Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userGaia 17bpi: An FU Ori Type Outburst
99
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We report on the source Gaia 17bpi and identify it as a new, ongoing FU Ori type outburst, associated with a young stellar object. The optical lightcurve from Gaia exhibited a 3.5 mag rise with the source appearing to plateau in mid/late 2018. Mid-infrared observations from NEOWISE also show a $>$3 mag rise that occurred in two stages, with the second one coincident with the optical brightening, and the first one preceding the optical brightening by $sim$1.5 years. We model the outburst as having started between October and December of 2014. This wavelength-dependent aspect of young star accretion-driven outbursts has never been documented before. Both the mid-infrared and the optical colors of the object become bluer as the outburst proceeds. Optical spectroscopic characteristics in the outburst phase include: a GK-type absorption spectrum, strong wind/outflow in e.g. Mgb, NaD, H$alpha$, KI, OI, and CaII profiles, and detection of LiI 6707 AA. The infrared spectrum in the outburst phase is similar to that of an M-type spectrum, notably exhibiting prominent $H_2O$ and $^{12}$CO (2-0) bandhead absorption in the K-band, and likely HeI wind in the Y-band. The new FU Ori source Gaia 17bpi is associated with a little-studied dark cloud in the galactic plane, located at a distance of 1.27 kpc.
rate research
Read More
Complex organic molecules (COMs), which are the seeds of prebiotic material and precursors of amino acids and sugars, form in the icy mantles of circumstellar dust grains but cannot be detected remotely unless they are heated and released to the gas phase. Around solar-mass stars, water and COMs only sublimate in the inner few au of the disk, making them extremely difficult to spatially resolve and study. Sudden increases in the luminosity of the central star will quickly expand the sublimation front (so-called snow line) to larger radii, as seen previously in the FU Ori outburst of the young star V883 Ori. In this paper, we take advantage of the rapid increase in disk temperature of V883 Ori to detect and analyze five different COMs, methanol, acetone, acetonitrile, acetaldehyde, and methyl formate, in spatially-resolved submillimeter observations. The COMs abundances in V883 Ori is in reasonable agreement with cometary values. This result suggests that outbursting young stars can provide a special opportunity to study the ice composition of material directly related to planet formation.
The earliest phases of star formation are characterised by intense mass accretion from the circumstellar disk to the central star. One group of young stellar objects, the FU Orionis-type stars exhibit accretion rate peaks accompanied by bright eruptions. The occurrence of these outbursts might solve the luminosity problem of protostars, play a key role in accumulating the final star mass, and have a significant effect on the parameters of the envelope and the disk. In the framework of the Structured Accretion Disks ERC project, we are conducting a systematic investigation of these sources with millimeter interferometry to examine whether they represent normal young stars in exceptional times or they are unusual objects. Our results show that FU Orionis-type stars can be similar to both Class I and Class II systems and may be in a special evolutionary phase between the two classes with their infall-driven episodic eruptions being the main driving force of the transition.
We have obtained ALMA Band 7 observations of the FU Ori outburst system at 0.6x0.5 resolution to measure the link between the inner disk instability and the outer disk through sub-mm continuum and molecular line observations. Our observations detect continuum emission which can be well modeled by two unresolved sources located at the position of each binary component. The interferometric observations recover the entire flux reported in previous single-dish studies, ruling out the presence of a large envelope. Assuming that the dust is optically thin, we derive disk dust masses of $2times 10^{-4}$M$_{odot}$ and $8times 10^{-5}$M$_{odot}$, for the north and south components respectively. We place limits on the disks radii of $r<$45 AU. We report the detection of molecular emission from $^{12}$CO(3-2), HCO$^{+}$(4-3) and from HCN(4-3). The $^{12}$CO appears widespread across the two binary components, and is slightly more extended than the continuum emission. The denser gas tracer HCO$^{+}$ peaks close to the position of the southern binary component, while HCN appears peaked at the position of the northern component. This suggests that the southern binary component is embedded in denser molecular material, consistent with previous studies that indicate a heavily reddened object. At this angular resolution any interaction between the two unresolved disk components cannot be disentangled. Higher resolution images are vital to understanding the process of star formation via rapid accretion FU Ori-type episodes.
We present ALMA observations of 12CO, 13CO, and C18O J=2--1 lines and the 230 GHz continuum for the FU Ori-type object (FUor) V900 Mon (d~1.5 kpc), for which the accretion burst was triggered between 1953 and 2009. We identified CO emission associated with a molecular bipolar outflow extending up to a ~10^4 au scale and a rotating molecular envelope extending over >10^4 au. The interaction with the hot energetic FUor wind, which was observed using optical spectroscopy, appears limited to a region within ~400 au of the star. The envelope mass and the collimation of the extended CO outflow suggest that the progenitor of this FUor is a low-mass Class I young stellar object (YSO). These parameters for V900 Mon, another FUor, and a few FUor-like stars are consistent with the idea that FUor outbursts are associated with normal YSOs. The continuum emission is marginally resolved in our observations with a 0.2x0.15 (~300x225 au) beam, and a Gaussian model provides a deconvolved FWHM of ~90 au. The emission is presumably associated with a dusty circumstellar disk, plus a possible contribution from a wind or a wind cavity close to the star. The warm compact nature of the disk continuum emission could be explained with viscous heating of the disk, while gravitational fragmentation in the outer disk and/or a combination of grain growth and their inward drift may also contribute to its compact nature.
We have studied the environment of the FU Ori type star V582 Aur. Our aim is to explore the star-forming region associated with this young eruptive star. Using slitless spectroscopy we searched for H alpha emission stars within a field of 11.5arcmin times 11.5arcmin, centred on V582 Aur. Based on UKIDSS and Spitzer Space Telescope data we further selected infrared-excess young stellar object candidates. In all, we identified 68 candidate low-mass young stars, 16 of which exhibited H alpha emission in the slitless spectroscopic images. The colour-magnitude diagram of the selected objects, based on IPHAS data, suggests that they are low-mass pre-main-sequence stars associated with the Aur OB 1 association, located at a distance of 1.3 kpc from the Sun. The bright-rimmed globules in the local environment of V582 Aur probably belong to the dark cloud LDN~1516. Our results suggest that star formation in these globules might have been triggered by the radiation field of a few hot members of Aur OB 1. The bolometric luminosity of V582 Aur, based on archival photometric data and on the adopted distance, is 150-320 Lsun.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
