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25

There are three main reasons why we can tell that local stars did not, for the most part, form from the same molecular cloud that the Sun formed from. The first is that unless stars are born in a very tightly bound system such as a globular cluster (which the Sun is definitely not in), they will drift apart from their birth companions over time in slightly ...


19

Is it possible that the Sun and all the nearby stars formed from the same nebula? No, it is not. Our Sun has marked differences in metals compared to the nearby stars. (In astronomy, every element higher than helium is a "metal".) The discovered and analyzed stars that appear to be most similar to the Sun are far, far away from the Sun. Our Sun ...


13

Rudolf Minkowski. Its not likely to be the mathematician, Hermann. Nor the physiologist Oskar. There's only one Minkowski who was an observational astronomer. The paper describing M1-92 was https://iopscience.iop.org/article/10.1086/125855 The 2006 paper on Minkowski's object (Croft et al) cites Minkowski, R. 1958, PASP, 70, 143


9

There are two phases to this problem. In order to accrete into stars, a huge amount of angular momentum must be lost to allow so much mass to gather into a small volume. A second problem is how stars like the Sun end up rotating so slowly, when younger versions of stars similar to the Sun rotate much faster. The solution to the first problem may be solved by ...


8

Annes Astronomy News says: Fleming 1 is a planetary nebula that lies about 10,000 light-years away in the constellation of Centaurus, while moving away from us at approximately 28.6 kilometers per second. It is named after the Scottish astronomer Williamina Fleming, who discovered the nebula in 1910. Williamina Paton Stevens Fleming (May 15, 1857 – ...


7

The Vela Pulsar (PSR J0835-4510 or PSR B0833-45) is a radio, optical, X-ray- and gamma-emitting pulsar associated with the Vela Supernova Remnant in the constellation of Vela. First line of the Wikipedia entry on the Vela pulsar. It's obviously much more spread out and diffuse than the Crab nebula because it occurred more than 10 times as long ago. Here it ...


4

This source, https://apod.nasa.gov/apod/ap190110.html, an astronomy Picture of the Day states that the Vela remnant "is likely embedded in a larger and older supernova remnant, the Gum Nebula".


4

A query to the Gaia Archive within 6 arc min of target name M51 finds 20 sources with phot_g_mean_mag <= 17. Aladin Lite helps to locate them visually. Five are circled in the lower half of the image in question: Gaia source_id ra ° dec ° parallax (mas) magg 1551894661845524736 202.4034 47.1522 8.854 ± 0.017 14.3 1551988532650838016 202.4205 47.1790 2....


2

The crab nebula is more than 6000 light years away. Its progenitor was probably towards the lower end of stars that go supernova. And according to the luminoisity calculator had a magnitude of about 8. This means that the progenitor was not visible to the naked eye. As only the brighter naked eye stars have ever been named, and this star was not seen before ...


2

Large objects can be very faint if they are far enough away. So large objects wouldn't necessarily be discovered a long time ago. The object you mentioned is very faint and required a long view time to acquire enough photons to "see" it. As stated in a comment by @Pierre Paquette, the object was viewed for over 59 hours.


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