{"id":{"repo_id":"the-open-u","oai_identifier":"oai:oro.open.ac.uk:53764"},"canonical_url":"https://search.dev.ndltd.org/etd/the-open-u/oai:oro.open.ac.uk:53764","repository":{"repo_id":"the-open-u","name":"The Open University","base_url":"https://oro.open.ac.uk/cgi/oai2"},"display":{"title":"Enshrouded Exoplanetary Systems","abstract":"This thesis is based on the hypothesis that stars hosting short period planets can show anomalously low apparent stellar activity values caused by planetary mass-loss enshrouding the system. The resulting circumstellar absorption depresses the cores of the Ca II H&K lines, where the activity index log(R'<sub>HK</sub>) is measured. I searched for this effect in a sample of ∼2700 stars, identifying 39 objects with log(R'<sub>HK</sub>) below the main sequence basal limit, and 6 Hyades and Pleiades stars with activity levels well below the cluster distributions. I describe a radial velocity programme to search for short period planets orbiting these stars. Because nearby bright stars are targeted, their mass-losing companions will offer key opportunities to probe planetary composition through transmission spectroscopy. I present four planet candidates discovered through this programme orbiting HD11231 and HD38677. The former is a γ-Doradus pulsator hosting a Saturn-mass planet in a 6 day orbit, and the latter is a compact system containing planets with ∼18, 13 and 3 Earth masses and periods between 20 and 1.7 days. <br></br><br></br> In addition, the Robert Stobie Spectrograph was calibrated to measure log(R'<sub>HK</sub>) values. The activity index of the known Hot Jupiter hosts WASP-43, WASP-51/HAT-P-30, WASP-72 & WASP-103 was measured to search for anomalous values caused by the companions. The activity level of WASP-43 is extremely high in absolute terms and relative to its age and X-ray emission. The activity of WASP-103 is marginally higher than expected from the system age. In both cases, star-planet interactions may enhance Ca II H & K emission. WASP-51/HAT-P-30 and WASP-72 show anomalously low activity; the latter falls below the basal envelopes of main sequence and evolved stars. I highlight that a quarter of transiting, short period planets hosts with published activity data exhibit anomalously low activity. These 22 systems include Hot Jupiters and low mass companions.","abstract_html":"This thesis is based on the hypothesis that stars hosting short period planets can show anomalously low apparent stellar activity values caused by planetary mass-loss enshrouding the system. The resulting circumstellar absorption depresses the cores of the Ca II H&amp;K lines, where the activity index log(R&#x27;&lt;sub&gt;HK&lt;/sub&gt;) is measured. I searched for this effect in a sample of ∼2700 stars, identifying 39 objects with log(R&#x27;&lt;sub&gt;HK&lt;/sub&gt;) below the main sequence basal limit, and 6 Hyades and Pleiades stars with activity levels well below the cluster distributions. I describe a radial velocity programme to search for short period planets orbiting these stars. Because nearby bright stars are targeted, their mass-losing companions will offer key opportunities to probe planetary composition through transmission spectroscopy. I present four planet candidates discovered through this programme orbiting HD11231 and HD38677. The former is a γ-Doradus pulsator hosting a Saturn-mass planet in a 6 day orbit, and the latter is a compact system containing planets with ∼18, 13 and 3 Earth masses and periods between 20 and 1.7 days. &lt;br&gt;&lt;/br&gt;&lt;br&gt;&lt;/br&gt; In addition, the Robert Stobie Spectrograph was calibrated to measure log(R&#x27;&lt;sub&gt;HK&lt;/sub&gt;) values. The activity index of the known Hot Jupiter hosts WASP-43, WASP-51/HAT-P-30, WASP-72 &amp; WASP-103 was measured to search for anomalous values caused by the companions. The activity level of WASP-43 is extremely high in absolute terms and relative to its age and X-ray emission. The activity of WASP-103 is marginally higher than expected from the system age. In both cases, star-planet interactions may enhance Ca II H &amp; K emission. WASP-51/HAT-P-30 and WASP-72 show anomalously low activity; the latter falls below the basal envelopes of main sequence and evolved stars. I highlight that a quarter of transiting, short period planets hosts with published activity data exhibit anomalously low activity. These 22 systems include Hot Jupiters and low mass companions.","abstract_has_math":false,"creators":["Staab, Daniel"],"institution":"The Open University","degree_name":"phd","degree_level":"doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2018,"date_issued":"2018-03","date_published":"2018-03","updated_at":"2026-07-24T05:02:39Z","subjects":[],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":null,"outbound_label":null,"outbound_source":null},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Staab, Daniel"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2018-03-08"]},{"key":"dc:date.issued","label":"Date","values":["2018-03"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["ARRAY(0x7ffb7438efb0)"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["The Open