Young Massive Clusters as probes of stellar evolution
Ben Davies
备注：
8 pages, 3 figures. Review article to appear in the proceedings of "Hot and Cool: bridging the gaps in massive star evolution" - updated reference list
Young Massive Clusters (YMCs) represent ideal testbeds in which to study massive stellar evolution as they contain large, coeval, chemically homogeneous, samples of massive stars. By studying YMCs with a range of ages (and hence turn-off masses), we can investigate the post main-sequence evolution of massive stars as a function of initial mass. Recent discoveries of YMCs over a range of ages within our own Galaxy - where we can successfully resolve individual stars - offers the unprecedented opportunity to test our ideas of massive stellar evolution. Here, I review some of the recent works in this field, and describe how we can use YMCs to investigate several topics, including (a) the evolutionary state of H-rich Wolf-Rayet stars; (b) the influence of binarity on stellar evolution in dense clusters; and (c) Red Supergiants and the post-supernova remnants they leave behind.
This short review examines the most recent observational results obtained for jets driven by high-mass young stellar objects (HMYSOs). Reviewed data range from near-infrared to radio wavelengths, with particular emphasis on the IR regime, and are presented along with perspectives for future observations achievable with newly available or forthcoming facilities.
I present the latest results from our group about the multiple stellar populations in the old Milky Way globular clusters (GCs) and in the young systems both in the Magellanic Clouds and in the Milky Way. For the ancient GCs in our Galaxy I summarize the chemical properties of the stellar populations as observed on the chromosome map. Both Type I and Type II GCs are discussed. For the youngest clusters I will briefly report our latest spectroscopic analysis on the Large Magellanic Cloud cluster NGC1818 and the Galactic open cluster NGC6705 (M11), which supports the co-existence of stellar popu…
An observational review is provided of the properties of accretion disks around young stars. It concerns the primordial disks of intermediate- and high-mass young stellar objects in embedded and optically revealed phases. The properties were derived from spatially resolved observations and therefore predominantly obtained with interferometric means, either in the radio/(sub)millimeter or in the optical/infrared wavelength regions. We make summaries and comparisons of the physical properties, kinematics, and dynamics of these circumstellar structures and delineate trends where possible. Amongst…
We present HK spectra of three sources located in the N66 region of the Small Magellanic Cloud. The sources display prominent stellar Br Gamma and extended H2 emission, and exhibit infrared excesses at lambda > 2 micron. Based on their spectral features, and photometric spectral energy distributions, we suggest that these sources are massive young stellar objects (mYSOs). The findings are interpreted as evidence of on-going high mass star formation in N66.
We investigate the intrinsic stellar populations (estimated total numbers of OB and pre-main-sequence stars down to 0.1 Mo) that are present in 17 massive star-forming regions (MSFRs) surveyed by the MYStIX project. The study is based on the catalog of >31,000 MYStIX Probable Complex Members with both disk-bearing and disk-free populations, compensating for extinction, nebulosity, and crowding effects. Correction for observational sensitivities is made using the X-ray Luminosity Function (XLF) and the near-infrared Initial Mass Function (IMF)--a correction that is often not made by infrared su…
We present the results of a 40 ks XMM-Newton observation centered on the variable star V1818 Ori. Using a combination of the XMM-Newton and AllWISE catalog data, we identify a group of about 31 young stellar objects around V1818 Ori. This group is coincident with the eastern edge of the dust ring surrounding Kappa Ori. Previously, we concluded that the young stellar objects on the western side of ring were formed in an episode of star formation that started 3-5 Myr ago, and are at a distance similar to that of kappa Ori (250-280 pc) and in the foreground to the Orion A cloud. Here we use the X…
We present results of an infrared study of the molecular cloud Lynds 1340, forming three groups of low and intermediate-mass stars. Our goals are to identify and characterise the young stellar population of the cloud, study the relationships between the properties of the cloud and the emergent stellar groups, and integrate L1340 into the picture of the star-forming activity of our Galactic environment. We selected candidate young stellar objects from the Spitzer and WISE data bases using various published color criteria, and classified them based on the slope of the spectral energy distributio…
In this letter we present evidence of coherent outward motion of a sample of young stars ($t<$30 Myr) in the Perseus Arm, whose apparent origin is located in the vicinity of the W3/W4/W5 complex. Using astrometric and photometric data from the Gaia DR2 catalog of an 8$^\circ$ radius field centered near W4, we selected a sample of young, intermediate to high-mass star candidates. The sample is limited to sources with parallax uncertainties below 20% and Bayesian distance estimates within 1800 and 3100 pc. The selection includes embedded stellar populations as well as young open clusters. Projec…
