The circumstellar environment of HD50138 revealed by VLTI/AMBER at high angular resolution

HD50138 is a Herbig B[e] star with a circumstellar disc detected at IR and mm wavelength. Its brightness makes it a good candidate for NIR interferometry observations. We aim to resolve, spatially and spectrally, the continuum and hydrogen emission lines in the 2.12-2.47 micron region, to shed light on the immediate circumstellar environment of the star. VLTI/AMBER K-band observations provide spectra, visibilities, differential phases, and closure phases along three long baselines for the continuum, and HI emission in Br$\gamma$ and five high-n Pfund lines. By computing the pure-line visibilities, we derive the angular size of the different line-emitting regions. A simple LTE model was created to constrain the physical conditions of HI emitting region. The continuum region cannot be reproduced by a geometrical 2D elongated Gaussian fitting model. We estimate the size of the region to be 1 au. We find the Br$\gamma$ and Pfund lines come from a more compact region of size 0.4 au. The Br$\gamma$ line exhibits an S-shaped differential phase, indicative of rotation. The continuum and Br$\gamma$ line closure phase show offsets of $\sim$-25$\pm$5 $^o$ and 20$\pm$10$^o$, respectively. This is evidence of an asymmetry in their origin, but with opposing directions. We find that we cannot converge on constraints for the HI physical parameters without a more detailed model. Our analysis reveals that HD50138 hosts a complex circumstellar environment. Its continuum emission cannot be reproduced by a simple disc brightness distribution. Similarly, several components must be evoked to reproduce the interferometric observables within the Br$\gamma$, line. Combining the spectroscopic and interferometric data of the Br$\gamma$ and Pfund lines favours an origin in a wind region with a large opening angle. Finally, our results point to an evolved source.Comment: accepted for publication in A&

Exploring the dimming event of RW Aur A through multi-epoch VLT/X-Shooter spectroscopy

RW Aur A is a CTTS that has suddenly undergone three major dimming events since 2010. We aim to understand the dimming properties, examine accretion variability, and derive the physical properties of the inner disc traced by the CO ro-vibrational emission at NIR wavelengths (2.3 mic). We compared two epochs of X-Shooter observations, during and after the dimming. We modelled the rarely detected CO bandhead emission in both epochs to examine whether the inner disc properties had changed. The SED was used to derive the extinction properties of the dimmed spectrum and compare the infrared excess between the two epochs. Lines tracing accretion were used to derive the mass accretion rate in both states. The CO originates from a region with physical properties of T=3000 K, N$_{CO}$=1x10$^{21}$ cm$^{-2}$ and vsini=113 km/s. The extinction properties of the dimming layer were derived with the effective optical depth ranging from teff 2.5-1.5 from the UV to the NIR. The inferred mass accretion rate Macc is $1.5x 10^{-8}$ Msun/yr and $\sim 2x 10^{-8}$ Msun/yr after and during the dimming respectively. By fitting the SED, additional emission is observed in the IR during the dimming event from dust grains with temperatures of 500-700K. The physical conditions traced by the CO are similar for both epochs, indicating that the inner gaseous disc properties do not change during the dimming events. The extinction curve is flatter than that of the ISM, and large grains of a few hundred microns are thus required. When we correct for the observed extinction, Macc is constant in the two epochs, suggesting that the accretion is stable and therefore does not cause the dimming. The additional hot emission in the NIR is located at about 0.5 au from the star. The dimming events could be due to a dust-laden wind, a severe puffing-up of the inner rim, or a perturbation caused by the recent star-disc encounter.Comment: Accepted by Astronomy & Astrophysic

Mirror, mirror on the outflow cavity wall: Near-infrared CO overtone disc emission of the high-mass YSO IRAS 11101-5829

