Fledgling stars try to prevent their neighbors from birthing planets

Fledgling stars try to prevent their neighbors from birthing planets
A artist's impression of an evaporating protoplanetary disc. Credit: NASA/JPL-Caltech/T. Pyle (SSC)

Newly formed stars are surrounded by a disc of dense gas and dust. This is called the protoplanetary disc, as material sticks together within it to form planets.

Stars of different shapes and sizes are all born in huge star-forming regions. Scientists know that when a protoplanetary disc around a relatively small star is very close to a massive star, the larger star can evaporate parts of the protoplanetary disc.

However, it was thought this was only the case where very large shone on the protoplanetary disc. Now, researchers led by Imperial College London have discovered that a protoplanetary disc shone on by only a relatively weak star is also losing material. The studied, called IM Lup, belongs to a star similar to our Sun.

The researchers estimate that the disc will lose about 3,300 Earth's worth of material over its 10-million-year lifetime, despite the light from the nearby star being 10,000 times weaker than stars usually caught stripping discs.

Lead author Dr Thomas Haworth from the Department of Physics at Imperial said: "Because the light shining on this disc is so much weaker than that shining on known evaporating discs, it was expected that there would be no evaporation. We have shown that actually these stars can evaporate a significant amount of material.

"This result has consequences if we want to understand the diversity of exoplanet systems that are being discovered. This phenomenon could significantly affect the planets that can form around different stars. For example, light from nearby stars could limit the maximum size a solar can be."

Fledgling stars try to prevent their neighbors from birthing planets
IM Lup's 'fuzzy halo'. Credit: Ilse Cleeves

The IM Lup system was studied recently by Dr Ilse Cleeves at Harvard, who discovered an unexplained 'halo' of material around it.

Working with Dr Cleeves, and researchers from the Max Planck Institute and the University of Cambridge, Dr Haworth modelled the flow and chemistry of the system to determine if the halo was the result of a nearby weak star heating up the system and evaporating away material.

They found that the halo is the result of evaporation, as material streams away and is lost to space. The team think the reason this disc is being strongly evaporated is that it is very wide.

When talking about solar systems or discs, distances are usually measured in astronomical units (AU), with one astronomical unit being the distance from the Sun to the Earth. The distance out to Pluto is about 40AU, whereas IM Lup's disc reaches out to about 400AU.

This means the star cannot hold on to the disc's outer parts so strongly, as its gravity would be much weaker that far out, leaving the fringes at the mercy of evaporation.

Dr Haworth said: "Our calculations show that if the disc started at 700AU in size, it would halve in size in the first million years of its life. Since IM Lup is less than a million years old, we've caught it in the act of rapid shrinking."


Explore further

Planet formation in Earth-like orbit around a young star

More information: Thomas J. Haworth et al, First evidence of external disc photoevaporation in a low mass star forming region: the case of IM Lup, Monthly Notices of the Royal Astronomical Society: Letters (2017). DOI: 10.1093/mnrasl/slx037
Citation: Fledgling stars try to prevent their neighbors from birthing planets (2017, March 22) retrieved 18 July 2019 from https://phys.org/news/2017-03-fledgling-stars-neighbors-birthing-planets.html
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RNP
Mar 22, 2017
An open access copy of the paper can be found here: https://arxiv.org...3409.pdf

Mar 22, 2017
Lost me on the title. "Fledgling stars try to prevent their neighbors from birthing planets" This applies a sense of intelligence with in a "Fledgling Star" and "birthing planets" Since this is obviously not the case it indicates the entire article is full of magical nonsense.

RNP
Mar 22, 2017
@bschott
Define "very close" please.

This is a phrase invented by the writer of the article for what the paper calls "a weak external radiation field" (no mention of individual stars).

Basically they are claiming photons from a star outside the system "evaporate" (which I can only assume they mean ionize) disk elements in the system....so why does the inner disk not "evaporate" MUCH faster given it's proximity to the star at the center of it?


