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Re: Jupiter's Great Red Spot

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  Re: Jupiter's Great Red Spot David DeLaney <daviddelaney@earthlink.net> - 2017-07-18 03:40 -0500
    Re: Jupiter's Great Red Spot djheydt@kithrup.com (Dorothy J Heydt) - 2017-07-18 14:07 +0000
      Re: Jupiter's Great Red Spot Robert Woodward <robertaw@drizzle.com> - 2017-07-18 09:02 -0700
      Re: Jupiter's Great Red Spot David DeLaney <daviddelaney@earthlink.net> - 2017-07-18 14:13 -0500

#641185 — Re: Jupiter's Great Red Spot

On 2017-07-11, Greg Goss <gossg@gossg.org> wrote:
> djheydt@kithrup.com (Dorothy J Heydt) wrote:
>>As for the colors of planets (as seen through atmosphrere from
>>Earth, mind you), there used to be a saying among classic (I mean
>>Greco-Roman times), that three astronomical objects shone red:
>>Sirius, Mars, and Jupiter (but not as red)  Sirius is certainly
>>not red today, and current astrophysics has no explanation for a
>>star turning from bright red to bright blue-white.  If ever I
>>meet an astrophysicist, I'll ask him/her, "What's your
>>hypothesis," and if the answer is "I haven't got one," I'll take
>>that as an honest answer.
>
> Three red objects?  How about Antares ("not Mars") and Betelguese?

Astrophysics does have a hypothesis to cover that: namely, that in historical
times Sirius B was a red giant, that there was a nova (which doesn't seem to
have been recorded, but historical astronomy records are spotty in places),
which led to it becoming the white dwarf we currently see.

Would require fairly coincidental timing, but we already know we had that with
nearby _super_novae, a drought of which lasted from juuuust before the
invention of the telescope (Kepler's, 1604) to a few decades ago when SN1987A
popped in the Large Magellanic Cloud (and also showed up through neutrino
astronomy). So not actually impossible.

Dave, of course a nebular remnant should be visible and as far as I know isn't,
 but maybe alien space bats
-- 
\/David	DeLaney	posting	thru EarthLink - "It's not the pot that	grows the flower
It's not the clock that	slows the hour 	The definition's plain for anyone to see
Love is	all it takes to	make a family" - R&P. VISUALIZE	HAPPYNET VRbeable<BLINK>
gatekeeper.vic.com/~dbd	- net.legends FAQ & Magic / I WUV you in all CAPS! --K.

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#641208

In article <esqdnb_Sa6rvVPDEnZ2dnUU7-UfNnZ2d@earthlink.com>,
David DeLaney  <dbd@vic.com> wrote:
>On 2017-07-11, Greg Goss <gossg@gossg.org> wrote:
>> djheydt@kithrup.com (Dorothy J Heydt) wrote:
>>>As for the colors of planets (as seen through atmosphrere from
>>>Earth, mind you), there used to be a saying among classic (I mean
>>>Greco-Roman times), that three astronomical objects shone red:
>>>Sirius, Mars, and Jupiter (but not as red)  Sirius is certainly
>>>not red today, and current astrophysics has no explanation for a
>>>star turning from bright red to bright blue-white.  If ever I
>>>meet an astrophysicist, I'll ask him/her, "What's your
>>>hypothesis," and if the answer is "I haven't got one," I'll take
>>>that as an honest answer.
>>
>> Three red objects?  How about Antares ("not Mars") and Betelguese?
>
>Astrophysics does have a hypothesis to cover that: namely, that in historical
>times Sirius B was a red giant, that there was a nova (which doesn't seem to
>have been recorded, but historical astronomy records are spotty in places),
>which led to it becoming the white dwarf we currently see.

But what about the big blue supergiant that we now see?
>
>Would require fairly coincidental timing, but we already know we had that with
>nearby _super_novae, a drought of which lasted from juuuust before the
>invention of the telescope (Kepler's, 1604) to a few decades ago when SN1987A
>popped in the Large Magellanic Cloud (and also showed up through neutrino
>astronomy). So not actually impossible.

Coincidences do happen.  I can see a supernova happening *just*
long enough ago that its light shines on Earth and fades out
*just* before anybody has a telescope.  But what about the big
blue supergiant?

I don't know nearly enough about star formation.  What is a
protostar befor it turns into a blue supergiant?  If one of those
were sitting in a big dust cloud, would the light reaching Earth 
look red?

Is there an astrophysicist in the house?