Aims. The inner regions of high-mass protostars are often invisible in the near-infrared, obscured by thick envelopes and discs. We aim to investigate the inner gaseous disc of IRAS 11101-5829 through scattered light from the outflow cavity walls. Methods. We observed the immediate environment of the high-mass young stellar object IRAS 11101-5829 and the closest knots of its jet, HH135-136, with the integral field unit VLT/SINFONI. We also retrieved archival data from the high-resolution long-slit spectrograph VLT/X-shooter. We analysed imaging and spectroscopic observations to discern the nature of the near-infrared CO emission. Results. We detect the first three bandheads of the υ = 2−0 CO vibrational emission for the first time in this object. It is coincident with continuum and Brγ emission and extends up to ~10 000 au to the north-east and ~10 000 au to the south-west. The line profiles have been modelled as a Keplerian rotating disc assuming a single ring in local thermodynamic equilibrium. The model output gives a temperature of ~3000 K, a CO column density of ~1 × 1022 cm−2, and a projected Keplerian velocity vK sin idisc ~ 25 km s−1, which is consistent with previous modelling in other high-mass protostars. In particular, the low value of vK sin idisc suggests that the disc is observed almost face-on, whereas the well-constrained geometry of the jet imposes that the disc must be close to edge-on. This apparent discrepancy is interpreted as the CO seen reflected in the mirror of the outflow cavity wall. Conclusions. From both jet geometry and disc modelling, we conclude that all the CO emission is seen through reflection by the cavity walls and not directly. This result implies that in the case of highly embedded objects, as for many high-mass protostars, line profile modelling alone might be deceptive and the observed emission could affect the derived physical and geometrical properties; in particular the inclination of the system can be incorrectly interpreted

The sharpest view on the high-mass star-forming region S255IR. Near-InfraRed Adaptive Optics Imaging on the Outbursting Source NIRS3

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, but observations of these events have only been reported towards a handful of massive protostars. We aim to investigate the outburst event from the high-mass star-forming region S255IR where recently the protostar NIRS3 underwent an accretion outburst. We follow the evolution of this source both in photometry and morphology of its surroundings. Methods: We perform near-infrared adaptive optics observations on the S255IR central region using the Large Binocular Telescope in the K$_{\rm s}$ broad-band and the H$_2$ and Br$\gamma$ narrow-band filters with an angular resolution of \sim0\farcs06, close to the diffraction limit. We discover a new near-infrared knot north-east from 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 measure a mean tangential velocity for this knot of $450\pm50\,\mathrm{km\,s^{-1}}$. We analyse the continuum-subtracted images from H$_2$ which traces jet shocked emission, and Br$\gamma$ which traces scattered light from a combination of accretion activity and UV radiation from the central massive protostar. We observe a significant decrease in flux at the location of NIRS3, with K=13.48\,mag being the absolute minimum in the historic series. Our observations strongly suggest a scenario where the episodic accretion is followed by an episodic ejection response in the near-infrared, as it was seen in the earlier radio follow-up. The 30 years of $\sim2\,\mu{\rm m}$ photometry suggests that NIRS3 might have undergone another outburst in the late 1980s, being the first massive protostar with such evidence observed in the near-infrared.Comment: Accepted for publication in Astronomy and Astrophysics. 10 pages, 8 figure

PENELLOPE: The ESO data legacy program to complement the Hubble UV Legacy Library of Young Stars (ULLYSES)

The evolution of young stars and disks is driven by the interplay of several processes, notably the accretion and ejection of material. These processes, critical to correctly describe the conditions of planet formation, are best probed spectroscopically. Between 2020 and 2022, about 500orbits of the Hubble Space Telescope (HST) are being devoted in to the ULLYSES public survey of about 70 low-mass (M⋆ ≤ 2 M⊙) young (age < 10 Myr) stars at UV wavelengths. Here, we present the PENELLOPE Large Program carried out with the ESO Very Large Telescope (VLT) with the aim of acquiring, contemporaneously to the HST, optical ESPRESSO/UVES high-resolution spectra for the purpose of investigating the kinematics of the emitting gas, along with UV-to-NIR X-shooter medium-resolution flux-calibrated spectra to provide the fundamental parameters that HST data alone cannot provide, such as extinction and stellar properties. The data obtained by PENELLOPE have no proprietary time and the fully reduced spectra are being made available to the whole community. Here, we describe the data and the first scientific analysis of the accretion properties for the sample of 13 targets located in the Orion OB1 association and in the σ-Orionis cluster, observed in November–December 2020. We find that the accretion rates are in line with those observed previously in similarly young star-forming regions, with a variability on a timescale of days (≲3). The comparison of the fits to the continuum excess emission obtained with a slab model on the X-shooter spectra and the HST/STIS spectra shows a shortcoming in the X-shooter estimates of ≲10%, which is well within the assumed uncertainty. Its origin can be either due to an erroneous UV extinction curve or to the simplicity of the modeling and, thus, this question will form the basis of the investigation undertaken over the course of the PENELLOPE program. The combined ULLYSES and PENELLOPE data will be key in attaining a better understanding of the accretion and ejection mechanisms in young stars

