Not really, the whole “things moving faster further away from us” only applies to the things furthest away from us, not at all our neck of the woods. The physics that governs that phenomenon is irrelevant within the local group and certainly within our galaxy, so it doesn’t really tell us anything about how we map our own galaxy.

> Stuff farther away moves faster away than stuff closer to us. So we know relative distances to us.

I blame this on poor science communication, but I see people talking about redshift being used to measure distances in all the wrong contexts.

Redshift ONLY works when measuring the distances to GALAXIES outside our local group. So relative velocities are meaningless even when talking about andromeda, much less stars in the milkyway.

> With an estimate of the gravity of the center of the milky way we can estimate how from out the hydrogen we observe must be for it to be moving at the velocity that it does.

This would be a terrible way of doing this since you have know the geometry and mass distribution of the galaxy to have a model of how stars should be rotating. On top of that, even if you had a good model, you only measure line-of-sight velocities, making this pretty useless.

Shame you are getting downvoted, these are mostly good points.

> I'm most fascinated by spectroscopy,

Ha! As an astronomer and primarily a spectroscopist, this warms my heart, but it is definitely a case of "one of these things is not like the others".

Without going too technical on the subject, the main things I think you should learn about spectroscopy are:

• Some basics on atomic physics, why we see discrete spectral lines from electronic transitions from different ions and molecules.
• The difference between spectral lines and continuous emission processes, such as blackbody radiation, bremsstrahlung, etc.
• Some basic radiative processes: where do we see these processes, what they look like, and what we can learn from an object based on these properties?
• How does motion affect these features (redshift and blueshift)
• Some basics of how spectrometers work.

I know its usually a bummer when someone recommends a textbook, but slightly more detailed spectroscopy is not really popular sci-comm. If I remember correctly, 21st century astronomy is a good entry-level textbook.

We definitely see outflows of material along the equator: disk winds! In fact, we think that in protoplanetary disks and accreting black holes, you can have winds and jets launched by the same magnetocentrifugal mechanism, where magnetic field lines coming out of the surface of the disk rotate while "anchored" to the surface and material is driven out centrifugally along the magnetic field line. The jet is then a special case where the opening angle of the global magnetic field closes around the rotation axis. This is not the only mechanism for driving jets, and certainly not the only way off driving winds though.

The key here is that jets are strongly thought to be a fundamentally magnetic process, where the strong magnetic field of the accretion disk near the accreting object interacts with the fastest rotating material in the disk. The magnetic field geometry of the disk is driven entirely by the rotation of ionized gas in the disk, so the close connection to the rotation axis of the disk is not incidental. Curiously, the jet does not have to be perfectly aligned, and the jet may be misaligned or begin precessing.

Another way to think about it is that everything in the disk is basically axially symmetric around the rotation axis. When the disk spits out material, it does the same in the form of winds. Jets are a special case of this.

Astronomer here.

Protostellar disks do have powerful winds and jets, the latter of which especially would produce a measurable blueshift and redshift exactly in the pattern you describe. However, protostellar disk jets tend not to be relativistic (maxing out at about 1000 km/s), while just the PROJECTED velocity required to produce shifts in this image is in 90,000 to 150,000 km/s (30% to 50% of the speed of light). This is based on the filters used to create this image. If there was a jet here, it would be detectable in spectroscopic data, but it wouldn't produce the dramatic color difference we see here.

From the press release, the blue light we see in the lower right is due to the fact that there is less dust (which tends to absorb bluer light) in that region.

I think I understand your question.

> How could you surpass JWST with dozens of telescopes that cost a few million each?

Unfortunately, it does not work quite like that. While optical interferometry is a thing, there is no universe where it would be more practical or economic to try to make a space-based IR interferometer to match the capabilities of JWST. People talk about interferometry like you just add telescopes together and magically you have a more powerful telescope, but the truth is that images produced by interferometric telescopes (especially optical) are incredibly difficult to produce and have huge limitations. So the use case here, while incredibly powerful, is actually quite specific and it is not a viable way to replace large telescopes in most use cases.

This is not to say that smaller, less expensive missions aren't essential. Advances on the detector side of the equation mean that we are able to produce small missions that are still very sensitive. Kepler, GAIA, and Spitzer all under a billion dollars. These have contributed vital science, although the first two with very specific uses, while the latter having a short lifespan and limited angular resolution (for a workhorse telescope).

On the X-ray side, missions like NuSTAR ran under $200 million, yet this mission has incredible timing properties, can detect X-rays over a huge energy range, and can look at very bright objects without degrading the quality of the data (a huge issue for X-ray telescopes). Missions like SWIFT (>$200 million) are vital for transient X-ray sources (such as a nearby accreting black hole that has gone into outburst), allowing you to quickly get a rough idea of what the object is doing before deciding to point a much more expensive telescope (like Chandra or XMM/Newton) at it.

As useful as these smaller mission are, however, you cannot evade the laws of physics. Optical systems are difficult and expensive to produce, require a lot of testing and calibration, they are incredibly heavy, and have inflexible spatial requirements (such as the location of the focal plane). I don't really see these specific aspects becoming cheaper in the near to mid-future, and the most sensitive and powerful missions push these aspects to the maximum, no way around it, really.

I do think that we could be more efficient about this. We lament, for instance, that once Chandra eventually ceases to work, no X-ray telescope will even come close to its resolving capabilities and we do not have anything (serious) planned to replace it. We spent so much money on facilities and R&D to build the optical system (which consists of the most perfect mirrors ever created by humanity), but now we kind of want to start from scratch for a replacement. Personally, I think we should plan to build a series of the same flagship telescope, just updating the electronic hardware for each iteration. This has worked efficiently in other missions, but I am sure there are large downsides to this approach.

Astronomer here.

We DO deploy LOTS of smaller missions at a much faster rate for significantly lower costs, you just don't hear about them as much.

Care to guess which missions still have the highest oversubscription rates? Its the flagship, billion-dollar missions like Hubble, Chandra, and JWST. Not because we prefer fancy expensive missions, but because they can do things cheaper observatories can't.