We report the discovery of a new young stellar cluster in the outer Galaxy located at the position of an IRAS PSC source that has been previously mis-identified as an external galaxy. The cluster is seen in our near-infrared imaging towards IRAS 04186+5143 and in archive Spitzer images confirming the young stellar nature of the sources detected. There is also evidence of sub-clustering seen in the spatial distributions of young stars and of gas and dust. Near- and mid-infrared photometry indicates that the stars exhibit colours compatible with reddening by interstellar and circumstellar dust a…
Linking Young Stellar Object Morphology to Evolutionary Stages with Self-Organizing Maps
Universität Wien（维也纳大学）；Natural History Museum Vienna（维也纳自然历史博物馆）；Université de Genève（日内瓦大学）；Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Research Network (HUN-REN)（孔科利天文台，匈牙利研究网络（HUN-REN）地球与天文学研究中心）；CSFK, MTA Centre of Excellence（MTA卓越中心天文研究所）；Department of Experimental Physics, Institute of Physics, University of Szeged（塞格德大学物理学院实验物理系）；HITS gGmbH（海德堡理论研究所）
The recent discovery of double main sequences in the young, massive star cluster NGC 1856 has caught significant attention. The observations can be explained by invoking two stellar generations with different ages and metallicities or by a single generation of stars composed of two populations characterized by different rotation rates. We analyzed the number ratios of stars belonging to both main-sequence components in NGC 1856 as a function of radius. We found that their number ratios remain approximately unchanged from the cluster's central region to its periphery, indicating that both compo…
Star formation is a hierarchical process, forming young stellar structures of star clusters, associations, and complexes over a wide scale range. The star-forming complex in the bar region of the Large Magellanic Cloud is investigated with upper main-sequence stars observed by the VISTA Survey of the Magellanic Clouds. The upper main-sequence stars exhibit highly non-uniform distributions. Young stellar structures inside the complex are identified from the stellar density map as density enhancements of different significance levels. We find that these structures are hierarchically organized su…
The pace and pattern of star formation leading to rich young stellar clusters is quite uncertain. In this context, we analyze the spatial distribution of ages within 19 young (median t<3 Myr on the Siess et al. (2000) timescale), morphologically simple, isolated, and relatively rich stellar clusters. Our analysis is based on young stellar object samples from the MYStIX and SFiNCs surveys, and a new estimator of pre-main sequence (PMS) stellar ages, AgeJX, derived from X-ray and near-infrared photometric data. Median cluster ages are computed within four annular subregions of the clusters. We c…
The Trifid Nebula is a young, nearby star-forming region where star formation is proposed to have been triggered by cloud-cloud collision (CCC), based on observations of molecular clouds. It offers a unique opportunity to test whether the CCC hypothesis is supported by the spatial distribution and star formation chronology of young stars. We present the first study of the optically visible pre-main sequence (PMS) population of the region using riH$α$ imaging and Gaia astrometry. Combined with an analysis of young stellar objects (YSOs) using infrared imaging, we capture the spatial distributio…
A high number of embedded clusters is found in the Galaxy. Depending on the formation scenario, most of them can evolve to unbounded groups that are dissolved within a few tens of Myr. A systematic study of young stellar clusters showing distinct characteristics provide interesting information on the evolutionary phases during the pre-main sequence. In order to identify and to understand these phases we performed a comparative study of 21 young stellar clusters. Near-infrared data from 2MASS were used to determine the structural and fundamental parameters based on surface stellar density maps,…
Young stellar associations hold a star formation record that can persist for millions of years, revealing the progression of star formation long after the dispersal of the natal cloud. To identify nearby young stellar populations that trace this progression, we have designed a comprehensive framework for the identification of young stars, and use it to identify $\sim$3$\times 10^4$ candidate young stars within a distance of 333 pc using Gaia DR2. Applying the HDBSCAN clustering algorithm to this sample, we identify 27 top-level groups, nearly half of which have little to no presence in previou…
Multiple stellar populations (MPs) representing star-to-star light-element abundance variations are common in nearly all ancient Galactic globular clusters. Here we provide the strongest evidence yet that the populous, ~ 1.7 Gyr-old Large Magellanic Cloud cluster NGC 2173 also exhibits light-element abundance variations. Thus, our results suggest that NGC 2173 is the youngest cluster for which MPs have been confirmed to date. Our conclusion is based on the distinct bifurcation at the tip of its red-giant branch in high-quality color--magnitude diagrams generated from Hubble Space Telescope ima…