The circumstellar environment of HD 50138 revealed by VLTI/AMBER at high angular resolution

Context. HD 50138 is a Herbig B[e] star with a circumstellar disc detected at infrared and millimeter wavelength. Its brightness makes it a good candidate for near-infrared interferometry observations. Aims. We aim to resolve, spatially and spectrally, the continuum and hydrogen emission lines in the 2.12–2.47 micron region, to shed light on the immediate circumstellar environment of the star. Methods. VLTI/AMBER K-band observations provide spectra, visibilities, differential phases, and closure phases along three long baselines for the continuum, and H I emission in Brγ and five high-n Pfund lines. By computing the pure line visibilities, we derive the angular size of the different line-emitting regions. A simple local thermodynamic equilibrium (LTE) model was created to constrain the physical conditions of H I emitting region. Results. The continuum region cannot be reproduced by a geometrical two-dimensional (2D) elongated Gaussian fitting model. We estimate the size of the region to be 1 au. We find the detected hydrogen lines (Brγ and Pfund lines) come from a more compact region of size 0.4 au. The Brγ line exhibits an S-shaped differential phase, indicative of rotation. The continuum and Brγ line closure phases show offsets of ~ −25 ± 5° and 20 ± 10° respectively. This is evidence of an asymmetry in their origin, but with opposing directions. We find that we cannot converge on constraints for the HI physical parameters without a more detailed model. Conclusions. Our analysis reveals that HD 50138 hosts a complex circumstellar environment. Its continuum emission cannot be reproduced by a simple disc brightness distribution. Similarly, several components must be evoked to reproduce the interferometric observables within the Brγ line. Combining the spectroscopic and interferometric data of the Brγ and Pfund lines favours an origin in a wind region with a large opening angle. Finally, although we cannot exclude the possibility that HD 50138 is a young star our results point to an evolved source.European Commission Horizon 2020European Research CouncilIrish Research CouncilScience Foundation IrelandESO Fellowship Programm

The circumstellar environment of HD 50138 revealed by VLTI/AMBER at high angular resolution

Context. HD 50138 is a Herbig B[e] star with a circumstellar disc detected at infrared and millimeter wavelength. Its brightness makes it a good candidate for near-infrared interferometry observations. Aims. We aim to resolve, spatially and spectrally, the continuum and hydrogen emission lines in the 2.12–2.47 micron region, to shed light on the immediate circumstellar environment of the star. Methods. VLTI/AMBER K-band observations provide spectra, visibilities, differential phases, and closure phases along three long baselines for the continuum, and H I emission in Brγ and five high-n Pfund lines. By computing the pure line visibilities, we derive the angular size of the different line-emitting regions. A simple local thermodynamic equilibrium (LTE) model was created to constrain the physical conditions of H I emitting region. Results. The continuum region cannot be reproduced by a geometrical two-dimensional (2D) elongated Gaussian fitting model. We estimate the size of the region to be 1 au. We find the detected hydrogen lines (Brγ and Pfund lines) come from a more compact region of size 0.4 au. The Brγ line exhibits an S-shaped differential phase, indicative of rotation. The continuum and Brγ line closure phases show offsets of ~ −25 ± 5° and 20 ± 10° respectively. This is evidence of an asymmetry in their origin, but with opposing directions. We find that we cannot converge on constraints for the HI physical parameters without a more detailed model. Conclusions. Our analysis reveals that HD 50138 hosts a complex circumstellar environment. Its continuum emission cannot be reproduced by a simple disc brightness distribution. Similarly, several components must be evoked to reproduce the interferometric observables within the Brγ line. Combining the spectroscopic and interferometric data of the Brγ and Pfund lines favours an origin in a wind region with a large opening angle. Finally, although we cannot exclude the possibility that HD 50138 is a young star our results point to an evolved source.European Commission Horizon 2020European Research CouncilIrish Research CouncilScience Foundation IrelandESO Fellowship Programm

Detection of KRAS G12/G13 Mutations in Cell Free-DNA by Droplet Digital PCR, Offers Prognostic Information for Patients with Advanced Non-Small Cell Lung Cancer

