Chandra spectral measurements of the O supergiant ζ Puppis indicate a surprising increase in the wind mass-loss rate over 18 yr

David H Cohen; Jiaming Wang; Véronique Petit; Maurice A Leutenegger; Lamiaa Dakir; Chloe Mayhue; Alexandre David-Uraz

doi:10.1093/mnras/staa3124

Chandra spectral measurements of the O supergiant ζ Puppis indicate a surprising increase in the wind mass-loss rate over 18 yr

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3124 ◽

2020 ◽

Vol 499 (4) ◽

pp. 6044-6052

Author(s):

David H Cohen ◽

Jiaming Wang ◽

Véronique Petit ◽

Maurice A Leutenegger ◽

Lamiaa Dakir ◽

...

Keyword(s):

Mass Loss ◽

Emission Line ◽

Loss Rate ◽

Mass Loss Rate ◽

Model Fitting ◽

Line Emission ◽

Long Wavelength ◽

Dependent Absorption ◽

The Individual ◽

Cold Wind

ABSTRACT New long Chandra grating observations of the O supergiant ζ Pup show not only a brightening of the X-ray emission line flux of 13 per cent in the 18 yr since Chandra’s first observing cycle, but also clear evidence – at more than 4σ significance – of increased wind absorption signatures in its Doppler-broadened line profiles. We demonstrate this with non-parametric analysis of the profiles as well as Gaussian fitting and then use line-profile model fitting to derive a mass-loss rate of 2.47 ± 0.09 × 10−6${\mathrm{M_{\odot }~{\mathrm{y}r^{-1}}}}$, which is a 40 per cent increase over the value obtained from the cycle 1 data. The increase in the individual emission line fluxes is greater for short-wavelength lines than long-wavelength lines, as would be expected if a uniform increase in line emission is accompanied by an increase in the wavelength-dependent absorption by the cold wind in which the shock-heated plasma is embedded.

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The enigmatic binary system HD 5980

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz808 ◽

2019 ◽

Vol 486 (1) ◽

pp. 725-742 ◽

Cited By ~ 3

Author(s):

D John Hillier ◽

Gloria Koenigsberger ◽

Yaël Nazé ◽

Nidia Morrell ◽

Rodolfo H Barbá ◽

...

Keyword(s):

Mass Loss ◽

Emission Line ◽

Loss Rate ◽

Mass Loss Rate ◽

Phase Dependence ◽

Wind Speeds ◽

Line Intensities ◽

Orbital Phase ◽

Emission Line Spectrum ◽

Luminous Blue Variable

Abstract The Small Magellanic Cloud multiple system HD 5980 contains a luminous blue variable (LBV) that underwent a major eruption in 1994, and whose current spectrum is that of a hydrogen-rich Wolf–Rayet (WR) star. Since the eruption, the wind mass-loss rate has been declining while wind speeds have been steadily increasing. Observations obtained in 2014 when Star A (the LBV) eclipses Star B indicate that the fitted mass-loss rate and luminosity have reached the lowest values ever determined for such spectra: $\dot{M}$ = 4.5 × 10−5$\mathrm{M}_\odot \, \hbox{yr}^{-1}$, L = 1.7 × 106 L⊙. In addition, the radius of the LBV’s continuum-emitting region is similar to that derived from the eclipse light curves of the late 1970s. Hence, it appears to have attained a similar ‘low’ state to that of the late 1970s. While a good fit to the emission spectrum is obtained using a cmfgen model, there are discrepancies in the UV. In particular, the extent of the observed absorption profiles is ∼1000 km s−1 greater than predicted by the emission-line intensities. Further, HST UV observations obtained in 2016, when Star A is eclipsed by Star B, show unusual P Cygni profiles that are not easily explained. Surprisingly the 2016 emission-line spectrum is similar to that at the opposite eclipse obtained in 2014. The complex UV profiles are likely to arise as a consequence of the dynamics of the wind–wind collision and radiative braking, both of which will cause significant departures from spherical symmetry, and have a strong orbital phase dependence. However, other scenarios, such as intrinsically aspherical winds, cannot be ruled out.

