M. Koutoulaki

Dublin Institute For Advanced Studies

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A. Caratti o Garatti

Astronomical Observatory of Capodimonte

R. García López

University College Dublin

J. Sánchez-Bermúdez

Universidad Nacional Autónoma de México

T. P. Ray

Dublin Institute For Advanced Studies

S. Lacour

Janssen (France)

J.-B. Le Bouquin

Centre National de la Recherche Scientifique

Jean-Philippe Berger

Centre National de la Recherche Scientifique

G. Perrin

University of Pennsylvania

P. Kervella

Qualissima (France)

E. F. van Dishoeck

Leiden University

Cooperative Institutions

Max Planck Society

194

Centre National de la Recherche Scientifique

153

Max Planck Institute for Extraterrestrial Physics

141

Max Planck Institute for Astronomy

116

European Southern Observatory

110

Laboratoire d’études spatiales et d’instrumentation en astrophysique

Université Grenoble Alpes

Observatoire de Paris

Sorbonne Université

Université Paris Cité

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Evidence for Jet/Outflow Shocks Heating the Environment around the Class I Protostellar Source Elias 29: FAUST XXI

The Astrophysical Journal (2025)

Yoko Oya Eri Saiga A. Miotello M. Koutoulaki Doug Johnstone

Abstract We have observed the late Class I protostellar source Elias 29 at a spatial resolution of 70 au with the Atacama Large Millimeter/submillimeter Array as part of the FAUST Large Program. We focus on the line emission of SO, while that of 34 SO, C 18 O, CS, SiO, H 13 CO + , and DCO + are used supplementarily. The spatial distribution of the SO rotational temperature ( T rot (SO)) is evaluated by using the intensity ratio of its two rotational excitation lines. Besides in the vicinity of the protostar, two hot spots are found at a distance of 500 au from the protostar; T rot (SO) locally rises to 53 − 15 + 25 K at the interaction point of the outflow and the southern ridge, and 72 − 29 + 66 K within the southeastern outflow probably due to a jet-driven bow shock. However, the SiO emission is not detected at these hot spots. It is likely that active gas accretion through the disk-like structure and onto the protostar still continues even at this evolved protostellar stage, at least sporadically, considering the outflow/jet activities and the possible infall motion previously reported. Interestingly, T rot (SO) is as high as 20–30 K even within the quiescent part of the southern ridge apart from the protostar by 500–1000 au without clear kinematic indication of current outflow/jet interactions. Such a warm condition is also supported by the low deuterium fractionation ratio of HCO + estimated by using the H 13 CO + and DCO + lines. The B-type star HD147889 ∼0.5 pc away from Elias 29, previously suggested as a heating source for this region, is likely responsible for the warm condition of Elias 29.

FAUST

Outflow

Protostar

10.3847/1538-4357/adabe7

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The Betelgeuse Project: constraints from rotation

Monthly Notices of the Royal Astronomical Society (2016)

J. C. Wheeler Sarafina Nance M. C. Díaz Sinclair. Smith Joanne V. Hickey

In order to constrain the evolutionary state of the red supergiant Betelgeuse, we have produced a suite of models with ZAMS masses from 15 to 25 Msun in intervals of 1 Msun including the effects of rotation. The models were computed with the stellar evolutionary code MESA. For non-rotating models we find results that are similar to other work. It is somewhat difficult to find models that agree within 1 sigma of the observed values of R, Teff and L, but modestly easy within 3 sigma uncertainty. Incorporating the nominal observed rotational velocity, ~15 km/s, yields significantly different, and challenging, constraints. This velocity constraint is only matched when the models first approach the base of the red supergiant branch (RSB), having crossed the Hertzsprung gap, but not yet having ascended the RSB and most violate even generous error bars on R, Teff and L. Models at the tip of the RSB typically rotate at only ~0.1 km/s, independent of any reasonable choice of initial rotation. We discuss the possible uncertainties in our modeling and the observations, including the distance to Betelgeuse, the rotation velocity, and model parameters. We summarize various options to account for the rotational velocity and suggest that one possibility is that Betelgeuse merged with a companion star of about 1 Msun as it ascended the RSB, in the process producing the ring structure observed at about 7' away. A past coalescence would complicate attempts to understand the evolutionary history and future of Betelgeuse.

