eclipse Timing Variations (ETVs) due to their relatively small total masses which make it easy to detect gravitationally bound, yet unseen, additional bodies even within planetary limits on long-period orbits. With the addition of the recent discovery of two planetary-mass bodies in the sdB + dM binary Kepler-451 system, the number of circumbinary planets in PCEBs approaches 30 now. However, some of these systems turned out to be dynamically unstable with the suggested planetary parameters. As more observations accumulate over time, there have been significant changes in both the number of suggested planets and their parameters. These necessitate a look back to the ETV analyses of these systems with new and more precise data spanning longer baselines. Within this contribution, we review the systems hosting substellar bodies suggested from the light-time effect they are claimed to be causing. We list the general problems encountered during the ETV analyses and the interpretation of the results, and comment on their possible solutions. We cal-culate and present the potentials of supporting evidence from astrometry, radial velocity, and transit observations as well as tests through dynamical stability analyses and magnetic activity assumptions.
{"title":"Eclipse Timing Variations Observed in PCEB Systems","authors":"Özgür Baştürk, Ekrem M. ESMER, Eylül DEMIR, Selim O. SELAM","doi":"10.25518/0037-9565.11197","DOIUrl":"https://doi.org/10.25518/0037-9565.11197","url":null,"abstract":"Post-common Envelope Eclipsing Binary (PCEB) systems with a white or sub-dwarf primary and a low-mass secondary are ideal systems to study Eclipse Timing Variations (ETVs) due to their relatively small total masses which make it easy to detect gravitationally bound, yet unseen, additional bodies even within planetary limits on long-period orbits. With the addition of the recent discovery of two planetary-mass bodies in the sdB + dM binary Kepler-451 system, the number of circumbinary planets in PCEBs approaches 30 now. However, some of these systems turned out to be dynamically unstable with the suggested planetary parameters. As more observations accumulate over time, there have been significant changes in both the number of suggested planets and their parameters. These necessitate a look back to the ETV analyses of these systems with new and more precise data spanning longer baselines. Within this contribution, we review the systems hosting substellar bodies suggested from the light-time effect they are claimed to be causing. We list the general problems encountered during the ETV analyses and the interpretation of the results, and comment on their possible solutions. We cal-culate and present the potentials of supporting evidence from astrometry, radial velocity, and transit observations as well as tests through dynamical stability analyses and magnetic activity assumptions.","PeriodicalId":35838,"journal":{"name":"Bulletin de la Societe Royale des Sciences de Liege","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135053151","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.25518/0037-9565.11175
Ahmed Amine Tabet, Gihen Rym Abdaoui, Hafid Layeb
In this research work, the separation of built-up areas from bare lands in El Khroub city is carried out using a supervised classification approach involving several indices and combining spectral bands of the Sentinel-2A images sensor. The multi-index approach is based on the combination of seven indices in order to discriminate between the three main categories of land cover, which are water bodies, green areas and buildings. 3First, this operation requires the use of NDVI, BAEI, NDBI, NDTI, BUI, MNDWI and the NDVIre index, which have a strong discrimination capacity between build-up area and the other land cover features. The neo-images obtained from the combination of the above indices are then classified with the Likelihood algorithm for the extraction of the six class types of land cover (built-up areas, bare land, vegetation, forest, water bodies and asphalt). The multi-index obtained from the combination of BUI, NDTI and NDVIre is the most effective; shown by the evaluation values, where the Overall accuracy is of 96.44%, the Kappa Coefficient (K) of 95.72% and a User Accuracy for built-up class of the order of 100%, with a zero rate of commission. Therefore, the multi-index (BUI, NDTI and NDVIre) is retained for build-up area extraction due to its best discrimination capability.
