Starship Asterisk*

Where does the following equation come from ? The period of an orbiting body is inversely proportional to the square root of the average density of matter inside its orbit. P = ( (mass/volume )1/2 )-1 Where are those superscripts when you need them? This equation may come Newton's and Kepler's Laws,...

Am I getting closer? Yes, but not there yet... Let's do some numbers: The average density inside earth's orbit is http://upload.wikimedia.org/math/b/2/a/b2ac4536e0a3dd7e67a7d0078fa865d0.png /(1.612 AU) 3 mostly due to the Sun. Mercury has an orbital period of 0.241 years so the average density insi...

It would seem to me to be unlikely that a cometary impactor consisting mostly of water ice and dry ice with a small iron core would have the potential to reach the core of Mars. If it were traveling fast enough, the friction heat from the initial impace would likely cause most of the volatile mater...

Thanks to both Ann and Art. Now I understand my confusion. I thought "dwarf" was reserved for stars of the same type that are runts and "white dwarf" was reserved for degenerate stars. As Ann clearly pointed out, I was wrong. The problem with any science that is rapidly changing ...

I am still confused. I thought O7 dwarfs came from intermediate mass stars (1 to 8 Msolar). O7 dwarfs are very recently evolved white dwarfs that are still very bright. But yet previously mentioned O7 dwarf's progenitor is a star of about 30 solar masses. How is this possible ?

Chris, thanks for your input, especially about the "calculator". I was somewhat sure that it did not account for energy transfer inside the planet. I am not in total agreement with your view of tectonics on Mars. The Valles Marineris indicates to me that the crust cracked and collapsed. It...

Since the forum is being engaged in star evolution and O and B type stars, I am asking a supposely simple question. Why do stars have different masses. A simple answer would be that there are different sizes of interstellar molecular clouds and hence, protostar disks. But any newly forming star must...

Hello Chris, Since you are the asteroid expert you may have some ideas about collisions occurring on Mar. I am begging for a response from this unfinished thread of thought. The "calculator" given me by Bmaone actually aided my ideas but may have led me off the track. Not sure.

Planetary nebulas are generated from lower mass stars and supernovas come from higher mass stars such as O and B types. So then we can safely say that Wikipedia is in error when it stated that the central star of the Cat's Eye Nebula is an O7 + [WR] type star ? <<The ejected gases form a cloud of m...

You explained exceedingly well the correspondence of a star's spectral class, luminosity, and metallicity. And now I know much more detail about the branches of the Hertzsprung-Russell chart. Thank you so much, Ann.

I will accept your explanation that I am not seeing true polar jets.

Chris, is Wikipedia correct in stating that the central star is a O7 + [WR] type star ?

Sirius A star is an A type star twice as large as our Sun. It companion star, Sirius B, is a white dwarf. Obviously, Sirius A is a long-lived star like our Sun - although it may have a shorter life because it is more massive. Sirius B being a white dwarf was a star the size of our Sun or Sirius A. S...

I understand all that you stated. Planetary nebulas are generated from lower mass stars and supernovas come from higher mass stars such as O and B types. So then we can safely say that Wikipedia is in error when it stated that the central star of the Cat's Eye Nebula is an O7 + [WR] type star ? Ann,...

Thanks for your prompt and precise answers. I have a difficult time not believing that opposing polar jets are indicated in APOD 2011 April 24 - The Cat's Eye Nebula from Hubble. These jets may have their origin in the magnetic fields inside the "bubbles" and not directly from the star. Wi...

According to Wikepedia IC 1101 does exist and is 50 times the size and 2000 times the mass of our Milky Way galaxy. Tis true. I do not know how astronomers know these parameters of a galaxy located near the limits of the known universe. This galaxy is a definite anomaly supposely caused by the colli...

Mature galaxies have most or all their stars consisting of Population I stars with high metallicity. In other words, most of the super-massive and massive stars have exploded and created through nucleosynthesis the higher metals. Mature galaxies also exhibit less gas and dust; i.e., either the mater...

Please refer to APODs 2011 April 24 and 2010 May 9. I have one very basic question. How does one know whether a nebula is t a supernova remnant or a planetary nebula resulting from the red giant phase of a star ? What can possibly cause the polar jets indicated in APOD 2011 April 24 ? Polar jets are...

[quote="Ann"] I'm sure that I haven't read that massive stars suffer multiple core collapses. On the other hand, "core collapse" is only a term. You are definitely right that the core of a massive star must suddenly shrink and heat on several occasions, and after each "sudd...

dougettinger wrote:This is an interesting question. I will restate the question. In the same time period, let's say 1000 years, are there more novae or supernovae in our Milky Way galaxy. I believe the answer may vary with the type of galaxy and the age of the universe. Novas are much more common t...

It is hard to believe that juggling shock waves and gravity for millions of years creates EGGs. I believe that EGGs occur almost spontaneously ( in cosmic time ) around a chunk of condensed higher metals similar to a rain droplet forming around a dust particle.

Art, have a happy Easter. Doug

If these dark or opaque clouds or globules are so tenuous and non-threatening, what indeed does trigger star birth at the tip of an elephant trunk and create the concentration of gases and dust behind it ?

Wow, Art, you are indeed the master quotidian quotationist. You certainly did you homework. I believe I need to learn to do more googling. Thank you. Doug I can comprehend the "elephant trunks" or "cone nebula" better by envisioning an intake fan at the tip of the cone that sucks...

Why do different elements become ionized at different distances from a star? Does each element as you see it farther from a star need less UV and less heat to be ionized ? The way I understand it, nitrogen requires less UV than hydrogen to become ionized, and therefore ionized nitrogen will typical...

Wikepedia does not have good answers to the above questions. I am still hoping for some response. Easter is around the corner; here is your chance to decorate some EGGs.

Just ran it myself for an impactor that is 2400km or 2,400,000m comprising porous rock and came up with an impact crater that would be (1.15k x 10(7))11,500k or 11,500,000m and Mars is 6800k diameter. Something the size of Pluto would very likely obliterate Mars Maybe I used the wrong units. I am n...