University"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["https://oro.open.ac.uk/53764/"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["doctoral"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["phd"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://oro.open.ac.uk/53764/1/DanielStaab_thesis.pdf","https://oro.open.ac.uk/53764/17/Library%20Deposition%20Memo.doc","https://oro.open.ac.uk/53764/18/Thesis%20Deposition%20Form.pdf","https://oro.open.ac.uk/53764/19/GRADPROG%20Memo.doc"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["This thesis is based on the hypothesis that stars hosting short period planets can show anomalously low apparent stellar activity values caused by planetary mass-loss enshrouding the system. The resulting circumstellar absorption depresses the cores of the Ca II H&K lines, where the activity index log(R'<sub>HK</sub>) is measured. I searched for this effect in a sample of ∼2700 stars, identifying 39 objects with log(R'<sub>HK</sub>) below the main sequence basal limit, and 6 Hyades and Pleiades stars with activity levels well below the cluster distributions. I describe a radial velocity programme to search for short period planets orbiting these stars. Because nearby bright stars are targeted, their mass-losing companions will offer key opportunities to probe planetary composition through transmission spectroscopy. I present four planet candidates discovered through this programme orbiting HD11231 and HD38677. The former is a γ-Doradus pulsator hosting a Saturn-mass planet in a 6 day orbit, and the latter is a compact system containing planets with ∼18, 13 and 3 Earth masses and periods between 20 and 1.7 days. <br></br><br></br> In addition, the Robert Stobie Spectrograph was calibrated to measure log(R'<sub>HK</sub>) values. The activity index of the known Hot Jupiter hosts WASP-43, WASP-51/HAT-P-30, WASP-72 & WASP-103 was measured to search for anomalous values caused by the companions. The activity level of WASP-43 is extremely high in absolute terms and relative to its age and X-ray emission. The activity of WASP-103 is marginally higher than expected from the system age. In both cases, star-planet interactions may enhance Ca II H & K emission. WASP-51/HAT-P-30 and WASP-72 show anomalously low activity; the latter falls below the basal envelopes of main sequence and evolved stars. I highlight that a quarter of transiting, short period planets hosts with published activity data exhibit anomalously low activity. These 22 systems include Hot Jupiters and low mass companions."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf","application/msword"]},{"key":"dc:title","label":"Title","values":["Enshrouded Exoplanetary Systems"]}]}],"canonical_facts":{"dc:creator":["Staab, Daniel"],"dc:date":["2018-03-08"],"dc:date.issued":["2018-03"],"dc:description.abstract":["This thesis is based on the hypothesis that stars hosting short period planets can show anomalously low apparent stellar activity values caused by planetary mass-loss enshrouding the system. The resulting circumstellar absorption depresses the cores of the Ca II H&K lines, where the activity index log(R'<sub>HK</sub>) is measured. I searched for this effect in a sample of ∼2700 stars, identifying 39 objects with log(R'<sub>HK</sub>) below the main sequence basal limit, and 6 Hyades and Pleiades stars with activity levels well below the cluster distributions. I describe a radial velocity programme to search for short period planets orbiting these stars. Because nearby bright stars are targeted, their mass-losing companions will offer key opportunities to probe planetary composition through transmission spectroscopy. I present four planet candidates discovered through this programme orbiting HD11231 and HD38677. The former is a γ-Doradus pulsator hosting a Saturn-mass planet in a 6 day orbit, and the latter is a compact system containing planets with ∼18, 13 and 3 Earth masses and periods between 20 and 1.7 days. <br></br><br></br> In addition, the Robert Stobie Spectrograph was calibrated to measure log(R'<sub>HK</sub>) values. The activity index of the known Hot Jupiter hosts WASP-43, WASP-51/HAT-P-30, WASP-72 & WASP-103 was measured to search for anomalous values caused by the companions. The activity level of WASP-43 is extremely high in absolute terms and relative to its age and X-ray emission. The activity of WASP-103 is marginally higher than expected from the system age. In both cases, star-planet interactions may enhance Ca II H & K emission. WASP-51/HAT-P-30 and WASP-72 show anomalously low activity; the latter falls below the basal envelopes of main sequence and evolved stars. I highlight that a quarter of transiting, short period planets hosts with published activity data exhibit anomalously low activity. These 22 systems include Hot Jupiters and low mass companions."],"dc:format":["application/pdf","application/msword"],"dc:identifier.uri":["https://oro.open.ac.uk/53764/1/DanielStaab_thesis.pdf","https://oro.open.ac.uk/53764/17/Library%20Deposition%20Memo.doc","https://oro.open.ac.uk/53764/18/Thesis%20Deposition%20Form.pdf","https://oro.open.ac.uk/53764/19/GRADPROG%20Memo.doc"],"dc:language":["en"],"dc:publisher.department":["ARRAY(0x7ffb7438efb0)"],"dc:publisher.institution":["The Open University"],"dc:relation.isreferencedby":["https://oro.open.ac.uk/53764/"],"dc:title":["Enshrouded Exoplanetary Systems"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["doctoral"],"dc:type.qualificationname":["phd"]},"updated_at":"2026-07-24T05:02:39Z"}