Hot and cool: two emission-line stars with constrasting behaviours in the same XMM-<i>Newton</i>field

Nazé, Yaël; Rauw, Grégor; ud‐Doula, Asif

doi:10.1051/0004-6361/200913118

Cited by 6 publications

(4 citation statements)

References 45 publications

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“…It is associated with the X-ray source 1RXS J171502.4-333344 with L X /L bol = −3.10. A X-ray flare was detected by Nazé et al (2010). It was proposed by Malo et al (2013) as member of the association.…”

Section: -2mass J11515681+0731262mentioning

confidence: 99%

TheβPictoris association: Catalog of photometric rotational periods of low-mass members and candidate members

Messina

Millward²,

Buccino

et al. 2017

A&A

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Aims. We intended to compile the most complete catalog of bona fide members and candidate members of the β Pictoris association, and to measure their rotation periods and basic properties from our own observations, public archives, and exploring the literature. Methods. We carried out a multi-observatories campaign to get our own photometric time series and collected all archived public photometric data time series for the stars in our catalog. Each time series was analyzed with the Lomb-Scargle and CLEAN periodograms to search for the stellar rotation periods. We complemented the measured rotational properties with detailed information on multiplicity, membership, and projected rotational velocity available in the literature and discussed star by star. Results. We measured the rotation periods of 112 out of 117 among bona fide members and candidate members of the β Pictoris association and, whenever possible, we also measured the luminosity, radius, and inclination of the stellar rotation axis. This represents to date the largest catalog of rotation periods of any young loose stellar association. Conclusions. We provided an extensive catalog of rotation periods together with other relevant basic properties useful to explore a number of open issues, such as the causes of spread of rotation periods among coeval stars, evolution of angular momentum, and lithium-rotation connection.

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Section: -2mass J11515681+0731262mentioning

confidence: 99%

TheβPictoris association: Catalog of photometric rotational periods of low-mass members and candidate members

Messina

Millward²,

Buccino

et al. 2017

A&A

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“…Previously, two Oe stars have been observed in X-rays, HD 119682 (O9.7-B0 Ve 2 , Rakowski et al 2006) andHD 155806 (O7.5 IIIe, Nazé et al 2010). On the one hand, HD 155806 has a very soft X-ray spectrum with two plasma temperatures of kT = 0.2 and 0.6 keV, as well as broad emission lines and an emission level consistent with normal O-type stars (Nazé et al 2010). On the other hand, HD 119682 (O9.7e) displays a very hard X-ray spectrum with a dominant plasma component at kT ∼ 10 keV, making this object a so-called γ Cas analog (Rakowski et al 2006).…”

Section: Introductionmentioning

confidence: 99%

HD 45314: a newγ Cassiopeiae analog among Oe stars

Rauw

Nazé

Spano

et al. 2013

A&A

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Context. Oe stars possibly form an extension to higher temperatures of the Be phenomenon, but it is still unclear whether these stars have disks. Aims. X-ray spectra could provide hints for interactions of the star with a putative surrounding disk. Methods. We obtained XMM-Newton observations of two Oe stars, HD 45314 and HD 60848. Spectra and light curves were extracted and analysed. Optical spectra were also obtained to support the X-ray observations. Results. We find that both stars display very different X-ray properties. Whilst HD 60848 has an X-ray spectrum and emission level typical for its spectral type, HD 45314 displays a very hard X-ray emission, dominated by a thermal plasma with kT ∼ 21 keV. Furthermore, HD 45314 displays count rate variations by a factor 2 on timescales of ∼10 3 s and a high log L X L bol = −6.10 ± 0.03. Conclusions. The X-ray properties of HD 45314 indicate that this star is a new member of the class of γ Cas analogs, the first one among the original category of Oe stars.

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“…The bulk of its plasma is at a high temperature of 8 MK (Zhekov & Palla 2004). Nazé et al (2010a) do not detect a modulation of the X-ray flux in HD 155806 and report that its X-ray emission lines are broad. The bulk of its hot plasma has only 2 MK.…”

Section: X-ray Emission From Oe-type Starsmentioning

confidence: 81%

“…The bulk of its hot plasma has only 2 MK. The log L X /L bol = −6.75 for HD 155806, while log L X /L bol = −7.4 for ζ Oph (Oskinova et al 2006, Nazé et al 2010a. Clearly, larger observational samples are required to understand the link between the X-ray emission of Oe-type stars and their hypothetical circumstellar disks.…”

Section: X-ray Emission From Oe-type Starsmentioning

confidence: 99%

X-rays, clumping and stellar wind structures

Oskinova,

Hamann,

Ignace

et al. 2010

Preprint

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X-ray emission is ubiquitous among massive stars. In the last decade, X-ray observations revolutionized our perception of stellar winds but opened a Pandora's box of urgent problems. X-rays penetrating stellar winds suffer mainly continuum absorption, which greatly simplifies the radiative transfer treatment. The small and large scale structures in stellar winds must be accounted for to understand the X-ray emission from massive stars. The analysis of X-ray spectral lines can help to infer the parameters of wind clumping, which is prerequisite for obtaining empirically correct stellar mass-loss rates. The imprint of large scale structures, such as CIRs and equatorial disks, on the X-ray emission is predicted, and new observations are testing theoretical expectations. The X-ray emission from magnetic stars proves to be more diverse than anticipated from the direct application of the magnetically-confined wind model. Many outstanding questions about X-rays from massive stars will be answered when the models and the observations advance.

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Hot and cool: two emission-line stars with constrasting behaviours in the same XMM-Newtonfield

Cited by 6 publications

References 45 publications

TheβPictoris association: Catalog of photometric rotational periods of low-mass members and candidate members

TheβPictoris association: Catalog of photometric rotational periods of low-mass members and candidate members

HD 45314: a newγ Cassiopeiae analog among Oe stars

X-rays, clumping and stellar wind structures

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