MWC 324: A young star

Abstract. We present a new catalogue of symbiotic stars. In our list we include 188 symbiotic stars as well as 30 objects suspected of being symbiotic. For each star, we present basic observational material: coordinates, V and K magnitudes, ultraviolet (UV), infrared (IR), X-ray and radio observations. We also list the spectral type of the cool component, the maximum ionization potential observed, references to finding charts, spectra, classifications and recent papers discussing the physical parameters and nature of each object. Moreover, we present the orbital photometric ephemerides and orbital elements of known symbiotic binaries, pulsational periods for symbiotic Miras, Hipparcos parallaxes and information about outbursts and flickering.

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“…Reported as symbiotic in [147], possibly after suggestion in [34]. It is, however, a high-mass X-ray binary with a Be star donor [51,32].…”

Section: Cammentioning

confidence: 99%

A catalogue of symbiotic stars

Belczyński

Mikołajewska

Munari

et al. 2000

Astron. Astrophys. Suppl. Ser.

378

407

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“…Both photometric (e.g. Bergner et al 1995;Zickgraf et al 1996) and spectroscopic (e.g. Zickgraf 2003) variability have been observed in these stars but to date these have not been unambiguously associated with characteristic LBV excursions or eruptions.…”

Section: The Mid-late B Super-/hypergiantsmentioning

confidence: 99%

A serendipitous survey for variability amongst the massive stellar population of Westerlund 1

Clark¹,

Ritchie

Negueruela

2010

A&A

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Aims. Massive stars are known to demonstrate significant spectroscopic and photometric variability over a wide range of timescales. However the physical mechanisms driving this behaviour remain poorly understood. Westerlund 1 presents an ideal laboratory for studying these processes in a rich, coeval population of post-main sequence stars and we present a pathfinding study aimed at characterising their variability. Methods. To do this we utilised the large body of spectroscopic and photometric data that has accumulated for Wd1 during the past decade of intensive studies, supplemented with the sparser historical observations extending back to the early 1960s. Results. Despite the heterogeneous nature of this dataset, we were able to identify both spectroscopic and photometric variability amongst every class of evolved massive star present within Wd 1. Spectroscopic variability attributable to both wind asphericity and photospheric pulsations was present amongst both the hot and cool hypergiants and the former, also with the Wolf Rayets. Given the limitations imposed by the data, we were unable to determine the physical origin of the wind structure inferred for the OB supergiants, noting that it was present in both single pulsating and binary stars. In contrast we suspect that the inhomogineities in the winds of the Wolf Rayets are driven by binary interactions and, conversely, by pulsations in at least one of the cool hypergiants. Photospheric pulsations were found for stars ranging from spectral types as early as O9 I through to the mid F Ia + yellow hypergiants -with a possible dependence on the luminosity class amongst the hot supergiants. The spectroscopically variable red supergiants (M2-5 Ia) are also potential pulsators but require further observations to confirm this hypothesis. Given these findings it was therefore rather surprising that, with the exception of W243, no evidence of the characteristic excursions of both luminous blue variables and yellow hypergiants was found. Nevertheless, future determination of the amplitude and periodicity of these pulsations as a function of temperature, luminosity and evolutionary state holds out the tantalising possibility of constraining the nature of the physical mechanisms driving the instabilities that constrain and define stellar evolution in the upper reaches of the HR diagram. Relating to this, the lack of secular evolution amongst the cool hypergiants and the presence of both high-luminosity yellow hypergiants and red supergiants within Wd1 potentially place strong constraints on post-main sequence evolutionary pathways, with the latter result apparently contradicting current theoretical predictions for >25 M stars at solar metallicites.

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“…Optical and mid-IR photometry for this object was published by Shevchenko (1989), Bergner et al (1993) and Bergner et al (1995). Heckert & Zeilik (1981) found a significant degree of polarization in the IR (the degree of polarization in the JHK bands is about 2%−3%).…”

Section: Mwc 137mentioning

confidence: 99%

Polarimetry of southern peculiar early–type stars

Yudin

Evans

1998

Astron. Astrophys. Suppl. Ser.

Self Cite

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Abstract. We present and discuss optical polarimetry of a large group (60 objects) of peculiar early-type stars (Herbig Ae/Be stars and candidate members, B[e] stars, extreme emission line objects etc.). Most were taken from "A new catalogue of members and candidate members of Herbig Ae/Be stellar group" The et al. (1994). For 40 out of the 60 objects polarization was measured for the first time. On the basis of the data we draw conclusions about the circumstellar shell configuration and orientation for several objects. Polarimetric variability on different timescales (minutes . . . hours . . . days) was investigated, as well as comparison with earlier measurements to investigate variability over longer time-scales. No circular polarization was detected to a 5σ level in most of the investigated stars. Polarimetric data obtained here as well as data available from the literature were analyzed from the point of investigating the evolutionary status of the objects. The relationship between the polarimetric and photometric data was also investigated.

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MWC 324: A young star

Cited by 29 publications

References 9 publications

A catalogue of symbiotic stars

A catalogue of symbiotic stars

A serendipitous survey for variability amongst the massive stellar population of Westerlund 1

Polarimetry of southern peculiar early–type stars

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