We report the results of VERA multi-epoch VLBI 22 GHz water maser observations of S255IR-SMA1, a massive young stellar object located in the S255 star forming region. By annual parallax the source distance was measured as D = 1.78 +-0.12 kpc and the source systemic motion was (u alpha cos d, u d) = (-0.13 +- 0.20, -0.06 +- 0.27) mas yr-1. Masers appear to trace a U-shaped bow shock whose morphology and proper motions are well reproduced by a jet-driven outflow model with a jet radius of about 6 AU. The maser data, in the context of other works in the literature, reveal ejections from S255IR-SM…
Young massive stars influence their surroundings from local to galactic scales, but the observational challenges associated with their distance and embedded nature has, until the recent decade, made high-resolution studies of these objects difficult. In particular, comparative analyses of massive young stellar object (MYSO) discs are currently lacking and our understanding of their evolution is limited. Here, we combine the results of two studies with the aim to attribute geometrical features to an evolutionary sequence for a sample of seven MYSOs. The time evolution is based on a near-IR spec…
Line-of-sight extinction estimates to well-studied young T Tauri and Herbig Ae/Be stars are based on many different measurements and analysis methods. This has resulted in wide scatter among the published $A_V$ values for the same star. In this work, we discuss the challenges in measuring extinction to actively accreting and especially outbursting young stellar objects (YSOs). We then explore a method not previously applied to young stars utilizing diffuse interstellar bands (DIBs). In early-type stars, narrow correlations exist between DIB equivalent widths and the column density of interstel…
We analyze the masses and spatial distributions of fourteen young stellar groups in Taurus, Lupus3, ChaI, and IC348. These nearby groups, which typically contain 20 to 40 members, have membership catalogs complete to ~0.02 M_sun, and are sufficiently young that their locations should be similar to where they formed. These groups show five properties seen in clusters having many more stars and much greater surface density of stars: (1) a broad range of masses, (2) a concentration of the most massive star towards the centre of the group, (3) an association of the most massive star with a high su…
In recent works, through observations of molecular lines, we found that the supernova remnant (SNR) G18.8+0.3 is interacting with a molecular cloud towards its southern edge. Also it has been proven the presence of several neighboring HII regions very likely located at the same distance as the remnant. The presence of dense molecular gas and the existence of shock fronts generated by the SNR and HII regions make this region an interesting scenario to study the population of young stellar objects. Thus, using the most modern colour criteria applied to the emission in the mid-infrared bands obta…
Young field stars are hardly distinguishable from older ones because their space motion rapidly mixes them with the stellar population of the Galactic plane. Nevertheless, a careful target selection allows for young stars to be spotted throughout the sky. We aim to identify additional sources associated with the four young comoving stars that we discovered towards the CO Cepheus void and to provide a comprehensive view of the Cepheus association. Based on multivariate analysis methods, we have built an extended sample of 193 young star candidates, which are the optical and infrared counterpart…
We analyze age distributions of two nearby rich stellar clusters, the NGC 2024 (Flame Nebula) and Orion Nebula Cluster (ONC) in the Orion molecular cloud complex. Our analysis is based on samples from the MYStIX survey and a new estimator of pre-main sequence (PMS) stellar ages, AgeJX, derived from X-ray and near-infrared photometric data. To overcome the problem of uncertain individual ages and large spreads of age distributions for entire clusters, we compute median ages and their confidence intervals of stellar samples within annular subregions of the clusters. We find core-halo age gradien…
Context. The lack of knowledge of photospheric parameters and the level of chromospheric activity in young low-mass pre-main sequence stars introduces uncertainties when measuring mass accretion rates in accreting (Class II) Young Stellar Objects. A detailed investigation of the effect of chromospheric emission on the estimates of mass accretion rate in young low-mass stars is still missing. This can be undertaken using samples of young diskless (Class III) K and M-type stars. Aims. Our goal is to measure the chromospheric activity of Class III pre main sequence stars to determine its effect o…
Accretion disks are one of the key ingredients of the star formation process. They redistribute angular momentum and, in the case of high-mass stars (M > 8Msun), disks would relieve the radiation pressure on the accreting material, in particular in the equatorial direction, by beaming the radiation through the poles of the system and this would allow the accretion to proceed onto the central protostar (e.g., Tan et al. 2014 for a review on massive star formation). In fact, in recent years, all high-mass star-forming theories appear to converge to a disk-mediated accretion scenario (e.g., Krumh…
This article represents a short review of the variability characteristics of young stellar objects. Variability is a key property of young stars. Two major origins may be distinguished: a scaled-up version of the magnetic activity seen on main-sequence stars and various processes related to circumstellar disks, accretion and outflows.