They DO mean evaporate. Most of the gas concerned is already ionized (I am surprised you did you not realize!), so incoming radiation heats it rather than ionizing it. See the Wikipedia page for an easy to understand description of the process: https://en.wikipe...poration

BTW. The inner disk of new stars ARE largely cleared out by photoevaporation.

Mar 22, 2017
On a better note. The original paper is great. This article which the author seems to have left there name off is a disgrace. Also a note to Phys.org. Really? Really? with all the damn misinformation and "fake news" you are going to use Ads by Adblade????? WTF are you trying to be a trashy store shelf rag? You can do better. You better do better. Or I will just stop coming here.

RNP
Mar 22, 2017
@PoppaJ
I think both bschott and I misinterpreted you first post. Apologies on my part. I wonder how bschott feels?

RNP
Mar 22, 2017
@bschott
Your link just showed that what I said is correct that they are paraphrasing evaporation/ionization. (don't know about the second part as dispersing it "away from the source" would kick it towards the fledgling star).


NO! Evaporation and ionization are completely different things, and the authors, being real scientists, would never confuse the two.

The fact that you admit that you "don't know about the second part " in the Wikipedia page is the whole point. You have not considered all the physics, and consequently do not know what you are talking about.

The idea that the effect of an external radiation field on gas in the disk is to "kick it towards the fledgling star" is another example of your making ridiculous claims about subjects about which you have no understanding.

Mar 22, 2017
Stupid title. Fledgling stars don't 'try' to do anything. They don't have volition.

Mar 23, 2017
"The larger star can evaporate parts of the protoplanetary disc." from article

It is interesting that scientists always (almost always) take the opposite and wrong conclusions, they all are working upside down.
Stars collect material, they do not lose their material. The rotation of the star (the body) creates arranged disks of gas, asteroid belts and body in orbit.

"Why is there a ring, an asteroid belt or a drive around the celestial objects?"
https://www.acade..._objects

Mar 23, 2017
Stars collect material, they do not lose their material.


Sun loses material all the time. It's called the solar wind. In theory, our solar system began as a protoplanetary disk, most of which was blown away as Sun warmed.

RNP
Mar 23, 2017
@bschott
he whole point is that I said they meant ionization when they said evaporation in my first post, you said they didn't in your response.


You STILL have not understood either the article OR my posts OR the Wikipedia page. They DO mean evaporation. I repeat; they DO mean evaporation, NOT ionization.

RNP
Mar 23, 2017
@bschott
Photoevaporation denotes the process where energetic radiation ionises gas and causes it to disperse away from the ionising source.


How many times do I have to say this? As the Wikipedia quote above that you keep posting says, photoevaporation is when the gas is DISPERSED. The ionization is irrelevant. I.e. Dispersed means evaporated. Get it now?

RNP
Mar 23, 2017
@bschott
You are now engaging in serious obfuscation. I have REPEATEDLY said that evaporation means evaporation, NOT ionization. If your whole argument is based on your misunderstanding of a single word used on a Wikipedia page then you really have no argument.

RNP
Mar 23, 2017
@bschott
You do realize that a gas CAN"T evaporate right?


WHAT?? No wonder you are confused. You have completely failed to understand the context in which the word "evaporate" is being used.

First, note that one definition of evaporate given in dictionaries is "to disappear; vanish; fade".

Therefore the term "photoevaporate" used in the paper, and astrophysics in general, simply means radiation making gas "disappear" from clouds of gas or galaxies in general. I.e. Radiation heats the gas to the point it "evaporates" away from the gravitational potential well to which it is bound (Note that whether or not the gas is ionized in the process is irrelevant, although it almost always is).

At least I now understand one thing... given your lack of comprehension of the physics being described in the paper and the language being used, it is small wonder that you have not understood a word that anybody has been saying to you!!!!!!

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