Coalescence (physics)

10.1093/mnras/stw2893

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Citations (30)

RW Aur A: SpeX Spectral Evidence for Differentiated Planetesimal Formation, Migration, and Destruction in an ∼3 Myr Old Excited CTTS System

The Astrophysical Journal (2022)

C. M. Lisse Michael L. Sitko S. J. Wolk Hans Moritz Günther S. Brittain

We present 2007 - 2020 SpeX VISNIR spectral monitoring of the highly variable RW Aur A CTTS. We find direct evidence for a highly excited, IR bright, asymmetric, and time variable system. Comparison of the spectral and temporal trends found determines 5 different components: (1) a stable continuum from 0.7 - 1.3 um, with approx color temperature 4000K, produced by the CTTS photospheric surface; (2) variable hydrogen emission lines emitted from hot excited hydrogen in the CTTSs protostellar atmosphere/accretion envelope; (3) hot CO gas in the CTTSs protostellar atmosphere/accretion envelope; (4) highly variable 1.8-5.0 um thermal continuum emission with color temperature ranging from 1130 to 1650K, due to a surrounding accretion disk that is spatially variable and has an inner wall at r = 0.04 AU and T = 1650K, and outer edges at approx 1200K; and (5) transient, bifurcated signatures of abundant Fe II + associated SI, SiI, and SrI in the systems jet structures. The bifuracted signatures first appeared in 2015, but these collapsed and disappeared into a small single peak protostellar atmosphere feature by late 2020. The temporal evolution of RW Aur As spectral signatures is consistent with a dynamically excited CTTS system forming differentiated Vesta-sized planetesimals in an asymmetric accretion disk and migrating them inward to be destructively accreted. By contrast, nearby, coeval binary companion RW Aur B evinces only (1) a stable WTTS photospheric continuum from 0.7 - 1.3 um + (3) cold CO gas in absorption + (4) stable 1.8-5.0 um thermal disk continuum emission with color temperature approx 1650K.

10.3847/1538-4357/ac51e0

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The sharpest view on the high-mass star-forming region S255IR

Astronomy and Astrophysics (2023)

R. Fedriani A. Caratti o Garatti R. Cesaroni Jonathan C. Tan B. Stecklum

Context. Massive stars have an impact on their surroundings from early in their formation until the end of their lives. However, very little is known about their formation. Episodic accretion may play a crucial role in the process, but only a handful of observations have reported such events occurring in massive protostars. Aims. We aim to investigate the outburst event from the high-mass star-forming region S255IR where the protostar NIRS3 recently underwent an accretion outburst. We follow the evolution of this source both in photometry and morphology of its surroundings. Methods. We performed near infrared adaptive optics observations on the S255IR central region using the Large Binocular Telescope in the K s broadband as well as the H 2 and Brγ narrow-band filters with an angular resolution of ~07″.06, close to the diffraction limit. Results. We discovered a new near infrared knot north-east of NIRS3 that we interpret as a jet knot that was ejected during the last accretion outburst and observed in the radio regime as part of a follow-up after the outburst. We measured a mean tangential velocity for this knot of 450 ± 50 km s −1 . We analysed the continuum-subtracted images from H 2 , which traces jet-shocked emission, and Brγ, which traces scattered light from a combination of accretion activity and UV radiation from the central massive protostar. We observed a significant decrease in flux at the location of NIRS3, with K = 13.48 mag being the absolute minimum in the historic series. Conclusions. Our observations strongly suggest a scenario where the episodic accretion is followed by an episodic ejection response in the near infrared, as was seen in the earlier radio follow-up. The ~2 µm photometry from the past 30 yr suggests that NIRS3 might have undergone another outburst in the late 1980s, making it the first massive protostar with such evidence observed in the near infrared.

Protostar

10.1051/0004-6361/202346736

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Citations (6)

Images at the Highest Angular Resolution with GRAVITY: The Case of η Carinae

HAL (Le Centre pour la Communication Scientifique Directe) (2019)

R. Abuter M. Accardo T. Adler A. Amorim Narsireddy Anugu

10.18727/0722-6691/5170

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Citations (1)

A measure of the size of the magnetospheric accretion region in TW Hydrae

Nature (2020)

R. García López A. Natta A. Caratti o Garatti T. P. Ray R. Fedriani

10.1038/s41586-020-2613-1

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Citations (39)

Calculating the dust properties of the class I source Elias29

M. Koutoulaki L. Testi A. Miotello László Szücs Satoshi Yamamoto

A first step towards understanding planetary formation is the characterisation of the structure and evolution of protoplanetary discs. A variety of planetary systems has been discovered in recent years and it likely depends on the early history of their formation. Thus understanding the chemical composition of early solar-like protostars is crucial. To be able to study the lines in detail though, a good knowledge of the dust properties and in particular the optical depth is needed in order to interpreted the lines correctly. &#160; In this talk I want to present our results of the class I source Elias29 as part of the FAUST (fifty au study of the chemistry in the disk/envelope system of solar-like protostars) collaboration. The goal of FAUST is to quantify the chemical composition of the envelope/disk system of solar-lie class 0 and I protostars. With the high spatial resolution of 50 au in band 3 and band 6 ALMA data we can spatially resolve the envelope and the disk on this source and calculate the dust properties of the two components.

