{"id":{"repo_id":"catania","oai_identifier":"oai:www.iris.unict.it:20.500.11769/587323"},"canonical_url":"https://search.dev.ndltd.org/etd/catania/oai:www.iris.unict.it:20.500.11769/587323","repository":{"repo_id":"catania","name":"Università degli Studi di Catania","base_url":"https://www.iris.unict.it/oai/request"},"display":{"title":"Effects of starspots activity on optical and near infrared observations of planetary transits","abstract":"In this thesis, I report on the effects that magnetic stellar activity of solar-type stars induces on stellar light curves involved in the photometric technique for the detection and characterization of transiting extra-solar planets that is one of the most effective detection methods, the first being the radial velocity technique. Stellar magnetic activity is a source of noise in the study of the transits of extra-solar planets since it induces flux variations that significantly affect the transit depth determination and the derivations of planetary and stellar parameters. Surface brightness inhomogeneities, such as starspots or bright faculae, on star disc have an intrinsic dependence on wavelength and thus on the stellar colours. The colour dependence of stellar activity may significantly influence the characterization of planetary atmospheres since it produces stellar flux variations that may mimic those due to the presence of molecular or atomic species in the transmitted planetary spectra. In this thesis I focus on the effects due essentially to stellar spots present in the visible hemisphere of solar-type stars. The proposed method is a theoretical one, aiming to predict the starspot-induced effects with the use of stellar atmospheric models and I present a systematic approach to quantify the corresponding stellar flux variations as a function of wavelength bands. Therefore I consider a star with spots covering a given fraction of its disc and model the variability in both the UBVRIJHK photometric system and the Spitzer/IRAC wavebands for dwarf stars from G to M spectral types. Then I compare starspot-induced flux variations in these different passbands with planetary transits and quantify how they affect the determination of the planetary radius and the analysis of the transmission spectroscopy in the study of planetary atmospheres. My results suggest that the monitoring of the systems by using broad-band photometry, from visible to infrared, helps to constrain spots effects by estimating the R parameter, i.e. the ratio of the relative variations in the stellar fluxes at short wavelength optical bands (e.g., U or B) to near-infrared ones (e.g., J or K). Its numerical value can be used to distinguish starspot brightness dips from planetary transits in a single stellar light curve. In addition to the perturbations in the measurement of the planetary radius, the perturbations in the transit light curve profiles due to starspots can affect the determinations of orbital parameters, i.e., the relative semi-major axis and the inclination of the planetary orbit, that are directly derived by fitting procedure of the transit light curves. These distortions in the transit light curves have a significant impact on the derivation of stellar parameters and, above all, on the stellar density thus bothering the stellar evolutionary estimates. The results derived from the synthetic photometric analysis are presented and discussed in Ballerini et al. 2012.","abstract_html":"In this thesis, I report on the effects that magnetic stellar activity of solar-type stars induces on stellar light curves involved in the photometric technique for the detection and characterization of transiting extra-solar planets that is one of the most effective detection methods, the first being the radial velocity technique. Stellar magnetic activity is a source of noise in the study of the transits of extra-solar planets since it induces flux variations that significantly affect the transit depth determination and the derivations of planetary and stellar parameters. Surface brightness inhomogeneities, such as starspots or bright faculae, on star disc have an intrinsic dependence on wavelength and thus on the stellar colours. The colour dependence of stellar activity may significantly influence the characterization of planetary atmospheres since it produces stellar flux variations that may mimic those due to the presence of molecular or atomic species in the transmitted planetary spectra. In this thesis I focus on the effects due essentially to stellar spots present in the visible hemisphere of solar-type stars. The proposed method is a theoretical one, aiming to predict the starspot-induced effects with the use of stellar atmospheric models and I present a systematic approach to quantify the corresponding stellar flux variations as a function of wavelength bands. Therefore I consider a star with spots covering a given fraction of its disc and model the variability in both the UBVRIJHK photometric system and the Spitzer/IRAC wavebands for dwarf stars from G to M spectral types. Then I compare starspot-induced flux variations in these different passbands with planetary transits and quantify how they affect the determination of the planetary radius and the analysis of the transmission spectroscopy in the study of planetary atmospheres. My results suggest that the monitoring of the systems