Two questions

So far we've been subjected to gamma ray Burst ( that would probably be fatal to
civilizations living near by one), Magnetstars, Eta Carina , an exploding star
whom astro-physist think might be acting has a huge ultraviolet laser, Black
holes, Neutron stars, Novas and Supernovas.

I'm wondering ...how close can some stellar phenomena has to be before it can
represent a threat to life on this planet,and what's a safe distance that would
provide the people on this planet a spectacular light show but wouldn't
represent a danger to life here. Are there any particular candidates that we
should look out for?

Second question, I used to look at pictures of galaxies and marvel that all that
white hot gaseous looking stuff you see in a picture of a galaxy were stars. Now
I'm wondering if alot of that white hot "stuff" you see when looking at a galaxy
is just what it is ..white hot gas. Can the stars in a picture of a galaxy be
spotted individually, or are they truly too numerous too count.

"When I die, I would like to go peacefully in my sleep, like my grandfather did.
Not screaming and yelling like the passenger in his car." Jack Handey

D.Brown wrote in sci.astro:


I'm wondering ...how close can some stellar phenomena has to be before
it can represent a threat to life on this planet,and what's a safe
distance that would provide the people on this planet a spectacular
light show but wouldn't represent a danger to life here. Are there
any particular candidates that we should look out for?

Here's an excellent synopsis of the story answering your question. There
are some references to halfwits in the story, as it's a response to their
weird claims, but leave those out for yourself and you have a good
explanation.

http://www.badastronomy.com/mad/1996/sn.html


Second question, I used to look at pictures of galaxies and marvel
that all that white hot gaseous looking stuff you see in a picture of
a galaxy were stars. Now I'm wondering if alot of that white hot
"stuff" you see when looking at a galaxy is just what it is ..white
hot gas. Can the stars in a picture of a galaxy be spotted
individually, or are they truly too numerous too count.


"Normal" stars (not just supernovae) are "singled out" in other nearby
galaxies since long - dating back to Hubble - not the scope but the
man... For closer galaxies it's possible to get as detailed accounts of
individual stars, clusters and nebula as in our own galaxy.
Most pictures you see are indeed processed to make people marvel, often
leaving components too bright to be detailed out, just to show an overall
picture.



--
CeeBee


Uxbridge: "By God, sir, I've lost my leg!"
Wellington: "By God, sir, so you have!"


Google CeeBee @ www.geocities.com/ceebee_2

(Steve Willner) wrote in sci.astro:


This is a bit optimistic. Even in nearby galaxies, it's only the
brightest stars that can be individually resolved. HST can resolve
Cepheid variables at the distance of the Virgo cluster, for example.


Not quite true.

http://www.stsci.edu/stsci/meetings/...ennicuttr.html
Sadly the pictures seem to have dropped from the page.
The team describes that "beyond the Local Group the horizontal and
subgiant branches fall below the WFPC2 detection/crowding limit".

In the M31 halo it has been able to resolve old main sequence stars.

Also read:
http://www.fisica.uniroma2.it/astro/...6-maysymp.html

A nice example is the HST resolving stars in a globular cluster orbiting
M31:
http://seds.lpl.arizona.edu/messier/...031_g1hst.html

And a nice one also of the M100:
http://www.ast.cam.ac.uk/HST/IMAGES/M100Color.gif
http://www.seds.org/hst/WFPCM100Mosaic.html


Hubble himself was able to resolve only the brightest stars in nearby
galaxies, like Cepheids, HST goes well beyond that.

--
CeeBee


Uxbridge: "By God, sir, I've lost my leg!"
Wellington: "By God, sir, so you have!"


Google CeeBee @ www.geocities.com/ceebee_2