We conducted an infrared search for faint companions around 351 young stellar objects in the rho Ophiucus molecular cloud and the Serpens molecular cloud. Nine objects in the Spitzer/IRAC archival images were identified as young stellar companion candidates. They showed an intrinsic infrared excess; one object was extremely red both in the [3.6] - [4.5] color and in the [4.5] - [5.8] color, and two objects were red in the [4.5] - [5.8] color. They were as faint as 15 mag in the [3.6] band. Follow-up K-band spectroscopy revealed that three objects had deep water absorption bands, indicative of …
Stellar evolution models are a cornerstone of young star astrophysics, which necessitates that they yield accurate and reliable predictions of stellar properties. Here, I review the current performance of stellar evolution models against young astrophysical benchmarks and highlight recent progress incorporating non-standard physics, such as magnetic field and starspots, to explain observed deficiencies. While addition of these physical processes leads to improved agreement between models and observations, there are several fundamental limitations in our understanding about how these physical p…
We discuss VLTI AMBER and MIDI interferometry in addition to single-dish Subaru observations of massive young stellar objects. The observations probe linear size scales between 10 to 1000 AU for the average distance of our sources.
In this contribution we explore the new science that a Next Generation Very Large Array (ngVLA) would be able to perform on the topics of the youngest HII regions and (proto)stellar jets. Free-free continuum and radio recombination line (RRL) emission are often the only way of peering into the dense envelopes surrounding (proto)stars of all masses, and trace their initial feedback in the form of `radio jets', `hypercompact HII regions', or photoevaporating, partially-ionized flows. Properly disentangling free-free from dust emission is also mandatory in studies of protoplanetary and accretion …
As part of the project Pathways to Habitability (http://path.univie.ac.at/), we study the properties of the stellar winds of low-mass and Sun-like stars, and their influences on the atmospheres of potentially habitable planets. For this purpose, we combine mapping of stellar magnetic fields with magnetohydrodynamic wind models.
Observations of young open clusters show a bimodal distribution of stellar rotation. Sun-like stars in those clusters group into two main sub-populations of fast and slow rotators. Beyond an age of about 500 Myrs, the two populations converge towards a single peak distribution of angular velocities. I argue that this evolution of stellar rotation in open clusters results from a brief episode of enhanced angular momentum loss by strong stellar wind during the early evolution of rapidly rotating Sun-like stars
An introduction to the theory and practical aspects of infrared interferometry is given in the context of the study of massive young stellar objects. Basic interferometric concepts, as well as observable quantities and their use, are presented. Recent advancements in interferometric studies of massive young stellar objects are discussed.
I review progress towards understanding the time-scales of star and cluster formation and of the absolute ages of young stars. I focus in particular on the areas in which Francesco Palla made highly significant contributions - interpretation of the Hertzsprung-Russell diagrams of young clusters and the role of photospheric lithium as an age diagnostic.
This summary talk aims at highlighting some of the remaining open issues regarding the physics of the magnetospheric accretion/ejection process in young stellar objects (YSOs). It lists a number of questions related to YSOs magnetic fields and accretion regimes, the structure and properties of accretion shocks, the origin of multiple outflow components, and the impact of the star-disk magnetic interaction onto early angular momentum evolution.
