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Who's bright idea was it to call our galactic core's black hole "Sagittarius A Star"
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Dave Rove
Jun 17, 2013, 4:21:38 AM6/17/13
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Assuming that's how SGR A* is pronounced. It's as confusing in a
conversation as talking about your dog that you've named "My Ass".
conversation as talking about your dog that you've named "My Ass".
Mike Dworetsky
Jun 17, 2013, 5:08:13 AM6/17/13
to
Dave Rove wrote:
> Assuming that's how SGR A* is pronounced. It's as confusing in a
> conversation as talking about your dog that you've named "My Ass".
It's a very odd complaint. I can't see your point. Is your dog really
> Assuming that's how SGR A* is pronounced. It's as confusing in a
> conversation as talking about your dog that you've named "My Ass".
named that? I can see why it might be confusing, as in "I want to have fun
with (name of dog) and scratch its fur". The only persons you are ever
likely to discuss it with verbally are astronomers, and they will all know
what you mean.
The name originated, if memory serves, with radio and infrared astronomers
who needed to distinguish the galactic central bright object called Sgr A (=
brightest radio source in Sagittarius) and the western patch called Sgr A
West from a later discovery of an unresolved radio and infrared bright spot
within Sgr A, which was called Sgr A*. Not sure of the exact date without a
literature search, but probably in the 1980s.
--
Mike Dworetsky
(Remove pants sp*mbl*ck to reply)
Steve Willner
Jun 17, 2013, 3:22:24 PM6/17/13
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In article <o_ydnWlyybmfTyPM...@bt.com>,
according to the constellation and then in order of brightness.
Sgr A was thus the brightest radio source in Sagittarius.
When better maps came along about 1980, new names were needed. Sgr A
was broken into "Sgr A East," a nonthermal source, and "Sgr A West,"
which turns out to be a collection of H II regions near the Galactic
center.
A different scheme was used for Sgr B: we have Sgr B1 and Sgr B2.
Astronomical nomenclature doesn't always follow set rules, though
things are better now than a generation ago.
> who needed to distinguish the galactic central bright object called Sgr A (=
> brightest radio source in Sagittarius) and the western patch called Sgr A
> West from a later discovery of an unresolved radio and infrared bright spot
> within Sgr A, which was called Sgr A*.
The point source was discovered in 1974 (Balick & Brown, ApJ 194,
265). The discovery was based on limited interferometry data. Full
synthesis data came along about five years later. Bob Brown (1982
ApJ 162, 110) made up the name "Sgr A*" for the point source, and the
name stuck. I don't think it's so bad.
--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123 swil...@cfa.harvard.edu
Cambridge, MA 02138 USA
"Mike Dworetsky" <plati...@pants.btinternet.com> writes:
> The name originated, if memory serves, with radio and infrared astronomers
All radio. In the very early days, radio sources were named
> The name originated, if memory serves, with radio and infrared astronomers
according to the constellation and then in order of brightness.
Sgr A was thus the brightest radio source in Sagittarius.
When better maps came along about 1980, new names were needed. Sgr A
was broken into "Sgr A East," a nonthermal source, and "Sgr A West,"
which turns out to be a collection of H II regions near the Galactic
center.
A different scheme was used for Sgr B: we have Sgr B1 and Sgr B2.
Astronomical nomenclature doesn't always follow set rules, though
things are better now than a generation ago.
> who needed to distinguish the galactic central bright object called Sgr A (=
> brightest radio source in Sagittarius) and the western patch called Sgr A
> West from a later discovery of an unresolved radio and infrared bright spot
> within Sgr A, which was called Sgr A*.
265). The discovery was based on limited interferometry data. Full
synthesis data came along about five years later. Bob Brown (1982
ApJ 162, 110) made up the name "Sgr A*" for the point source, and the
name stuck. I don't think it's so bad.
--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123 swil...@cfa.harvard.edu
Cambridge, MA 02138 USA
Martin Brown
Jun 19, 2013, 6:19:33 AM6/19/13
to
On 17/06/2013 09:21, Dave Rove wrote:
> Assuming that's how SGR A* is pronounced. It's as confusing in a
> conversation as talking about your dog that you've named "My Ass".
>
Astronomers are a bit lazy and it might well be shortened to Sag A star.
> Assuming that's how SGR A* is pronounced. It's as confusing in a
> conversation as talking about your dog that you've named "My Ass".
>
They are the names given to objects in the first imprecise radio surveys
of the brightest objects giving them names of the form:
<constellation> <Roman letter>
A brightest, B second brightest etc. They tend to be very well studied
objects and the original names have largely stuck with them!
By analogy with bright stars which were <Greek letter><constellation>
Some of these objects are bright and extensively studied with modern
telescopes detailed so that the original name has stuck. Sgr A and it's
various components is one such as are SNR Cas A and radio galaxy Cyg A.
Later radio catalogues used <observatory tag><number> 3C461 and 3C405
respectively for the latter two in the third Cambridge catalogue. Or at
Parkes PKS 1548+05 (that's RA & Dec 1950.0 based)
Arguably it is more informative for humans to have constellation names
than some date of discovery or RA&Dec based long numeric string.
BTW: Why have you given your dog such a silly name?
--
Regards,
Martin Brown
Yousuf Khan
Jun 21, 2013, 12:10:09 AM6/21/13
to
On 17/06/2013 4:21 AM, Dave Rove wrote:
> Assuming that's how SGR A* is pronounced. It's as confusing in a
> conversation as talking about your dog that you've named "My Ass".
Well, I guess you could also call it SGR A asterisk, if you want. "Star"
> Assuming that's how SGR A* is pronounced. It's as confusing in a
> conversation as talking about your dog that you've named "My Ass".
just seems simpler to pronounce that "asterisk".
Yousuf Khan
Yousuf Khan
Jun 21, 2013, 12:16:51 AM6/21/13
to
On 17/06/2013 5:08 AM, Mike Dworetsky wrote:
> Dave Rove wrote:
>> Assuming that's how SGR A* is pronounced. It's as confusing in a
>> conversation as talking about your dog that you've named "My Ass".
>
> It's a very odd complaint. I can't see your point.
I think his complaint is about the word "star" in the name. Since we're
> Dave Rove wrote:
>> Assuming that's how SGR A* is pronounced. It's as confusing in a
>> conversation as talking about your dog that you've named "My Ass".
>
> It's a very odd complaint. I can't see your point.
talking astronomy here, the word "star" has a very specific meaning in
this field (i.e. a big ball of plasma undergoing nuclear fusion), so why
would they name this region of space with the word "star" in it, when
it's clearly something way more than any star. When you say the name out
loud, "Sagittarius A Star", it sounds like you're talking about a star,
like "Alpha Centauri B star", or "Sirius A star".
Yousuf Khan
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