by using broad-band photometry, from visible to infrared, helps to constrain spots effects by estimating the R parameter, i.e. the ratio of the relative variations in the stellar fluxes at short wavelength optical bands (e.g., U or B) to near-infrared ones (e.g., J or K). Its numerical value can be used to distinguish starspot brightness dips from planetary transits in a single stellar light curve. In addition to the perturbations in the measurement of the planetary radius, the perturbations in the transit light curve profiles due to starspots can affect the determinations of orbital parameters, i.e., the relative semi-major axis and the inclination of the planetary orbit, that are directly derived by fitting procedure of the transit light curves. These distortions in the transit light curves have a significant impact on the derivation of stellar parameters and, above all, on the stellar density thus bothering the stellar evolutionary estimates. The results derived from the synthetic photometric analysis are presented and discussed in Ballerini et al. 2012.","abstract_has_math":false,"creators":["BALLERINI, PAOLA"],"institution":"Università degli studi di Catania","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["LANZAFAME, Alessandro Carmelo","RIGGI, Francesco"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2012,"date_issued":"2012-12-10","date_published":"2012-12-10","updated_at":"2026-07-24T01:35:17Z","subjects":["stars, photometry, activity, starspot"],"languages":["eng"],"rights":["info:eu-repo/semantics/openAccess","license:PUBBLICO - Pubblico con Copyright","license uri:iris.PUB02"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/20.500.11769/587323","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Ballerini, Paola","LANZAFAME, Alessandro Carmelo","RIGGI, Francesco"]},{"key":"dc:creator","label":"Author","values":["BALLERINI, PAOLA"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2012-12-10"]},{"key":"dc:publisher","label":"Institution","values":["Università degli studi di Catania","place:Catania"]},{"key":"dc:type","label":"Dc Type","values":["info:eu-repo/semantics/doctoralThesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["stars, photometry, activity, starspot"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["info:eu-repo/semantics/openAccess","license:PUBBLICO - Pubblico con Copyright","license uri:iris.PUB02"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/20.500.11769/587323"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["In this thesis, I report on the effects that magnetic stellar activity of solar-type stars induces on stellar light curves involved in the photometric technique for the detection and characterization of transiting extra-solar planets that is one of the most effective detection methods, the first being the radial velocity technique. Stellar magnetic activity is a source of noise in the study of the transits of extra-solar planets since it induces flux variations that significantly affect the transit depth determination and the derivations of planetary and stellar parameters. Surface brightness inhomogeneities, such as starspots or bright faculae, on star disc have an intrinsic dependence on wavelength and thus on the stellar colours. The colour dependence of stellar activity may significantly influence the characterization of planetary atmospheres since it produces stellar flux variations that may mimic those due to the presence of molecular or atomic species in the transmitted planetary spectra. In this thesis I focus on the effects due essentially to stellar spots present in the visible hemisphere of solar-type stars. The proposed method is a theoretical one, aiming to predict the starspot-induced effects with the use of stellar atmospheric models and I present a systematic approach to quantify the corresponding stellar flux variations as a function of wavelength bands. Therefore I consider a star with spots covering a given fraction of its disc and model the variability in both the UBVRIJHK photometric system and the Spitzer/IRAC wavebands for dwarf stars from G to M spectral types. Then I compare starspot-induced flux variations in these different passbands with planetary transits and quantify how they affect the determination of the planetary radius and the analysis of the transmission spectroscopy in the study of planetary atmospheres. My results suggest that the monitoring of the systems by using broad-band photometry, from visible to infrared, helps to constrain spots effects by estimating the R parameter, i.e. the ratio of the relative variations in the stellar fluxes at short wavelength optical bands (e.g., U or B) to near-infrared ones (e.g., J or K). Its numerical value can be used to distinguish starspot brightness dips from planetary transits in a single stellar light curve. In addition to the perturbations in the measurement of the planetary radius, the perturbations in the transit light curve profiles due to starspots can affect the determinations of orbital parameters, i.e., the relative semi-major axis and the inclination of the planetary orbit, that are directly derived by fitting procedure of the transit light curves. These distortions in the transit light curves have a significant impact on the derivation of stellar parameters and, above all, on the stellar density thus bothering the stellar