We applied the extinction-disk-principal vectors approach to near infrared photometric data of the Taurus-Auriga region and Orion Nebula young stellar clusters. By assuming that the cluster age is represented by the median value of the age distribution we are able to derive the distribution of stellar masses. We showed that the resulting initial mass function (IMF) for these two young stellar clusters compares remarkably well and might be a robust representation of the IMF obtained by spectroscopic or photometric methods. The method also yields extinction and disk contribution for each star. T…
While searches for young stellar objects (YSOs) with the Spitzer Space Telescope focused on known molecular clouds, photometry from the Wide-field Infrared Survey Explorer (WISE) can be used to extend the search to the entire sky. As a precursor to more expansive searches, we present results for a 100 square degree region centered on the Canis Major clouds.
Magnetically active stars are the sites of efficient particle acceleration and plasma heating, processes that have been studied in detail in the solar corona. Investigation of such processes in young stellar objects is much more challenging due to various absorption processes. There is, however, evidence for violent magnetic energy release in very young stellar objects. The impact on young stellar environments (e.g., circumstellar disk heating and ionization, operation of chemical networks, photoevaporation) may be substantial. Hard X-ray devices like those carried on Simbol-X will establish a…
Recent observations have suggested that circumstellar disks may commonly form around young stellar objects. Although the formation of circumstellar disks can be a natural result of the conservation of angular momentum in the parent cloud, theoretical studies instead show disk formation to be difficult from dense molecular cores magnetized to a realistic level, owing to efficient magnetic braking that transports a large fraction of the angular momentum away from the circumstellar region. We review recent progress in the formation and early evolution of disks around young stellar objects of both…
The Tucana-Horologium association is one of the closest young stellar groups to the Sun and despite the close proximity its age is still debated in the literature. We take advantage of the state-of-the-art astrometry delivered by the third data release of the Gaia space mission combined with precise radial velocity measurements obtained from high-resolution spectroscopy to investigate the dynamical age of the association. We perform an extensive traceback analysis using a combination of different samples of cluster members, metrics to evaluate the minimum size of the association in the past an…
Gaia EDR3 offers greatly improved kinematics for nearby objects, including members of nearby young stellar moving groups (NYMGs). In this study, we aim to identify low-mass NYMG members (spectral types of M0 to mid-L) in Gaia EDR3. We calculated spatio-kinematic membership probabilities utilising a Bayesian membership probability calculation scheme developed in our previous study. We evaluated stellar youth primarily based on colour-magnitude diagram positions. Combining spatio-kinematic membership assessment and youth evaluation, we identified ~2900 low-mass NYMG candidate members including ~…
We describe our all-sky survey for >M4 candidate members to nearby, young associations from the 2MASS and WISE catalogs using bayesian inference. We report the first results, including 38 highly probable candidates showing spectroscopic signs of low-gravity (and thus youth). The latest of these objects would correspond to a 11 - 13 MJup object, around the limit of the planetary regime.
Results from BVRI photometric observations of the pre-main sequence star V1704 Cyg collected during the time period from August 2010 to December 2017 are presented. The star is located in the star-forming HII region IC 5070 and it exhibits photometric variability in all-optical passbands. After analyzing the obtained data, V1704 Cyg is classified as a classical T Tauri star.
Spectroscopic equilibrium allows us to obtain precise stellar parameters in Sun-like stars. It relies on the assumption of the iron excitation and ionization equilibrium. However, several works suggest that magnetic activity may affect chemical abundances of young active stars, calling into question the validity of this widely-used method. We have tested for the first time variations in stellar parameters and chemical abundances for the young solar twin HIP 36515 ($\sim$0.4 Gyr), along its activity cycle. This star has stellar parameters very well established in the literature and we estimated…
Observations of the spatial distributions of young stars in star-forming regions can be linked to the theory of clustered star formation using spatial statistical methods. The MYStIX project provides rich samples of young stars from the nearest high-mass star-forming regions. Maps of stellar surface density reveal diverse structure and subclustering. Young stellar clusters and subclusters are fit with isothermal spheres and ellipsoids using the Bayesian Information Criterion to estimate the number of subclusters. Clustering is also investigated using Cartwright and Whitworth's Q statistic and …
Results from the BV(RI)c photometric observations of the young stellar object V2492 Cyg collected in the period from April 2018 to September 2020 are presented. These observations are a part of our monitoring of the star that began in 2010 and continuing to date. V2492 Cyg is located in the Pelican Nebula, and its variability was explained by both accretion and extinction events. The new photometric data show that the star continues to exhibit rapid irregular variability in all bands. In the period from March 2019 to May 2020, we registered a prolonged decrease event in the light curve of V249…
We use HST observations to study the LMC's young cluster NGC1844. We estimate the fraction and the mass-ratio distribution of photometric binaries and report that the main sequence presents an intrinsic breadth which can not be explained in terms of photometric errors only, and is unlikely due to differential reddening. We attempt some interpretation of this feature, including stellar rotation, binary stars, and the presence of multiple stellar populations with different age, metallicity, helium, or C+N+O abundance. Although we exclude age, helium, and C+N+O variations to be responsible of the…
The Wide-field Infrared Survey Explorer has uncovered a population of young stellar objects in the Western Circinus molecular cloud. Images show the YSOs to be clustered into two main groups that are coincident with dark filamentary structure in the nebulosity. Analysis of photometry shows numerous Class I and II objects. The locations of several of these objects are found to correspond to known dense cores and CO outflows. Class I objects tend to be concentrated in dense aggregates, and Class II objects more evenly distributed throughout the region.