{"title":"Automatic extraction of build-up areas from bare land using Sentinel 2A imagery in El Khroub city, Algeria","authors":"Ahmed Amine Tabet, Gihen Rym Abdaoui, Hafid Layeb","doi":"10.25518/0037-9565.11175","DOIUrl":"https://doi.org/10.25518/0037-9565.11175","url":null,"abstract":"In this research work, the separation of built-up areas from bare lands in El Khroub city is carried out using a supervised classification approach involving several indices and combining spectral bands of the Sentinel-2A images sensor. The multi-index approach is based on the combination of seven indices in order to discriminate between the three main categories of land cover, which are water bodies, green areas and buildings. 3First, this operation requires the use of NDVI, BAEI, NDBI, NDTI, BUI, MNDWI and the NDVIre index, which have a strong discrimination capacity between build-up area and the other land cover features. The neo-images obtained from the combination of the above indices are then classified with the Likelihood algorithm for the extraction of the six class types of land cover (built-up areas, bare land, vegetation, forest, water bodies and asphalt). The multi-index obtained from the combination of BUI, NDTI and NDVIre is the most effective; shown by the evaluation values, where the Overall accuracy is of 96.44%, the Kappa Coefficient (K) of 95.72% and a User Accuracy for built-up class of the order of 100%, with a zero rate of commission. Therefore, the multi-index (BUI, NDTI and NDVIre) is retained for build-up area extraction due to its best discrimination capability.","PeriodicalId":35838,"journal":{"name":"Bulletin de la Societe Royale des Sciences de Liege","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135053155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.25518/0037-9565.11209
C. Simon Jeffery, Itumeleng Monageng, Brent Miszalski, Edward J. Snowdon, Laura J.A. Scott, Vincent M. Woolf, Matti Dorsh
The Southern African Large Telescope (SALT) has surveyed a sample of 300 chemically-peculiar hot subdwarfs with a view to explore evolutionary pathways and connections between a large variety of stars. Observations have been obtained for the entire sample at intermediate resolution to provide classifications and atmosphere parameters, and a smaller sample at high resolution to permit detailed chemical abundance analyses. The first has provided a substantial sample of extremely helium-rich sdO stars, but has also led to significant discoveries of hot white dwarfs, pre-white dwarfs, heavy-metal subdwarfs and extreme helium stars. This paper provides an overview of the current status of the project.
{"title":"The SALT survey of chemically-peculiar hot subdwarfs","authors":"C. Simon Jeffery, Itumeleng Monageng, Brent Miszalski, Edward J. Snowdon, Laura J.A. Scott, Vincent M. Woolf, Matti Dorsh","doi":"10.25518/0037-9565.11209","DOIUrl":"https://doi.org/10.25518/0037-9565.11209","url":null,"abstract":"The Southern African Large Telescope (SALT) has surveyed a sample of 300 chemically-peculiar hot subdwarfs with a view to explore evolutionary pathways and connections between a large variety of stars. Observations have been obtained for the entire sample at intermediate resolution to provide classifications and atmosphere parameters, and a smaller sample at high resolution to permit detailed chemical abundance analyses. The first has provided a substantial sample of extremely helium-rich sdO stars, but has also led to significant discoveries of hot white dwarfs, pre-white dwarfs, heavy-metal subdwarfs and extreme helium stars. This paper provides an overview of the current status of the project.","PeriodicalId":35838,"journal":{"name":"Bulletin de la Societe Royale des Sciences de Liege","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135053480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.25518/0037-9565.11266
M. D. REED, A. S. BARAN, R. H. ØSTENSEN, J. H. TELTING, C. S. JEFFERY
The original Kepler mission detected 18 pulsating subdwarf B (sdBV) stars, K2 observed 161 of our proposed targets with 41 sdB stars found to show p- or g-mode pulsations, and TESS has observed about 1,000 of our proposed targets. All these data should provide ∼300 sdBV stars, from which asteroseismology will provide a host of measurables. Combined with temperatures and gravities (and radii and masses from GAIA parallaxes!), we have a powerful set of observations with which to compare models. Here we review our seismology progress with sdBV stars.
{"title":"Kepler, K2, and TESS observations: ensemble and comparative asteroseismology","authors":"M. D. REED, A. S. BARAN, R. H. ØSTENSEN, J. H. TELTING, C. S. JEFFERY","doi":"10.25518/0037-9565.11266","DOIUrl":"https://doi.org/10.25518/0037-9565.11266","url":null,"abstract":"The original Kepler mission detected 18 pulsating subdwarf B (sdBV) stars, K2 observed 161 of our proposed targets with 41 sdB stars found to show p- or g-mode pulsations, and TESS has observed about 1,000 of our proposed targets. All these data should provide ∼300 sdBV stars, from which asteroseismology will provide a host of measurables. Combined with temperatures and gravities (and radii and masses from GAIA parallaxes!), we have a powerful set of observations with which to compare models. Here we review our seismology progress with sdBV stars.","PeriodicalId":35838,"journal":{"name":"Bulletin de la Societe Royale des Sciences de Liege","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135051982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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