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Core-halo structures in the 12CO emission of CIT 6, AFGL 618 and IRAS 21282+5050

Symposium - International Astronomical Union ◽

10.1017/s0074180900131341 ◽

1997 ◽

Vol 180 ◽

pp. 359-359

Author(s):

M. Meixner ◽

M.T. Campbell ◽

W. J. Welch ◽

L. Likkel ◽

M. Tafalla

Keyword(s):

Mass Loss ◽

Spatial Resolution ◽

Planetary Nebula ◽

Loss Rate ◽

Mass Loss Rate ◽

Line Emission ◽

Carbon Star ◽

The Core ◽

Evolved Stars ◽

Transfer Modelling

We present full synthesis 12CO J= 1–0 line emission images of three carbon rich evolved stars: CIT 6, AFGL 618 and IRAS 21282+5050. Each of these objects represents a different stage of evolution: CIT 6 is a carbon star still on the AGB, AFGL 618 is a transition object, and IRAS 21282+5050 is a young planetary nebula. Common to all three sources, we find what appears to be two mass loss components: a bright “core” located at the center of the source and a fainter “halo” surrounding the core (see Table below for observed characteristics). We speculate that the bright core was created by a more recent and higher mass loss rate wind than the fainter surrounding halo. However, concrete support for this idea awaits radiative transfer modelling of the 12CO that we are currently pursuing. Our full synthesis data are combined from millimeter interferometry using the Berkeley–Illinois–Maryland millimeter array (BIMA) and single dish maps using the NRAO 12m. We find that full-synthesis imaging, which combines the sensitivity of single dish and the spatial resolution of interferometry, is the only means to reveal such core-halo structures.

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Is AS 431 a Superluminous WR Star?

Symposium - International Astronomical Union ◽

10.1017/s0074180900148934 ◽

1986 ◽

Vol 116 ◽

pp. 229-230

Author(s):

D. J. Stickland ◽

C. Lloyd ◽

A. J. Willis

Keyword(s):

Point Source ◽

Mass Loss ◽

Emission Line ◽

Loss Rate ◽

Near Infrared ◽

Mass Loss Rate ◽

X Ray ◽

Radio Data ◽

General Properties ◽

Order Of Magnitude

The recent study by Caillault et al. (1985) has shown the emission-line star AS 431 (= WR 147) to be a strong X-ray source and moderately strong radio emitter. Combining optical, near-infrared and radio data, they deduced that its mass loss rate was ∼ 4 × 10−4 M⊙yr−1, an order of magnitude greater than is normal for WR stars. They also suggested that it would show up in the IRAS survey and that such data would help to elucidate whether its extreme reddening had a significant circumstellar component. To investigate this possibility and to study the general properties of the object, we have raided the IRAS Point Source Catalogue.

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CO envelope of the symbiotic star R Aquarii seen by ALMA

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833394 ◽

2018 ◽

Vol 616 ◽

pp. A61 ◽

Cited By ~ 8

Author(s):

S. Ramstedt ◽

S. Mohamed ◽

T. Olander ◽

W. H. T. Vlemmings ◽

T. Khouri ◽

...

