The changing UV and X-ray properties of the Of?p star CPD −28°2561

Nazé, Yaël; Sundqvist, J. O.; Fullerton, A. W.; ud‐Doula, Asif; Wade, G. A.; Rauw, Grégor; Walborn, N. R.

doi:10.1093/mnras/stv1445

Cited by 22 publications

(38 citation statements)

References 54 publications

(113 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The effective temperature of this object reaches ∼ 40000 K, its gravity log g ∼ 4.0, and its mass approximately 50-60 M (Nazé et al 2008a;Martins et al 2015). It displays chemical enrichment, but with a level comparable to O supergiants (Martins et al 2015).…”

Section: Introductionmentioning

confidence: 94%

“…Their measurements were, in general, in good agreement. Before comparing the RVs of these different parts, it is worth noting that the velocity of the center-of-mass of HD 148937 was measured to be −26 km s −1 (Nazé et al 2008a). A part of the NW lobe (constituting NGC 6164) is moving away from the observer with RVs between +21 and +55 km s −1 but another part of this region is also approaching the observer with a RV of −3 km s −1 .…”

Section: Kinematics Of the Nebulamentioning

confidence: 99%

See 1 more Smart Citation

Evolutionary status of the Of?p star HD 148937 and of its surrounding nebula NGC 6164/5

Mahy

Hutsemékers

Nazé

et al. 2017

A&A

View full text Add to dashboard Cite

Aims. The magnetic star HD 148937 is the only Galactic Of?p star surrounded by a nebula. The structure of this nebula is particularly complex and is composed, from the center out outwards, of a close bipolar ejecta nebula (NGC 6164/5), an ellipsoidal wind-blown shell, and a spherically symmetric Strömgren sphere. The exact formation process of this nebula and its precise relation to the star's evolution remain unknown. Methods. We analyzed infrared Spitzer IRS and far-infrared Herschel/PACS observations of the NGC 6164/5 nebula. The Herschel imaging allowed us to constrain the global morphology of the nebula. We also combined the infrared spectra with optical spectra of the central star to constrain its evolutionary status. We used these data to derive the abundances in the ejected material. To relate this information to the evolutionary status of the star, we also determined the fundamental parameters of HD 148937 using the CMFGEN atmosphere code. Results. The Hα image displays a bipolar or "8"-shaped ionized nebula, whilst the infrared images show dust to be more concentrated around the central object. We determine nebular abundance ratios of N/O = 1.06 close to the star, and N/O = 1.54 in the bright lobe constituting NGC 6164. Interestingly, the parts of the nebula located further from HD 148937 appear more enriched in stellar material than the part located closer to the star. Evolutionary tracks suggest that these ejecta have occured ∼ 1.2 − 1.3 and ∼ 0.6 Myrs ago, respectively. In addition, we derive abundances of argon for the nebula compatible with the solar values and we find a depletion of neon and sulfur. The combined analyses of the known kinematics and of the new abundances of the nebula suggest either a helical morphology for the nebula, possibly linked to the magnetic geometry, or the occurrence of a binary merger.

show abstract

Section: Introductionmentioning

confidence: 94%

Section: Kinematics Of the Nebulamentioning

confidence: 99%

Evolutionary status of the Of?p star HD 148937 and of its surrounding nebula NGC 6164/5

Mahy

Hutsemékers

Nazé

et al. 2017

A&A

View full text Add to dashboard Cite

show abstract

“…that are often periodically variable, small recurrent variations in brightness, abnormally bright X-ray emissions, and strong dipolar magnetic fields (see e.g. Nazé et al 2008b).…”

Section: Introductionmentioning

confidence: 99%

Photometric identification of the periods of the first candidate extragalactic magnetic massive stars

Nazé

Walborn

Morrell

et al. 2015

A&A

Self Cite

View full text Add to dashboard Cite

Galactic stars belonging to the Of?p category are all strongly magnetic objects exhibiting rotationally modulated spectral and photometric changes on timescales of weeks to years. Five candidate Of?p stars in the Magellanic Clouds have been discovered, notably in the context of ongoing surveys of their massive star populations. Here we describe an investigation of their photometric behaviour, revealing significant variability in all studied objects on timescales of one week to more than four years, including clearly periodic variations for three of them. Their spectral characteristics along with these photometric changes provide further support for the hypothesis that these are strongly magnetized O stars, analogous to the Of?p stars in the Galaxy.

show abstract

“…5 are plotted for a particular phase ϕ ≈ 0.3. In magnetic stars, the wind properties depend on the tilt of the magnetic field (e.g., ud-Doula et al 2009), therefore, the wind line profiles show rotational variability (Bjorkman et al 1994;Marcolino et al 2013;Nazé et al 2015). We tested the existence of the wind also in other phases with similar conclusions as for the phase ϕ ≈ 0.3.…”

Section: Stellar Wind Of Cu Virmentioning

confidence: 80%

HST/STIS analysis of the first main sequence pulsar CU Virginis

Krtička

Mikulášek

Henry

et al. 2019

A&A

View full text Add to dashboard Cite

Context. CU Vir has been the first main sequence star that showed regular radio pulses that persist for decades, resembling the radio lighthouse of pulsars and interpreted as auroral radio emission similar to that found in planets. The star belongs to a rare group of magnetic chemically peculiar stars with variable rotational period. Aims. We study the ultraviolet (UV) spectrum of CU Vir obtained using STIS spectrograph onboard the Hubble Space Telescope (HST) to search for the source of radio emission and to test the model of the rotational period evolution. Methods. We used our own far-UV and visual photometric observations supplemented with the archival data to improve the parameters of the quasisinusoidal long-term variations of the rotational period. We predict the flux variations of CU Vir from surface abundance maps and compare these variations with UV flux distribution. We searched for wind, auroral, and interstellar lines in the spectra. Results. The UV and visual light curves display the same long-term period variations supporting their common origin. New updated abundance maps provide better agreement with the observed flux distribution. The upper limit of the wind mass-loss rate is about 10 −12 M ⊙ yr −1 . We do not find any auroral lines. We find rotationally modulated variability of interstellar lines, which is most likely of instrumental origin. Conclusions. Our analysis supports the flux redistribution from far-UV to near-UV and visual domains originating in surface abundance spots as the main cause of the flux variability in chemically peculiar stars. Therefore, UV and optical variations are related and the structures leading to these variations are rigidly confined to the stellar surface. The radio emission of CU Vir is most likely powered by a very weak presumably purely metallic wind, which leaves no imprint in spectra.

show abstract

The changing UV and X-ray properties of the Of?p star CPD −28°2561

Cited by 22 publications

References 54 publications

Evolutionary status of the Of?p star HD 148937 and of its surrounding nebula NGC 6164/5

Evolutionary status of the Of?p star HD 148937 and of its surrounding nebula NGC 6164/5

Photometric identification of the periods of the first candidate extragalactic magnetic massive stars

HST/STIS analysis of the first main sequence pulsar CU Virginis

Contact Info

Product

Resources

About