Exploring the multifaceted circumstellar environment of the luminous blue variable HR Carinae

Buemi, C. S.; Trigilio, C.; Leto, P.; Umana, G.; Ingallinera, A.; Cavallaro, F.; Cerrigone, L.; Agliozzo, C.; Bufano, F.; Riggi, S.; Molinari, S.; Schillirò, F.

doi:10.1093/mnras/stw3074

Cited by 11 publications

(17 citation statements)

References 49 publications

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“…The central star was later catalogued as a candidate LBV by means of near-infrared spectroscopy, which revealed strong hydrogen emission lines (including Pfund and Brackett series) and several metal lines (Mg ii, Na ii, Fe ii) usually found in other LBV spectra (Flagey et al 2014). On the other hand, recent 6-cm VLA observations (Ingallinera et al 2016) unveiled a clumpy radio nebula strongly coupled to the infrared shell, with hints of a differentiated spectral index, as in other well known LBV sources such as HR Car (Buemi et al 2017).…”

Section: Introductionmentioning

confidence: 93%

A slowly expanding torus associated with the candidate LBV MGE 042.0787+00.5084

Bordiu

Rizzo

Ritacco

2018

Monthly Notices of the Royal Astronomical Society

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The luminous blue variable (LBV) phase is a poorly understood stage in the evolution of high mass stars, characterized for its brevity and instability. The surroundings of LBV stars are excellent test beds to study their dense stellar winds and eruptive mass-loss events. Aiming to improve our knowledge of the LBV phase, we observed the J = 1 → 0 and J = 2 → 1 lines of CO and 13 CO in a field of 1. 5 × 1. 5 around the recently identified candidate LBV MGE 042.0787+00.5084, using the IRAM 30-m radio telescope. We report the first detection of molecular emission associated with this source, tracing a structure with an evident circumstellar distribution. Morphology and kinematics of the gas can be explained by an expanding torus, a structure that may have originated from stellar ejecta or the action of stellar winds onto the parent molecular cloud. We derive the physical properties of the gas by means of LTE and non-LTE line modelling, obtaining densities of H 2 in the order of 10 3 cm −3 and kinetic temperatures below 100 K. In addition, we build a kinematic model to reproduce the structure and velocity fields of the gas, which is in good agreement with the observations. We estimate a total molecular gas mass of 0.6 ± 0.1 M and a dynamical age of 6 × 10 4 years, leading to an average mass-loss rate of 0.8-1.2×10 −5 M yr −1 .

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Section: Introductionmentioning

confidence: 93%

A slowly expanding torus associated with the candidate LBV MGE 042.0787+00.5084

Bordiu

Rizzo

Ritacco

2018

Monthly Notices of the Royal Astronomical Society

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“…The morphologies of some nebulae are consistent with symmetric mass loss (e.g., Gal 79.29+0.46, LHA 120-S 61, Higgs et al 1994;Weis 2003;Umana et al 2011;Agliozzo et al 2012Agliozzo et al , 2014Agliozzo et al , 2017a. However, the majority of the observed nebulae have a bipolar morphology (e.g., Weis 2011), indicating aspherical mass loss (e.g., Gal 026.47+0.02, Umana et al 2012) or an external shaping mechanism (e.g., IRAS 18576+0341, HR Car, Umana et al 2005;Buemi et al 2010Buemi et al , 2017. Usually, bipolar or equatorial mass losses have been proposed.…”

Section: Introductionmentioning

confidence: 81%

The Luminous Blue Variable RMC 127 as Seen with ALMA and ATCA

Agliozzo

Trigilio

Pignata

et al. 2017

ApJ

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We present ALMA and ATCA observations of the luminous blue variable RMC 127. The radio maps show for the first time the core of the nebula and evidence that the nebula is strongly asymmetric with a Z-pattern shape. Hints of this morphology are also visible in the archival Hubble Space Telescope Ha image, which overall resembles the radio emission. The emission mechanism in the outer nebula is optically thin free-free in the radio. At high frequencies, a component of point-source emission appears at the position of the star, up to the ALMA frequencies. The rising flux density distribution (S µ -( ). We examine different scenarios to explain this excess of thermal emission from the wind and show that this can arise from a bipolar outflow, supporting the suggestion by other authors that the stellar wind of RMC 127 is aspherical. We fit the data with two collimated ionized wind models, and we find that the mass-loss rate can be a factor of two or more smaller than in the spherical case. We also fit the photometry obtained by IR space telescopes and deduce that the mid-to far-IR emission must arise from extended, cool ( 80 K ) dust within the outer ionized nebula. Finally, we discuss two possible scenarios for the nebular morphology: the canonical single-star expanding shell geometry and a precessing jet model assuming the presence of a companion star.

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“…This appearance well distinguishes massive evolved stars from other kind of Galactic objects like H II regions or PNe. We also showed that these objects can have a differentiated spectral index (like HR Car; Buemi et al 2017). Following Ingallinera et al (2016) we searched for massive evolved candidates in the SCORPIO field, looking for a radio nebula with a central object.…”

Section: Luminous Blue Variable and Wolf-rayet Starsmentioning

confidence: 99%

Study of the Galactic radio sources in the SCORPIO survey resolved by ATCA at 2.1 GHz

Ingallinera

Umana

Trigilio

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We present a catalogue of a large sample of extended radio sources in the SCORPIO field, observed and resolved by the Australia Telescope Compact Array. SCORPIO, a pathfinder project for addressing the early operations of the Australia SKA Pathfinder, is a survey of ∼ 5 square degrees between 1.4 and 3.1 GHz, centered at l = 343.5 • , b = 0.75 • and with an angular resolution of about 10 arcsec. It is aimed at understanding the scientific and technical challenges to be faced by future Galactic surveys. With a mean sensitivity around 100 µJy beam −1 and the possibility to recover angular scales at least up to 4 arcmin, we extracted 99 extended sources, 35 of them detected for the first time. Among the 64 known sources 55 had at least a tentative classification in literature. Studying the radio morphology and comparing the radio emission with infrared we propose as candidates 6 new H II regions, 2 new planetary nebulae, 2 new luminous blue variable or Wolf-Rayet stars and 3 new supernova remnants. This study provides an overview of the potentiality of future radio surveys in terms of Galactic source extraction and characterization and a discussion on the difficulty to reduce and analyze interferometric data on the Galactic plane.

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Exploring the multifaceted circumstellar environment of the luminous blue variable HR Carinae

Cited by 11 publications

References 49 publications

A slowly expanding torus associated with the candidate LBV MGE 042.0787+00.5084

A slowly expanding torus associated with the candidate LBV MGE 042.0787+00.5084

The Luminous Blue Variable RMC 127 as Seen with ALMA and ATCA

Study of the Galactic radio sources in the SCORPIO survey resolved by ATCA at 2.1 GHz

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