evolutionary estimates. The results derived from the synthetic photometric analysis are presented and discussed in Ballerini et al. 2012.","In questa tesi, presento una relazione sugli effetti che l'attività magnetica stellare di stelle di tipo solare induce su curve di luce stellari utilizzate nella tecnica fotometrica per la rilevazione e la caratterizzazione dei pianeti extra-solari transitanti che è uno dei metodi di rilevazione più efficaci, il primo è la tecnica delle velocità radiali. L'attività magnetica stellare è una sorgente di rumore nello studio dei transiti di pianeti extrasolari poiché induce variazioni di flusso che influenzano in modo significativo la determinazione della profondità del transito e le derivazioni di parametri planetari e stellari. Le disomogeneità superficiali della luminosità, come le macchie stellari o le brillanti faculae, sul disco stellare hanno una dipendenza intrinseca dalla lunghezza d'onda e quindi dai colori stellari. La dipendenza dell'attività stellare dal colore può influenzare significativamente la caratterizzazione delle atmosfere planetarie in quanto produce variazioni di flusso stellare che possono riprodurre quelle dovute alla presenza di specie molecolari o atomiche negli spettri planetari trasmessi. In questa tesi mi sono concentrata sugli effetti dovuti essenzialmente a macchie stellari presenti nell'emisfero visibile delle stelle di tipo solare. Il metodo proposto è di tipo teorico al fine di prevedere gli effetti indotti dalle macchie stellari con l'uso di modelli stellari atmosferici e io presento un approccio sistematico per quantificare le corrispondenti variazioni di flusso stellare in funzione della lunghezza d'onda. Considero quindi una stella con macchia che coprono una data frazione del suo disco e modello la variabilità considerando il sistema fotometrico UBVRIJHK e le bande di lunghezza d'onda di Spitzer / IRAC per stelle nane da tipo spettrale G a quello M. Poi confronto le variazioni di flusso indotte dalla macchie stellari in queste bande passanti differenti con i transiti planetari e quantifico come le macchie stellari influenzino la determinazione del raggio planetario e l'analisi della spettro stellare in trasmissione nello studio delle atmosfere planetarie. I miei risultati suggeriscono che monitorare i sistemi stellari utilizzando una larga banda fotometrica, da visibile a infrarossi, aiuta a limitare gli effetti delle macchie stimando il parametro R, cioè il rapporto tra le variazioni relative di flussi stellari in bande ottiche di piccola lunghezza d'onda (ad esempio, U o B) e quelle nel vicino infrarosso (ad esempio, J o K). Il suo valore numerico può essere utilizzato per distinguere riduzioni di luminosità dovute a macchie stellari dai transiti planetari osservando una sola curva di luce stellare. Oltre alle perturbazioni nella misura del raggio planetario, le perturbazioni nei profili delle curve di luce dei transiti causati da macchie stellari possono influenzare le determinazioni di parametri orbitali, cioè, il semi-asse maggiore relativo e l'inclinazione dell'orbita planetaria, che sono direttamente derivate da procedura di best-fit della curve di luce del transito. Queste distorsioni nelle curve di luce di un transito hanno un impatto significativo sulla derivazione di parametri stellari e, soprattutto, sulla densità stellare così compromettendo le stime evolutive stellari. I risultati ottenuti dall'analisi fotometrica sintetica sono presentati e discussi in Ballerini et al. 2012."]},{"key":"dc:title","label":"Title","values":["Effects of starspots activity on optical and near infrared observations of planetary transits"]}]}],"canonical_facts":{"dc:contributor":["Ballerini, Paola","LANZAFAME, Alessandro Carmelo","RIGGI, Francesco"],"dc:creator":["BALLERINI, PAOLA"],"dc:date":["2012-12-10"],"dc:description":["In this thesis, I report on the effects that magnetic stellar activity of solar-type stars induces on stellar light curves involved in the photometric technique for the detection and characterization of transiting extra-solar planets that is one of the most effective detection methods, the first being the radial velocity technique. Stellar magnetic activity is a source of noise in the study of the transits of extra-solar planets since it induces flux variations that significantly affect the transit depth determination and the derivations of planetary and stellar parameters. Surface brightness inhomogeneities, such as starspots or bright faculae, on star disc have an intrinsic dependence on wavelength and thus on the stellar colours. The colour dependence of stellar activity may significantly influence the characterization of planetary atmospheres since it produces stellar flux variations that may mimic those due to the presence of molecular or atomic species in the transmitted planetary spectra. In this thesis I focus on the effects due essentially to stellar spots present in the visible hemisphere of solar-type stars. The proposed method is a theoretical one, aiming to predict the starspot-induced effects with the use of stellar atmospheric models and I present a systematic approach to quantify the corresponding stellar flux variations as a function of wavelength bands. Therefore I consider a star with spots covering a given fraction of its disc and model the variability in both the UBVRIJHK photometric