Spectral classification & physical parameters of the IPHAS CBe stars in the BCD system.
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Spectral classification & physical parameters of the IPHAS CBe stars in the BCD system.

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Spectral classification & physical parameters of the IPHAS CBe stars in the BCD system.

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dc.contributor.advisor Fabregat Llueca, Juan
dc.contributor.author Gkouvelis, Leonardos
dc.contributor.other Departament d'Astronomia i Astrofísica es_ES
dc.date.accessioned 2017-06-21T09:48:07Z
dc.date.available 2017-06-22T04:45:06Z
dc.date.issued 2017 es_ES
dc.date.submitted 29-05-2017 es_ES
dc.identifier.uri http://hdl.handle.net/10550/59153
dc.description.abstract The INT Photometric Hα Survey (IPHAS) has detected tens of thousands of emission line objects in the Northern Galactic Plane. Spectroscopic follow-up has shown that the vast majority of them are Classical Be (CBe) stars, rapidly rotat- ing main sequence B type stars which develop an outflowing circumstellar disk by mechanisms not yet completely understood. In this work we present a study of the full catalogue of the CBe stars discovered by IPHAS. We have analyzed 805 low resolution spectra of 732 IPHAS CBe stars. With a semi-automatic proce- dure, which we evaluate at the first part of this work, we obtained the relevant physical parameters, including the effective temperature, surface gravity, absolute magnitude and distance, based on the techniques of the Barbier-Chalonge-Divan (BCD) spectrophotometric system. Also, we plot an HR diagram from which we extracted masses and ages. From the data in the catalogue we have determined for the sample a mean rotational velocity of 82% of the critical velocity, without any trend of variation with the spectral type. The data also confirm that the circumstellar discs rotate following a Keplerian velocity law. We found the ages of the stars evenly distributed be- tween the ZAMS and the TAMS, and hence our results do not support claims of an evolutionary nature of the Be phenomenon. The distribution of the stars does not present an apparent clustering in or around the Perseus or the Outer Arm regions. Instead, they appear scattered along the two arms and the space in between, with some stars spreaded along larger dis- tances, beyond the expected location of the Outer Arm. The density of the stars beyond the Perseus Arm displays a similar exponential decline at all longitudes along the Northern Galactic Plane. No evidence of an outer Arm beyond the Perseus Arm is present in our data. es_ES
dc.format.extent 169 p. es_ES
dc.language.iso en es_ES
dc.subject Be stars, rotationa velocities, circumstellar disc, galactic structure es_ES
dc.title Spectral classification & physical parameters of the IPHAS CBe stars in the BCD system. es_ES
dc.type info:eu-repo/semantics/doctoralThesis es_ES
dc.subject.unesco UNESCO::ASTRONOMÍA Y ASTROFÍSICA es_ES
dc.description.abstractenglish The INT Photometric Hα Survey (IPHAS) has detected tens of thousands of emission line objects in the Northern Galactic Plane. Spectroscopic follow-up has shown that the vast majority of them are Classical Be (CBe) stars, rapidly rotat- ing main sequence B type stars which develop an outflowing circumstellar disk by mechanisms not yet completely understood. In this work we present a study of the full catalogue of the CBe stars discovered by IPHAS. We have analyzed 805 low resolution spectra of 732 IPHAS CBe stars. With a semi-automatic proce- dure, which we evaluate at the first part of this work, we obtained the relevant physical parameters, including the effective temperature, surface gravity, absolute magnitude and distance, based on the techniques of the Barbier-Chalonge-Divan (BCD) spectrophotometric system. Also, we plot an HR diagram from which we extracted masses and ages. From the data in the catalogue we have determined for the sample a mean rotational velocity of 82% of the critical velocity, without any trend of variation with the spectral type. The data also confirm that the circumstellar discs rotate following a Keplerian velocity law. We found the ages of the stars evenly distributed be- tween the ZAMS and the TAMS, and hence our results do not support claims of an evolutionary nature of the Be phenomenon. The distribution of the stars does not present an apparent clustering in or around the Perseus or the Outer Arm regions. Instead, they appear scattered along the two arms and the space in between, with some stars spreaded along larger dis- tances, beyond the expected location of the Outer Arm. The density of the stars beyond the Perseus Arm displays a similar exponential decline at all longitudes along the Northern Galactic Plane. No evidence of an outer Arm beyond the Perseus Arm is present in our data. es_ES
dc.embargo.terms 0 days es_ES

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