Spatial Distribution and Kinematics of the Molecular Material Associated With Eta Carinae

Loinard, Laurent; Kamiński, Tomasz; Serra, P.; Menten, K. M.; Zapata, Luis A.; Rodrı́guez, Luis F.

doi:10.3847/1538-4357/833/1/48

Cited by 11 publications

(17 citation statements)

References 29 publications

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“…In MGE042.0787+00.5084 (hereafter MGE042), we also found a molecular torus in slow expansion, with similar dynamical ages [11]. Recently, η Carina was also the subject of molecular studies, where molecular material connected to the Homunculus and a more recent outburst were discovered [12][13][14][15][16].…”

supporting

confidence: 58%

NIKA2 observations around LBV stars Emission from stars and circumstellar material

2020

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Luminous Blue Variable (LBV) stars are evolved massive objects, previous to core-collapse supernova. LBVs are characterized by photometric and spectroscopic variability, produced by strong and dense winds, mass-loss events and very intense UV radiation. LBVs strongly disturb their surroundings by heating and shocking, and produce important amounts of dust. The study of the circumstellar material is therefore crucial to understand how these massive stars evolve, and also to characterize their effects onto the interstellar medium. The versatility of NIKA2 is a key in providing simultaneous observations of both the stellar continuum and the extended, circumstellar contribution. The NIKA2 frequencies (150 and 260 GHz) are in the range where thermal dust and free-free emission compete, and hence NIKA2 has the capacity to provide key information about the spatial distribution of circumstellar ionized gas, warm dust and nearby dark clouds; non-thermal emission is also possible even at these high frequencies. We show the results of the first NIKA2 survey towards five LBVs. We detected emission from four stars, three of them immersed in tenuous circumstellar material. The spectral indices show a complex distribution and allowed us to separate and characterize different components. We also found nearby dark clouds, with spectral indices typical of thermal emission from dust. Spectral indices of the detected stars are negative and hard to be explained only by free-free processes. In one of the sources, G79.29+0.46, we also found a strong correlation of the 1mm and 2mm continuum emission with respect to nested molecular shells at ≈1 pc from the LBV. The spectral index in this region clearly separates four components: the LBV star, a bubble characterized by free-free emission, and a shell interacting with a nearby infrared dark cloud.

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confidence: 58%

NIKA2 observations around LBV stars Emission from stars and circumstellar material

2020

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“…2.4). Variability at a level of ≈25% has also been seen in the 3 mm continuum between the ALMA data by Abraham et al (2014) and Australia Telescope Compact Array observations by Loinard et al (2016), indicated to be lower 1.67 yr after the ALMA observations, which were taken near periastron.…”

Section: While We Have No Indications Of Background Contam-mentioning

confidence: 72%

“…This could indicate even higher increases in submillimeter emission correlated with the radio cycle, and it is also in phase with the low-amplitude variability indicated (albeit tenuously) in our HIFI continuum measurements (Section 2.4). Variability at a level of ≈25% has also been seen in the 3 mm continuum between the ALMA data by Abraham et al (2014) and Australia Telescope Compact Array observations by Loinard et al (2016), indicated to be lower 1.67 yr after the ALMA observations, which were taken near periastron.…”

Section: The Full Ir To Millimeter Sed Of Hcarinaementioning

confidence: 88%

η Carinae's Dusty Homunculus Nebula from Near-infrared to Submillimeter Wavelengths: Mass, Composition, and Evidence for Fading Opacity

Morris

Gull

Hillier

et al. 2017

ApJ

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Infrared observations of the dusty, massive Homunculus Nebula around the luminous blue variable η Carinae are crucial to characterize the mass-loss history and help constrain the mechanisms leading to the great eruption. We present the 2.4-670 μm spectral energy distribution, constructed from legacy Infrared Space Observatory observations and new spectroscopy obtained with the Herschel Space Observatory. Using radiative transfer modeling, we find that the two best-fit dust models yield compositions that are consistent with CNO-processed material, with iron, pyroxene and other metal-rich silicates, corundum, and magnesium-iron sulfide in common. Spherical corundum grains are supported by the good match to a narrow 20.2 μm feature. Our preferred model contains nitrides AlN and Si 3 N 4 in low abundances. Dust masses range from 0.25 to 0.44tot in both cases, due to an expected high Fe gas-to-dust ratio. The bulk of dust is within a ´ 5 7 central region. An additional compact feature is detected at 390 μm. We obtain L IR = 2.96×10 6  L , a 25% decline from an average of mid-IR photometric levels observed in 1971-1977. This indicates a reduction in circumstellar extinction in conjunction with an increase in visual brightness, allowing 25%-40% of optical and UV radiation to escape from the central source. We also present an analysis of 12 CO and 13 CO J=5-4 through 9-8 lines, showing that the abundances are consistent with expectations for CNO-processed material. The [ 12 C II] line is detected in absorption, which we suspect originates in foreground material at very low excitation temperatures.

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“…) suggests that this line may actually be H recombination. Several additional molecules have since been detected via single-dish observations from the inner regions of the Homunculus (Loinard et al 2012(Loinard et al , 2016Morris et al 2017), and have also been attributed to the dusty torus seen in the IR. CO emission has also been detected in the circumstellar environments of other LBVs, including AG Carinae and HR Carinae (Nota et al 2002;McGregor et al 1988).…”

Section: Introductionmentioning

confidence: 99%

A disrupted molecular torus around Eta Carinae as seen in 12CO with ALMA

Smith

Ginsburg

Bally

2017

Monthly Notices of the Royal Astronomical Society

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We present Atacama Large Millimeter Array (ALMA) observations of 12 CO 2−1 emission from circumstellar material around the massive star η Carinae. These observations reveal new structural details about the cool equatorial torus located ∼4000 au from the star. The CO torus is not a complete azimuthal loop, but rather, is missing its near side, which appears to have been cleared away. The missing material matches the direction of apastron in the eccentric binary system, making it likely that η Car's companion played an important role in disrupting portions of the torus soon after ejection. Molecular gas seen in ALMA data aligns well with the cool dust around η Car previously observed in mid-infrared (IR) maps, whereas hot dust resides at the inner surface of the molecular torus. The CO also coincides with the spatial and velocity structure of near-IR H 2 emission. Together, these suggest that the CO torus seen by ALMA is actually the pinched waist of the Homunculus polar lobes, which glows brightly because it is close to the star and warmer than the poles. The near side of the torus appears to be a blowout, associated with fragmented equatorial ejecta. We discuss implications for the origin of various features northwest of the star. CO emission from the main torus implies a total gas mass in the range of 0.2 -1 M ⊙ (possibly up to 5 M ⊙ or more, although with questionable assumptions). Deeper observations are needed to constrain CO emission from the cool polar lobes.

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Spatial Distribution and Kinematics of the Molecular Material Associated With Eta Carinae

Cited by 11 publications

References 29 publications

NIKA2 observations around LBV stars Emission from stars and circumstellar material

NIKA2 observations around LBV stars Emission from stars and circumstellar material

η Carinae's Dusty Homunculus Nebula from Near-infrared to Submillimeter Wavelengths: Mass, Composition, and Evidence for Fading Opacity

A disrupted molecular torus around Eta Carinae as seen in 12CO with ALMA

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