-- 
Dorothy J. Heydt
Vallejo, California
djheydt at gmail dot com

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#641218

In article <otAHwq.14zF@kithrup.com>,
 djheydt@kithrup.com (Dorothy J Heydt) wrote:

> In article <esqdnb_Sa6rvVPDEnZ2dnUU7-UfNnZ2d@earthlink.com>,
> David DeLaney  <dbd@vic.com> wrote:
> >On 2017-07-11, Greg Goss <gossg@gossg.org> wrote:
> >> djheydt@kithrup.com (Dorothy J Heydt) wrote:
> >>>As for the colors of planets (as seen through atmosphrere from
> >>>Earth, mind you), there used to be a saying among classic (I mean
> >>>Greco-Roman times), that three astronomical objects shone red:
> >>>Sirius, Mars, and Jupiter (but not as red)  Sirius is certainly
> >>>not red today, and current astrophysics has no explanation for a
> >>>star turning from bright red to bright blue-white.  If ever I
> >>>meet an astrophysicist, I'll ask him/her, "What's your
> >>>hypothesis," and if the answer is "I haven't got one," I'll take
> >>>that as an honest answer.
> >>
> >> Three red objects?  How about Antares ("not Mars") and Betelguese?
> >
> >Astrophysics does have a hypothesis to cover that: namely, that in 
> >historical times Sirius B was a red giant, that there was a nova 
> >(which doesn't seem to have been recorded, but historical astronomy 
> >records are spotty in places), which led to it becoming the white 
> >dwarf we currently see.
> 
> But what about the big blue supergiant that we now see?

Sirius A is not a blue supergiant; it isn't even a giant, being a normal 
main-sequence A class star.

> >
> >Would require fairly coincidental timing, but we already know we had 
> >that with nearby _super_novae, a drought of which lasted from 
> >juuuust before the invention of the telescope (Kepler's, 1604) to a 
> >few decades ago when SN1987A popped in the Large Magellanic Cloud 
> >(and also showed up through neutrino astronomy). So not actually 
> >impossible.
> 
> Coincidences do happen.  I can see a supernova happening *just*
> long enough ago that its light shines on Earth and fades out
> *just* before anybody has a telescope. 

<snip>

> 
> Is there an astrophysicist in the house?

The Wikipedia article on the Sirius system 
(<https://en.wikipedia.org/wiki/Sirius> cites a paper in _The 
Astrophysical Journal_ 
(<https://en.wikipedia.org/wiki/Sirius#cite_note-Liebert2005-12>)that 
claims that Sirius B collapsed into a white dwarf about 120 million 
years ago.

-- 
"We have advanced to new and surprising levels of bafflement."
Imperial Auditor Miles Vorkosigan describes progress in _Komarr_.
‹-----------------------------------------------------
Robert Woodward robertaw@drizzle.com

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#641242

On 2017-07-18, Dorothy J Heydt <djheydt@kithrup.com> wrote:
> David DeLaney  <dbd@vic.com> wrote:
>>Astrophysics does have a hypothesis to cover that: namely, that in historical
>>times Sirius B was a red giant, that there was a nova (which doesn't seem to
>>have been recorded, but historical astronomy records are spotty in places),
>>which led to it becoming the white dwarf we currently see.
>
> But what about the big blue supergiant that we now see?

That's its partner, Sirius A, is it not?  ... no, Sirius A is a white main-
sequence, near our Sun's brightness, and is only the brightest visible star
for us because of its closeness. (And Wikipedia spikes my hypothesis,
apparently ~120 million years ago is currently accepted for Sirius B's nova.
Bah, back to the stellar-placement Lite-Brite!)

> Coincidences do happen.  I can see a supernova happening *just*
> long enough ago that its light shines on Earth and fades out
> *just* before anybody has a telescope.  But what about the big
> blue supergiant?

I am now not at all sure what you may be referring to. Checking, our nearest
known Big Blue is Rigel, in Orion, about 20 times Sol's mass. There is one in
Canis Major about 2000 light years away, but it's not Sirius.

> Is there an astrophysicist in the house?

Dave, no longer even plays a cousin of one in the sciences
-- 
\/David	DeLaney	posting	thru EarthLink - "It's not the pot that	grows the flower
It's not the clock that	slows the hour 	The definition's plain for anyone to see
Love is	all it takes to	make a family" - R&P. VISUALIZE	HAPPYNET VRbeable<BLINK>
gatekeeper.vic.com/~dbd	- net.legends FAQ & Magic / I WUV you in all CAPS! --K.

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