Keyword(s):

Mass Loss ◽

Spatial Resolution ◽

White Dwarf ◽

Loss Rate ◽

Mass Loss Rate ◽

Line Emission ◽

High Energy ◽

Small Sample ◽

Symbiotic Star ◽

Binary Separation

The symbiotic star R Aqr is part of a small sample of binary AGB stars observed with the Atacama Large Millimeter/submillimeter Array (ALMA). The sample stars are: R Aqr, Mira, W Aql, and π1 Gru. The sample covers a range in binary separation and wind properties, where R Aqr is the source with the smallest separation. The R Aqr binary pair consists of an M-type AGB star and a white dwarf at a separation of 45 mas, equivalent to about 10 AU at 218 pc. The aim of the ALMA study is to investigate the dependence of the wind shaping on the binary separation and to provide constraints for hydrodynamical binary interaction models. R Aqr is particularly interesting as the source with the smallest separation and a complex circumstellar environment that is strongly affected by the interaction between the two stars and by the high-energy radiation resulting from this interaction and from the hot white dwarf companion. The CO(J = 3 →2) line emission has been observed with ALMA at ~0.5′′ spatial resolution. The CO envelope around the binary pair is marginally resolved, showing what appears to be a rather complex distribution. The outer radius of the CO emitting region is estimated from the data and found to be about a factor of 10 larger than previously thought. This implies an average mass-loss rate during the past ~100 yr of Ṁ ≈ 2×10−7 M⊙ yr−1, a factor of 45 less than previous estimates. The channel maps are presented and the molecular gas distribution is discussed and set into the context of what was previously known about the system from multiwavelength observations. Additional molecular line emission detected within the bandwidth covered by the ALMA observations is also presented. Because of the limited extent of the emission, firm conclusions about the dynamical evolution of the system will have to wait for higher spatial resolution observations. However, the data presented here support the assumption that the mass-loss rate from the Mira star strongly varies and is focused on the orbital plane.

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Circumstellar environment of the M-type AGB star R Doradus

Astronomy and Astrophysics ◽

10.1051/0004-6361/201732470 ◽

2018 ◽

Vol 615 ◽

pp. A8 ◽

Cited By ~ 13

Author(s):

E. De Beck ◽

H. Olofsson

Keyword(s):

Mass Loss ◽

Loss Rate ◽

Mass Loss Rate ◽

Line Emission ◽

Asymptotic Giant Branch ◽

Emission Lines ◽

High Mass ◽

Spectral Features ◽

High Mass Loss ◽

Spectral Scan

Context. Our current insights into the circumstellar chemistry of asymptotic giant branch (AGB) stars are largely based on studies of carbon-rich stars and stars with high mass-loss rates. Aims. In order to expand the current molecular inventory of evolved stars we present a spectral scan of the nearby, oxygen-rich star R Dor, a star with a low mass-loss rate (~2 × 10−7 M⊙ yr−1). Methods. We carried out a spectral scan in the frequency ranges 159.0–321.5 GHz and 338.5–368.5 GHz (wavelength range 0.8–1.9 mm) using the SEPIA/Band-5 and SHeFI instruments on the APEX telescope and we compare it to previous surveys, including one of the oxygen-rich AGB star IK Tau, which has a high mass-loss rate (~5 ×10−6 M⊙ yr−1). Results. The spectrum of R Dor is dominated by emission lines of SO2 and the different isotopologues of SiO. We also detect CO, H2O, HCN, CN, PO, PN, SO, and tentatively TiO2, AlO, and NaCl. Sixteen out of approximately 320 spectral features remain unidentified. Among these is a strong but previously unknown maser at 354.2 GHz, which we suggest could pertain to H2SiO, silanone. With the exception of one, none of these unidentified lines are found in a similarly sensitive survey of IK Tau performed with the IRAM 30 m telescope. We present radiative transfer models for five isotopologues of SiO (28SiO, 29SiO, 30SiO, Si17O, Si18O), providing constraints on their fractional abundance and radial extent. We derive isotopic ratios for C, O, Si, and S and estimate that, based on our results for 17O/18O, R Dor likely had an initial mass in the range 1.3–1.6 M⊙, in agreement with earlier findings based on models of H2O line emission. From the presence of spectral features recurring in many of the measured thermal and maser emission lines we tentatively identify up to five kinematical components in the outflow of R Dor, indicating deviations from a smooth, spherical wind.

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