Protostar

Envelope (radar)

10.5194/epsc2020-1102

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First spatially resolved Na i and He i transitions towards a massive young stellar object. Finding new tracers for the gaseous star/disc interface

Monthly Notices of the Royal Astronomical Society Letters (2022)

E. Koumpia M. Koutoulaki W-J de Wit R. D. Oudmaijer A. J. Frost

With steady observational advances, the formation of massive stars is being understood in more detail. Numerical models are converging on a scenario where accretion discs play a key role. Direct observational evidence of such discs at a few au scales is scarce, due to the rarity of such objects and the observational challenges, including the lack of adequate diagnostic lines in the near-IR. We present the analysis of K-band spectro-interferometric observations toward the Massive Young Stellar Object IRAS 13481-6124, which is known to host an accreting dusty disc. Using GRAVITY on the VLTI, we trace the crucial au-scales of the warm inner interface between the star and the accretion dusty disc. We detect and spatially resolve the Na I doublet and He I transitions towards an object of this class for the first time. The new observations in combination with our geometric models allowed us to probe the smallest au-scales of accretion/ejection around an MYSO. We find that Na I originates in the disc at smaller radii than the dust disc and is more compact than any of the other spatially resolved diagnostics (Br$\gamma$, He I, and CO). Our findings suggest that Na I can be a new powerful diagnostic line in tracing the warm star/disc accreting interface of forming (massive) stars, while the similarities between He I and Br$\gamma$ point towards an accretion/ejection origin of He I

Young stellar object

Compact star

10.1093/mnrasl/slac151

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Citations (1)

Unveiling accretion in the massive young stellar object G033.3891. Spatial and kinematic constraints from the CO bandhead emission

Astronomy and Astrophysics (2024)

E. Koumpia Dongsheng Sun M. Koutoulaki John D. Ilee W. J. de Wit

Context . The inner parts of the hot discs surrounding massive young stellar objects (MYSOs) are still barely explored due to observational limitations in terms of angular resolution, scarcity of diagnostic lines, and the embedded and rare nature of these targets. Aims . We present the first K -band spectro-interferometric observations towards the MYSO G033.3891, which based on former kinematic evidence via the CO bandhead emission is known to host an accreting disc. Methods . Using the high spectral resolution mode (R∼4000) of the GRAVITY/VLTI, we spatially resolved the emission of the inner dusty disc and the crucial gaseous interface between the star and the dusty disc. Using detailed modelling on the K -band dust continuum and tracers known to be associated with the ionised and molecular gaseous interface (Brγ, CO), we report on the smallest scales of accretion and ejection. Results . The new observations in combination with our geometric and kinematic models employed to fit former high spectral resolution observations on the source (R∼30 000; CRIRES/VLTI) allowed us to constrain the size of the inner gaseous disc both spatially and kinematically via the CO overtone emission at only 2 au. Our models reveal that both Brγ and CO emissions are located well within the dust sublimation radius (5 au) as traced by the hot 2.2 µm dust continuum. Conclusions . Our paper provides the first case study where the tiniest scales of gaseous accretion around the MYSO G033.3891 are probed both kinematically and spatially via the CO bandhead emission. This analysis of G033.3891 stands as only the second instance of such an investigation within MYSOs, underscoring the gradual accumulation of knowledge regarding how massive young stars gain their mass while further solidifying the disc nature of accretion at the smallest scales of MYSOs.

Young stellar object

Accretion disc

10.1051/0004-6361/202449641

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Spatially Resolving the Inner Gaseous Disc of the Herbig Star 51 Oph through its CO Ro-vibration Emission

HAL (Le Centre pour la Communication Scientifique Directe) (2019)

R. Abuter M. Accardo T. Adler A. Amorim Narsireddy Anugu

Near-infrared interferometry gives us the opportunity to spatially resolve the circumstellar environment of young stars at sub-astronomical-unit (au) scales, which a standalone telescope could not reach. In particular, the sensitivity of GRAVITY on the VLTI allows us to spatially resolve the CO overtone emission at 2.3 microns. In this article, we present a new method of using the model of the CO spectrum to reconstruct the differential phase signal and extract the geometry and size of the emitting region.

Star (game theory)

Herbig Ae/Be star

10.18727/0722-6691/5174

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