KRAS mutations are found in approximately one third of non-small cell lung cancer (NSCLC) patients. In this study, we aim to investigate whether KRAS G12/G13 mutant allele fraction (MAF) in cell-free DNA (cfDNA) can provide meaningful prognostic information in NSCLC. Multiplex droplet-digital PCR was used to quantitatively assess KRAS G12/G13 MAF in cfDNA from 114 pre-treated advanced disease NSCLC patients. In 14 patients, changes in KRAS G12/G13 MAF were longitudinally monitored during treatment. Plasma KRAS G12/G13 status was associated with poor patients’ outcome in terms of progression-free survival (PFS) (p < 0.001) and overall survival (OS) (p < 0.001). In multivariate analysis, the detection of plasma KRAS mutations was an independent predictor of adverse PFS (HR = 3.12; p < 0.001) and OS (HR = 2.53; p = 0.002). KRAS G12/G13 MAF at first treatment evaluation (T1) was higher (p = 0.013) among patients experiencing progressive disease compared to those with disease control, and increased KRAS MAF at T1 was associated (p = 0.005) with shorter PFS. On the contrary, no association was observed between tissue KRAS mutation status and patients’ prognosis. Our results show that ddPCR-based detection of KRAS G12/G13 mutations in plasma could serve as an independent biomarker of unfavorable prognosis in NSCLC patients. Changes in KRAS MAF can provide valuable information for monitoring patient outcome during treatment.KRAS mutations are found in approximately one third of non-small cell lung cancer (NSCLC) patients. In this study, we aim to investigate whether KRAS G12/G13 mutant allele fraction (MAF) in cell-free DNA (cfDNA) can provide meaningful prognostic information in NSCLC. Multiplex droplet-digital PCR was used to quantitatively assess KRAS G12/G13 MAF in cfDNA from 114 pre-treated advanced disease NSCLC patients. In 14 patients, changes in KRAS G12/G13 MAF were longitudinally monitored during treatment. Plasma KRAS G12/G13 status was associated with poor patients’ outcome in terms of progression-free survival (PFS) (p < 0.001) and overall survival (OS) (p < 0.001). In multivariate analysis, the detection of plasma KRAS mutations was an independent predictor of adverse PFS (HR = 3.12; p < 0.001) and OS (HR = 2.53; p = 0.002). KRAS G12/G13 MAF at first treatment evaluation (T1) was higher (p = 0.013) among patients experiencing progressive disease compared to those with disease control, and increased KRAS MAF at T1 was associated (p = 0.005) with shorter PFS. On the contrary, no association was observed between tissue KRAS mutation status and patients’ prognosis. Our results show that ddPCR-based detection of KRAS G12/G13 mutations in plasma could serve as an independent biomarker of unfavorable prognosis in NSCLC patients. Changes in KRAS MAF can provide valuable information for monitoring patient outcome during treatment

Detection of KRAS G12/G13 Mutations in Cell Free-DNA by Droplet Digital PCR, Offers Prognostic Information for Patients with Advanced Non-Small Cell Lung Cancer

KRAS mutations are found in approximately one third of non-small cell lung cancer (NSCLC) patients. In this study, we aim to investigate whether KRAS G12/G13 mutant allele fraction (MAF) in cell-free DNA (cfDNA) can provide meaningful prognostic information in NSCLC. Multiplex droplet-digital PCR was used to quantitatively assess KRAS G12/G13 MAF in cfDNA from 114 pre-treated advanced disease NSCLC patients. In 14 patients, changes in KRAS G12/G13 MAF were longitudinally monitored during treatment. Plasma KRAS G12/G13 status was associated with poor patients&rsquo; outcome in terms of progression-free survival (PFS) (p &lt; 0.001) and overall survival (OS) (p &lt; 0.001). In multivariate analysis, the detection of plasma KRAS mutations was an independent predictor of adverse PFS (HR = 3.12; p &lt; 0.001) and OS (HR = 2.53; p = 0.002). KRAS G12/G13 MAF at first treatment evaluation (T1) was higher (p = 0.013) among patients experiencing progressive disease compared to those with disease control, and increased KRAS MAF at T1 was associated (p = 0.005) with shorter PFS. On the contrary, no association was observed between tissue KRAS mutation status and patients&rsquo; prognosis. Our results show that ddPCR-based detection of KRAS G12/G13 mutations in plasma could serve as an independent biomarker of unfavorable prognosis in NSCLC patients. Changes in KRAS MAF can provide valuable information for monitoring patient outcome during treatment