system and the Spitzer/IRAC wavebands for dwarf stars from G to M spectral types. Then I compare starspot-induced flux variations in these different passbands with planetary transits and quantify how they affect the determination of the planetary radius and the analysis of the transmission spectroscopy in the study of planetary atmospheres. My results suggest that the monitoring of the systems by using broad-band photometry, from visible to infrared, helps to constrain spots effects by estimating the R parameter, i.e. the ratio of the relative variations in the stellar fluxes at short wavelength optical bands (e.g., U or B) to near-infrared ones (e.g., J or K). Its numerical value can be used to distinguish starspot brightness dips from planetary transits in a single stellar light curve. In addition to the perturbations in the measurement of the planetary radius, the perturbations in the transit light curve profiles due to starspots can affect the determinations of orbital parameters, i.e., the relative semi-major axis and the inclination of the planetary orbit, that are directly derived by fitting procedure of the transit light curves. These distortions in the transit light curves have a significant impact on the derivation of stellar parameters and, above all, on the stellar density thus bothering the stellar evolutionary estimates. The results derived from the synthetic photometric analysis are presented and discussed in Ballerini et al. 2012.","In questa tesi, presento una relazione sugli effetti che l'attività magnetica stellare di stelle di tipo solare induce su curve di luce stellari utilizzate nella tecnica fotometrica per la rilevazione e la caratterizzazione dei pianeti extra-solari transitanti che è uno dei metodi di rilevazione più efficaci, il primo è la tecnica delle velocità radiali. L'attività magnetica stellare è una sorgente di rumore nello studio dei transiti di pianeti extrasolari poiché induce variazioni di flusso che influenzano in modo significativo la determinazione della profondità del transito e le derivazioni di parametri planetari e stellari. Le disomogeneità superficiali della luminosità, come le macchie stellari o le brillanti faculae, sul disco stellare hanno una dipendenza intrinseca dalla lunghezza d'onda e quindi dai colori stellari. La dipendenza dell'attività stellare dal colore può influenzare significativamente la caratterizzazione delle atmosfere planetarie in quanto produce variazioni di flusso stellare che possono riprodurre quelle dovute alla presenza di specie molecolari o atomiche negli spettri planetari trasmessi. In questa tesi mi sono concentrata sugli effetti dovuti essenzialmente a macchie stellari presenti nell'emisfero visibile delle stelle di tipo solare. Il metodo proposto è di tipo teorico al fine di prevedere gli effetti indotti dalle macchie stellari con l'uso di modelli stellari atmosferici e io presento un approccio sistematico per quantificare le corrispondenti variazioni di flusso stellare in funzione della lunghezza d'onda. Considero quindi una stella con macchia che coprono una data frazione del suo disco e modello la variabilità considerando il sistema fotometrico UBVRIJHK e le bande di lunghezza d'onda di Spitzer / IRAC per stelle nane da tipo spettrale G a quello M. Poi confronto le variazioni di flusso indotte dalla macchie stellari in queste bande passanti differenti con i transiti planetari e quantifico come le macchie stellari influenzino la determinazione del raggio planetario e l'analisi della spettro stellare in trasmissione nello studio delle atmosfere planetarie. I miei risultati suggeriscono che monitorare i sistemi stellari utilizzando una larga banda fotometrica, da visibile a infrarossi, aiuta a limitare gli effetti delle macchie stimando il parametro R, cioè il rapporto tra le variazioni relative di flussi stellari in bande ottiche di piccola lunghezza d'onda (ad esempio, U o B) e quelle nel vicino infrarosso (ad esempio, J o K). Il suo valore numerico può essere utilizzato per distinguere riduzioni di luminosità dovute a macchie stellari dai transiti planetari osservando una sola curva di luce stellare. Oltre alle perturbazioni nella misura del raggio planetario, le perturbazioni nei profili delle curve di luce dei transiti causati da macchie stellari possono influenzare le determinazioni di parametri orbitali, cioè, il semi-asse maggiore relativo e l'inclinazione dell'orbita planetaria, che sono direttamente derivate da procedura di best-fit della curve di luce del transito. Queste distorsioni nelle curve di luce di un transito hanno un impatto significativo sulla derivazione di parametri stellari e, soprattutto, sulla densità stellare così compromettendo le stime evolutive stellari. I risultati ottenuti dall'analisi fotometrica sintetica sono presentati e discussi in Ballerini et al. 2012."],"dc:identifier":["https://hdl.handle.net/20.500.11769/587323"],"dc:language":["eng"],"dc:publisher":["Università degli studi di Catania","place:Catania"],"dc:rights":["info:eu-repo/semantics/openAccess","license:PUBBLICO - Pubblico con Copyright","license uri:iris.PUB02"],"dc:subject":["stars, photometry, activity, starspot"],"dc:title":["Effects of starspots activity on optical and near infrared observations of planetary transits"],"dc:type":["info:eu-repo/semantics/doctoralThesis"]},"updated_at":"2026-07-24T01:35:17Z"}