Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userOn the Formation of Runaway Stars BN and x in the Orion Nebula Cluster
208
0
0.0
(
0
)
Authors
Juan P. Farias Dept. of Space
Ask ChatGPT about the research
No Arabic abstract
We explore scenarios for the dynamical ejection of stars BN and x from source I in the Kleinmann-Low nebula of the Orion Nebula Cluster (ONC), which is important for being the closest region of massive star formation. This ejection would cause source I to become a close binary or a merger product of two stars. We thus consider binary-binary encounters as the mechanism to produce this event. By running a large suite of $N$-body simulations, we find that it is nearly impossible to match the observations when using the commonly adopted masses for the participants, especially a source I mass of $7:{rm{M}}_odot$. The only way to recreate the event is if source I is more massive, i.e., $sim20:{rm{M}}_odot$. However, even in this case, the likelihood of reproducing the observed system is low. We discuss the implications of these results for understanding this important star-forming region.
rate research
Read More
We have performed Monte Carlo simulations of the trajectories of several runaway stars using their parallaxes and proper motions from the Gaia EDR3 catalogue. We have confirmed the hypothesis that the stars AE Aur and $mu$Col are a product of the multiple system breakup $sim$2.5 Myr ago and the Orion Trapezium may be the parent cluster for this pair of stars. We show that the data from the Gaia EDR3 catalogue for the star $iota$Ori, mainly the parallax, do not allow us to talk about the breakup of the multiple system of AE Aur, $mu$Col, and $iota$Ori. The existence of close pair encounters between the stars HD 30112 and HD 43112 $sim$1 Myr ago has been confirmed. Close triple encounters confirm the hypothesis that the stars HD 30112 and HD 43112 escaped from the parent cluster Col 69. We show that the stars HIP 28133 and TYC 5368-1541-1 have a nonzero probability of escape from the region within 10 pc of the center of the Orion Trapezium cluster and a fairly high probability (about 8%) that they were both at distances less than 20 pc from the center of the Orion Trapezium $sim$2.5 Myr ago. It has been established for the first time that the stars Gaia EDR3 3021115184676332288 and Gaia EDR3 2983790269606043648 have a probability of about 0.5% that they broke up as a binary system $sim$1.1 Myr ago. The star Gaia EDR3 3021115184676332288 has a probability of about 16% that it escaped from the region within 10 pc of the center of the Orion Trapezium cluster $sim$1 Myr ago.
The proper motions of the three stars ejected from Orions OMC1 cloud core are combined with the requirement that their center of mass is gravitationally bound to OMC1 to show that radio source I (Src I) is likely to have a mass around 15 Solar masses consistent with recent measurements. Src I, the star with the smallest proper motion, is suspected to be either an AU-scale binary or a protostellar merger remnant produced by a dynamic interaction ~550 years ago. Near-infrared 2.2 um images spanning ~21 years confirm the ~55 km/s motion of `source x (Src x) away from the site of stellar ejection and point of origin of the explosive OMC1 protostellar outflow. The radial velocities and masses of the Becklin-Neugebauer (BN) object and Src I constrain the radial velocity of Src x to be V_{LSR} = -28 +/-10 km/s . Several high proper-motion radio sources near BN, including Zapata 11 ([ZRK2004] 11) and a diffuse source near IRc 23, may trace a slow bipolar outflow from BN. The massive disk around Src I is likely the surviving portion of a disk that existed prior to the stellar ejection. Though highly perturbed, shocked, and re-oriented by the N-body interaction, enough time has elapsed to allow the disk to relax with its spin axis roughly orthogonal to the proper motion.
(Abridged) Context: Both X-ray and radio observations offer insight into the high-energy processes of young stellar objects (YSOs). The observed thermal X-ray emission can be accompanied by both thermal and nonthermal radio emission. Due to variability, simultaneous X-ray and radio observations are a priori required, but results have been inconclusive. Aims: We use archival X-ray and radio observations of the Orion Nebula Cluster (ONC) to significantly enlarge the sample size of known YSOs with both X-ray and radio detections. Methods: We study the ONC using multi-epoch non-simultaneous archival Chandra X-ray and NRAO Very Large Array (VLA) single-band radio data. The multiple epochs allow us to reduce the impact of variability by obtaining approximated quiescent fluxes. Results: We find that only a small fraction of the X-ray sources (7%) have radio counterparts, even if 60% of the radio sources have X-ray counterparts. The radio flux density is typically too low to distinguish thermal and nonthermal radio sources. Only a small fraction of the YSOs with detections in both bands are compatible with the empirical Guedel-Benz (GB) relation. Most of the sources not compatible with the GB relation are proplyds, and thus likely thermal sources, but only a fraction of the proplyds is detected in both bands, such that the role of these sources is inconclusive. Conclusions: While the radio sources appear to be globally unrelated to the X-ray sources, the X-ray dataset clearly is much more sensitive than the radio data. We find tentative evidence that known non-thermal radio sources and saturated X-ray sources are indeed close to the empirical relation, even if skewed to higher radio luminosities, as they are expected to be. Most of the sources that are clearly incompatible with the empirical relation are proplyds which could instead plausibly be thermal radio sources.
We present a deep centimeter-wavelength catalog of the Orion Nebula Cluster (ONC), based on a 30h single-pointing observation with the Karl G. Jansky Very Large Array in its high-resolution A-configuration using two 1 GHz bands centered at 4.7 GHz and 7.3 GHz. A total of 556 compact sources were detected in a map with a nominal rms noise of 3 muJy/bm, limited by complex source structure and the primary beam response. Compared to previous catalogs, our detections increase the sample of known compact radio sources in the ONC by more than a factor of seven. The new data show complex emission on a wide range of spatial scales. Following a preliminary correction for the wideband primary-beam response, we determine radio spectral indices for 170 sources whose index uncertainties are less than +/-0.5. We compare the radio to the X-ray and near-infrared point-source populations, noting similarities and differences.
We present a catalog of high-precision proper motions in the Orion Nebula Cluster (ONC), based on Treasury Program observations with the Hubble Space Telescopes (HST) ACS/WFC camera. Our catalog contains 2,454 objects in the magnitude range of $14.2<m_{rm F775W}<24.7$, thus probing the stellar masses of the ONC from $sim$0.4 $M_odot$ down to $sim$0.02 $M_odot$ over an area of $sim$550 arcmin$^2$. We provide a number of internal velocity dispersion estimates for the ONC that indicate a weak dependence on the stellar location and mass. There is good agreement with the published velocity dispersion estimates, although nearly all of them (including ours at $sigma_{v,x}=0.94$ and $sigma_{v,y}=1.25$ mas yr$^{-1}$) might be biased by the overlapping young stellar populations of Orion A. We identified 4 new ONC candidate runaways based on HST and the Gaia DR2 data, all with masses less than $sim$1 $M_odot$. The total census of known candidate runaway sources is 10 -- one of the largest samples ever found in any Milky Way open star cluster. Surprisingly, none of them has the tangential velocity exceeding 20 km s$^{-1}$. If most of them indeed originated in the ONC, it may compel re-examination of dynamical processes in very young star clusters. It appears that the mass function of the ONC is not significantly affected by the lost runaways.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
