galaxy model

[dr wogz]

Hi All,

just curious, does anyone know of a computer model of our galaxy showing what parts we've studied / had a really good look at? I assume someone has taken a model of our galaxy, and have imposed some geometry onto it to show what we've explored / contemplated as being interesting. I'm assuming we've only looked at a few stars, and a few areas of our galaxy. (Some 3D map of where the Hubble has been looking, where other observatories have been looking, how deep into, and the limits of the "looking around"..

 

[Funkworks]

Not sure this answers your question, but generally speaking, most of the stars astrophysicists study belong to our galaxy, but instead of selecting stars by their "location within the galaxy", they choose stars based on the light they emit, especially light intensity and color spectrum (emission spectrum), and the color spectrum is directly related to the star's temperature (a blue flame is hotter than a red one).

The first really amazing thing they teach in astrophysics is the Hertzsprung–Russell diagram, because it sets out a startling relationship between a star's brightness and its temperature. The punchline: almost every star falls onto the graph's diagonal line i.e. it's not a mess out there, there's order and logic.

https://en.wikipedia.org/wiki/Hertzsprung–Russell_diagram
So, instead of its location, a star's classification is based on its position in the Hertzsprung–Russell diagram. Detailed study of this over decades lead to the result that a star's position on the H-R diagram is based on nothing but its initial mass, and age. Its precise composition and a few other things can be factors, but basically, intensity and color spectrum, based on mass and age, is how stars are classified.

 

[Charles_McG]

The Gaia satellite has been collecting position and parallax info on billions of stars with enough sensitivity to directly measure distance a long way across the galaxy. It has enough data points it's hard to tell from simulations/art.

https://www.esa.int/Science_Explora...tes_richest_star_map_of_our_Galaxy_and_beyond

 

[Alan15578]

As a follow up question, how many stars are "cataloged". and how many are being added yearly?

 

[Funkworks]

I just looked it up and found the answer to be about 219 million, as of 2014.

https://www.universetoday.com/11460...most-detailed-catalogue-of-our-milky-way-yet/

 

[dr wogz]

Thanks guys, I will add these to my coffee break readings..

But not exactly what I'm after..

I'm curious as to how far out and in what directions we've pointed our 'looking glasses'. I remember seeing a 2D graphic of the Hubble's scope, and it was just a small wedge fro mour solar system.. (Mind you this was years ago!)

it's one this to talk about which ones you looked at, what you've studied, what is interesting... But where is it relative to us?

For example: I will walk all over Montreal, and will report back my findings, observations, etc. You can read along, but you have no scope if I just walked around the block, down one street, or if I did truly take a "walk"! Not knowing the city, and without looking up each individual address you have no idea how far i've gone, or in what direction(s).. But if I show you on a map where I've been (like on the STRAVA app) you get a good idea that I am either lazy, or training for the Olympics!

 

[Funkworks]

I suppose each and every recording telescope out there (Hubble and the others) has made a partial map. But each one has a different resolution. I think your question depends on what resolution you're expecting. If Hubble is still the best one out there, we only need to look at what Hubble's been up to since that 2D image you saw. Other telescopes also see in other wavelengths (X-rays, IR, radio), so it depends on whether you want a map of that radiation as well.

An important thing to consider is that since our galaxy is flat-ish, the middle part "obscures" the other half of the galaxy, so we'll always have much better images of our own half.

 

[Charles_McG]

Also, it depends on whether you mean position, distance, and true velocity of individual stars in our galaxy, which is what the Gaia satellite is really doing. That's how I first interpreted your question.

But several surveys, including Hubble work, have been mapping galaxies, rather than stars. Those surveys tended to look like wedges.
https://en.wikipedia.org/wiki/2dF_Galaxy_Redshift_Survey

 

[dr wogz]

Again, i thank you both. i guess there is just much more to it that I figure.. (Which I expect!) Deep views aside, only interested in our galaxy. And, 'just mapping surveys' excluded as well. What re the intersting points we've spent time studying..

What I'm after is to know how far in to the cosmos we've looked, and what portions have been mapped, without having to know exactly what all the terminology, technology, science really is.. Something that can easily explain / show a kid where we've looked / studied..

it's one thing to follow Hubble or others, and read about what they've found, why they studied it, the interesting points, etc.. But nothing to exactly pin point where we are looking (unless you open / search each point of interest, and plot your own map) I just figured someone has done a model to show, roughly, where we've pointed our telescopes.

I kinda figure there is an image out there that kinda looks like this (see below) that has the portions of the sky we've studied.. The green globe (representing our solar system or some 'relative point') would have extended wedges or slices looking out, to show where & how far we have had it pointed for a while.. Some quick reference to show, for instance, that we look more to the left, or right of our spiral arm, and that we tend to look inwards, rather than outwards, that Hubble tends to have a range of "half an inch" (scaled to the picture of the galaxy) into the spiral arm, etc..

Of course, this also begs to ask, if anyone has done a 'points of interest' type maps of the galaxy, to see where in relation a lot of the really interesting things are, like a tourist map, denoting the favorites spots, restaurants, etc.. so you can get an idea of what is in the vicinity of a truly interesting point..

 

[Funkworks]

Maybe a another starting point:
https://solarsystem.nasa.gov/resources/285/the-milky-way-galaxy/

 

[Charles_McG]

I think you have to define 'spent time studying' , and 'interesting' better. Kepler looked at 150,000 stars in the direction of cygnus for several years straight. And discounting 'surveys' can overlook a lot. Some things you only learn in bulk.