It is known that scattering of radiation by circumstellar dust can strongly change the line profiles in stellar spectra. This hampers the analysis of spectral lines originating in the emitting regions of heavily obscured young stars. To calculate the line profile of the scattered radiation, we suggest to use the approximation of remote scattering particles. This approximation assumes that the scattering dust grains are at a distance from the star that is much larger than the characteristic size of the emitting region. Using this method, we calculated the line profiles of several simple models.…
We construct a scenario where the outburst of the young-stellar-object ASASSN-15qi is an intermediate luminosity optical transient (ILOT). In this scenario a sub-Jupiter young planet was tidally destructed on to a young main-sequence star. The system is young, therefore the radius of the planet is larger than its final value, and consequently its density is smaller. The lower density allows the tidal destruction of the young Saturn-like planet on to the main-sequence star of mass $\approx 2.4~\rm{M_\odot}$, resulting in a formation of a disc and a gravitationally-powered ILOT. Unlike the case …
We present early results of our multiwavelength study of the star forming region IRAS 20050+2720. While we use X-rays and IR to classify young stellar objects, the optical data can be used to exclude foreground objects. The dataset set contains 57 class I sources, 183 class II sources and 183 X-ray sources, of which 140 are class III candidates. Within IRAS 20050+2720 four subclusters are found. Subcluster A and B are the densest regions, which contain stars of all evolutionary stages. Subcluster C is much younger than the other two. It has not formed any class III objects yet. We newly identi…
Young stars show a variety of highly energetic phenomena, from accretion and outflow processes to hot coronal plasmas confined in their outer atmosphere, all regulated by the intense stellar magnetic fields. Many aspects on each of these phenomena are debated, but, most notably, their complex mutual interaction remains obscure. In this work I report how these phenomena are simultaneously responsible for the high-energy emission from young stars, with a special focus on the expected and observed variability in the X-ray band. Investigating variations in the X-ray emission from young stars allow…
Equivalent widths and line widths of Ca II infrared triplet emission lines were measured in high-resolution optical spectra of 39 young stellar objects.We found that the equivalent widths of the emission lines decrease with stellar evolution. It has been often claimed that strong chromospheric activity is generated by a dynamo process caused by fast rotation of the photosphere. However, we found no clear correlation between the strength of the Ca II lines and the stellar rotation velocity. Instead, we found that the objects with high mass accretion rates had stronger Ca II emission lines. This…
High-precision photometry from space-based missions such as K2 and TESS enables detailed studies of young star variability. However, because space-based observing campaigns are often short (e.g., 80 days for K2), complementary long-baseline photometric surveys are critical for obtaining a complete understanding of young star variability, which can change on timescales of minutes to years. We therefore present and analyze light curves of members of the Upper Scorpius association made over 5.5 years by the ground-based Kilodegree Extremely Little Telescope (KELT), which complement the high-preci…
In our own solar system, the necessity of understanding space weather is readily evident. Fortunately for Earth, our nearest stellar neighbor is relatively quiet, exhibiting activity levels several orders of magnitude lower than young, solar-type stars. In protoplanetary systems, stellar magnetic phenomena observed are analogous to the solar case, but dramatically enhanced on all physical scales: bigger, more energetic, more frequent. While coronal mass ejections (CMEs) could play a significant role in the evolution of protoplanets, they could also affect the evolution of the central star itse…
