Radius of a main sequence star is proportional to the mass of the star. If you know the radius, you can pretty accurately get the mass. (It depends some on age and metallicity too, but not that much, as long as it hasn't evolved to a red giant yet.)

Planets, on the other hand, don't follow the rule nearly as well, especially for gas giants. Jupiter and a brown dwarf 80x the mass of Jupiter both have the same radius.

The discovery is very cool. I just dislike using "size" because it's unclear and dislike using "forbidden" because it sacrifices accuracy for sounding even cooler. An accurate headline that still sounds cool(ish) would be "Massive planet orbiting small red dwarf, an extreme mass ratio that challenges planet formation". I'm sure a professional could clean that up a bit without using the word "forbidden".

But it's still a very cool discovery.

By r^3 , sure, but if a star is 4x the radius, it's 64x the volume, so whether you meant "4x the size" meaning radius or "4x the size" meaning volume, the two are very different.

My first sentence is just my general complaint about space journalism that the word "size" is not clear because it could mean several things that are very different.

The paper itself admits that this could be the extreme end of our current models given known uncertainties and variabilities and therefore not "forbidden", but yeah, if they find a bunch of them, then we'll have to start tweaking models more.

In other words, good paper, bad headline and slightly hyperbolic article, as is typical for science journalism.

A white dwarf is a dead star that lost much of its mass though, so it's not really comparable. Gas giants will never form around a white dwarf, although secondary rocky planets might.

But even so, the definition of brown dwarf isn't necessarily set in stone. It definitely can't fuse normal hydrogen, but do you define the lower limit by the physical process, by formation mechanism, or by observational feasibility?

• Physical process: must be fusing deuterium? It's a nice physical process to define by. However, it's basically impossible to tell observationally whether a (potential) brown dwarf is burning deuterium. There are no outward signs. You can often measure mass, and the deuterium burning mass is approximately 13 Jupiter masses, but it depends on metallicity and age. Therefore, if you find an object that's around the limit, you're not sure what to call it without knowing metallicity or age, which is harder to do. Additionally, an older 13 M_J brown dwarf won't be fusing deuterium anymore, so does that mean it started as a brown dwarf and then became a planet when it burned all the deuterium in its core? That's not very satisfying.

• Formation mechanism: formed via disk instability/gravitational collapse (as opposed to core accretion)? There is very likely overlap in masses between high-mass core accretion objects and low-mass gravitational collapse objects. You could therefore have like a 10 M_J brown dwarf via gravitational collapse that has never fused deuterium, but a 15 M_J planet formed via core accretion that fuses deuterium. That's not very satisfying either to have an overlap in mass ranges.

• Observational: use 13 M_J as your cutoff? It's reasonable since that is generally the most observational characteristic that can somewhat distinguish the above scenarios. However, that means some your brown dwarfs formed via core accretion, while some planets formed via gravitational collapse. Similarly, it means that some of your brown dwarfs never fused deuterium, and some of your planets do fuse deuterium. Physically, it doesn't make sense to have either, but observationally, it's a very nice cutoff. Still, this isn't very satisfying either.

As far as I'm aware as a PhD in astronomy in exoplanets, there's not really an agreed-upon consensus among these three choices of definition.

I don't like calling gas giant "failed stars". There are two ways to define a planet (at the high mass end; edit: 3 ways, see lower comment):

1. If it formed from core accretion in a disk, it's a planet. (Conversely, if it formed from disk instability and gravitational collapse, it's not a planet.)
2. If it's under the mass required to fuse deuterium (~13 Jupiter masses), it's a planet.

Both definitions have pros and cons. Since we typically think of gas giants as planets that formed via core accretion, I wouldn't call any of them "failed stars" since they form completely differently than actual stars.

However, if a nominal gas giant formed via disk instability/gravitational collapse, but doesn't burn regular hydrogen, then "failed star" is appropriate.

So "size" in this context means radius of the star vs. planet, not the mass, area, or volume.

I think calling it "forbidden" is very hyperbolic. It's at the extreme end of what we know, but it's not unreasonable for it to form as such under current planet formation theories given reasonable uncertainties and variability.

Because it's cold. It's a joke off of yesterday's post.

Never got the "there's such good weather outside" posts anyways. Like, I don't need to check Reddit to learn about the weather right now.

> inside

Fine for me.

That happened to me a few months ago. It happened to be at the same time as competitors were installing services in the building, so maybe that?

Yeah, that's the mathematical version. Mine is the programming version.

Police reform != criminal justice reform.

Reddit is not reality. The people in this subreddit are highly unrepresentative of DC residents as a whole.

No idea. I haven't seen the video to know how bad it is, but by the pre-response, it's probably bad.

However, relative to the George Floyd murder:

• The cops have already been arrested, which negates one major purpose of potential protests

• The cops are Black, which works to lessen the racial animosity this could provoke (then again, anecdotally, white cops seem to get arrested less than POC cops for similar crimes, so maybe that'll piss people off too).

• However, there's also been very little actual police reform since George Floyd, and most police departments across the country have had their budgets increased, so there might be anger at the lack of response from 2.5 years ago.

And the questions are so weird. Many questions are hyper-specific.

Not like it's going to be enforced.

Yeah, totally stalking you in a thread that I commented in before you.

But you didn't answer the question.

Soccer can hurt people. Do you want to ban soccer in the name of safety?

I also briefly talked about the two I did go to, but either way, people downvoting it? Come on. This subreddit is full of very rude people.

I don't really care about the internet points themselves, but I like calling out unfriendly behavior.

And apparently, this subreddit thinks I deserve being downvoted simply for not knowing about restaurants.

¯\_(ツ)_/¯

Let's see which ones I've heard of or been to:

Heard of:

• #24: Le Diplomate
• Bantam King/Daikaya/Haikan/Hatoba: But only heard of Bantam King/Daikaya
• Makan
• Rasika
• Sura

Been to:

• Moon Rabbit: Just went there last week for restaurant week lunch. Had a 3-course meal. Was really good. Great banh mi and good snickerdoodle cookie.
• Thip Khao: It's okay.

So heard of 7% of them, but only been to 2% of them.

Edit: So apparently, I'm getting downvoted just for mentioning that I don't know of mostly upscale restaurants. Cool, cool, guess I'm not elite enough for the /r/washingtondc crowd.

I've literally heard of one of these: Le Diplomate.

Edit: People are literally downvoting me for not having heard of more fancy restaurants?

My question is whether they'll actually work legally or keep giving me tickets and towing me for being legally parked.