When I think of a brown dwarf I think of a stellar body that doesn’t have quite enough mass to become a full fledged star. Now it seems there is an example of a brown dwarf being formed because a companion has taken so much mass from a regular star it has actually been downgraded according to researchers.
Astronomers have detected a sub-stellar object that used to be a star, after being consumed by its white dwarf companion.
An international team of astronomers made the discovery by observing a very faint binary system, J1433 which is located 730 light-years away. The system consists of a low-mass object – about 60 times the mass of Jupiter – in an extremely tight 78-minute orbit around a white dwarf (the remnant of a star like our Sun).
Due to their close proximity, the white dwarf strips mass from its low-mass companion. This process has removed about 90 per cent of the mass of the companion, turning it from a star into a brown dwarf.
Most brown dwarfs are ‘failed stars’, objects that were born with too little mass to shine brightly by fusing hydrogen in their cores. By contrast, the brown dwarf in this system was born as a full-fledged star, but has been stripped to its current mass by billions of years of stellar cannibalism. Continue reading →
Researchers using the Atacama Large Millimeter/submillimeter Array (ALMA) have made the first direct observations delineating the gas disk around a baby star from the infalling gas envelope. This finding fills an important missing piece in our understanding of the early phases of stellar evolution.
A research team, led by Yusuke Aso (a graduate student at the University of Tokyo) and Nagayoshi Ohashi (a professor at the Subaru Telescope, National Astronomical Observatory of Japan) observed the baby star named TMC-1A, which is located 450 light-years from Earth in the constellation Taurus. TMC-1A is a protostar, a star still in the process of forming.
The team directly observed the boundary between the inner rotating disk and the outer infalling envelope. Since gas from the outer envelope is continuously falling into the disk, it had been difficult to identify the transition region in previous studies. In particular, the tenuous but high-speed gas in rotating disks is not easy to see. But ALMA has enough sensitivity to highlight such a component and illustrate the speed and distribution of gas in the disk very precisely. This enabled the team to distinguish the disk from the infalling envelope.
A reflection nebula is an interstellar dust cloud that is reflecting light from a nearby star. In this case, a young star is lighting up IC2631 and is shown by this great image from the ESO.
A newly formed star lights up the surrounding cosmic clouds in this image from ESO’s La Silla Observatory in Chile. Dust particles in the vast clouds that surround the star HD 97300 diffuse its light, like a car headlight in enveloping fog, and create the reflection nebula IC 2631. Although HD 97300 is in the spotlight for now, the very dust that makes it so hard to miss heralds the birth of additional, potentially scene-stealing, future stars.
WOW! Look just look at the results from the first light of the GRAVITY instrument, which essentially takes light gathered from multiple telescopes and combines it into a single image.
The caption released with the image:
As part of the first observations with the new GRAVITY instrument the team looked closely at the bright, young stars known as the Trapezium Cluster, located in the heart of the Orion star-forming region. Already, from these first data, GRAVITY made a discovery: one of the components of the cluster (Theta1 Orionis F, lower left) was found to be a double star for the first time. The brighter double star Theta1 Orionis C (lower right) is also well seen.
The background image comes from the ISAAC instrument on ESO’s Very Large Telescope. The views of two of the stars from GRAVITY, shown as inserts, reveal far finer detail than could be detected with the NASA/ESA Hubble Space Telescope.
The SPHERE instrument was recently installed on the VLT at ESO’s Paranal Observatory. The Spectro-Polarimetric High-contrast Exoplanet REsearch instrument or SPHERE for short was installed on Unit Telescope 3 of the VLT.
SPHERE is a very sophisticated instrument designed to spot exo-planets by direct imaging. SHPERE will have the ability to block out the central part of a given star to reduce its contribution. To make this very basic, the light coming from stars (including our sun) is not polarized but when that light is reflected off an exo-planet it becomes at least partially polarized and SHPERE can pick out the polarized signal. For a bit more detailed explanation look here.
From ESO: Some of the sharpest images ever made with ESO’s Very Large Telescope have for the first time revealed what appears to be an ageing star in the early stages of forming a butterfly-like planetary nebula. The observations of the red giant star L2 Puppis from the ZIMPOL mode of the newly installed SPHERE instrument are combined here with infrared data from NACO, also on the VLT, which shows a dust loop deployed on the far side of the upper part of the nebula. The dying stages of the lives of stars continue to pose many riddles for astronomers.
This image is the Boomerang Nebula, a product of ALMA and Hubble. The Boomerang is 5,000 light-years away in the constellation Centaurus. Click the image above to see the Hubble image without the ALMA data, you will also see why it also has the name of the Bow Tie Nebula.
The Boomerang is a protoplanetary nebula, a confusing term because it does not mean it is forming planets, it’s between the (asymptotic) giant phase and the planetary nebula phase. The cool thing about the Boomerang is not just cool it is cold. It is the coldest place we know of, 1 degree Kelvin and that’s -272.15 C / -457.87 F, the atoms are just barely moving!
I also can’t help thinking I saw an episode of Star Trek with a creature that looks a lot like the ALMA addition.
Image: Bill Saxton; NRAO/AUI/NSF; NASA/Hubble; Raghvendra Sahai
Astronomers used the ESO’s Very large Telescope in Chile took this “most detailed” image of the Medusa Nebula.
The colorful nebula cloud is from the the central star that has puffed off its outer layers, just like our Sun will do far in the future.
This nebula is off the “knee” of Pollux in the Gemini constellation. The ESO team put out a wide-field view that is amazingly good and more inline with what you would see in a telescope although way-way better of course. (Credit: ESO/Digitized Sky Survey 2) It in my opinion pretty hard to see, at least it was for me and my scope.
Most stars with masses similar to that of our Sun will end their lives as white dwarfs — small, very dense, and hot bodies that slowly cool down over billions of years. On the way to this final phase of their lives the stars throw their atmospheres out into the space and create planetary nebulae, colourful glowing clouds of gas surrounding the small, bright stellar relics.
We can now see Rosetta’s goal, comet 67P/Churyumov-Gerasimenko thanks to researchers from the Max Planck Institute for Solar System Research and the European Southern Observatory. The comet disappeared behind the sun last October and it is just now out of the glare enough to be seen.
They took the image above with ESO’s Very Large Telescope. Actually the image is several exposures stacked together. Think of it is adding all the images together to bring out the features. 67P/Churyumov-Gerasimenko is small, around 3 x 5 km and it is about 740 million km / 460 million miles so it is very faint.
The new image suggests that 67P is beginning to emit gas and dust at a relatively large distance from the Sun – Colin Snodgrass from the MPS
The comet will become more visible to researchers as it gets closer.