Is Canopus really as powerful as Deneb?
jerry and judy
In a old astronomy book of mine (1976) Canopus is estimated at 36 parsecs,
making it one of the nearby bright stars, closer than Spica.
In one of my older star lists Canopus is listed as being 196 LYs distant.
With a -.73 apparent magnitude making it's absolute about -4.5
I purchased a newer book (1995) that places Canopus, with good reason I assume,
twice as far away as the Lower Centaurus-Crux OB Association at atleast
750 LYs!!
This would make Canopus, a very bright -7.5,
intrinsically brighter than Rigel -6.9
Is Canopus one of the 3-5 brightest stars visible to the human eye,
close to (maybe brighter than) Deneb -7.3, Wezen -7.1, Saiph -7.0,
Naos -7.0, Aludra -7.0 etc.?
Can anyone confirm this??
Erik Max Francis
jerry and judy wrote:
> This would make Canopus, a very bright -7.5,
> intrinsically brighter than Rigel -6.9
_Sky Catalogue 2000.0_ gives Canopus (F0 Ia) a distance of 360 pc, with
an absolute magnitude of -8.5.
> Is Canopus one of the 3-5 brightest stars visible to the human eye,
> close to (maybe brighter than) Deneb -7.3, Wezen -7.1, Saiph -7.0,
> Naos -7.0, Aludra -7.0 etc.?
>
> Can anyone confirm this??
This references gives the following spectral types, distances, and
absolute magnitudes for these stars:
Canopus F0 Ia 360 pc -8.5
Deneb A2 Ia 560 pc -7.5
Saiph B0.5 Ia 21 pc
Aludra B5 Ia 760 pc -7.0
I'm not familiar with a star named Naos, and the closest I could come to
"Wezen" was Wazn, which is a mere K2 III giant (absolute magnitude
-0.1).
--
Erik Max Francis, &tSftDotIotE / mailto:m...@alcyone.com
Alcyone Systems / http://www.alcyone.com/max/
San Jose, California, United States / icbm://+37.20.07/-121.53.38
\
"I've got the fever for the / flavor of a cracker"
/ Ice Cube
Sean Everington
Erik Max Francis wrote:
>
> jerry and judy wrote:
>
> > This would make Canopus, a very bright -7.5,
> > intrinsically brighter than Rigel -6.9
>
> _Sky Catalogue 2000.0_ gives Canopus (F0 Ia) a distance of 360 pc, with
> an absolute magnitude of -8.5.
>
> > Is Canopus one of the 3-5 brightest stars visible to the human eye,
> > close to (maybe brighter than) Deneb -7.3, Wezen -7.1, Saiph -7.0,
> > Naos -7.0, Aludra -7.0 etc.?
> >
> > Can anyone confirm this??
>
> This references gives the following spectral types, distances, and
> absolute magnitudes for these stars:
>
> Canopus F0 Ia 360 pc -8.5
> Deneb A2 Ia 560 pc -7.5
> Saiph B0.5 Ia 21 pc
> Aludra B5 Ia 760 pc -7.0
>
> I'm not familiar with a star named Naos,
Naos, is zeta puppis in the southern skies.
Sean :-)
Chris Marriott
In article <jerbidoc-210...@lc087.zianet.com>, jerry and judy
<jerb...@zianet.com> writes
>In a old astronomy book of mine (1976) Canopus is estimated at 36 parsecs,
>making it one of the nearby bright stars, closer than Spica.
>
>In one of my older star lists Canopus is listed as being 196 LYs distant.
>With a -.73 apparent magnitude making it's absolute about -4.5
>
>I purchased a newer book (1995) that places Canopus, with good reason I assume,
>twice as far away as the Lower Centaurus-Crux OB Association at atleast
>750 LYs!!
The most accurate source of star distances is the recently-published
Hipparcos catalog. This lists the parallax of Canopus as 0.01043",
corresponding to a distance of 95.87 parsecs, or 313 light years.
Chris
----------------------------------------------------------------
Chris Marriott, SkyMap Software, UK (ch...@skymap.com).
Visit our web site at: http://www.skymap.com
Astronomy software written by astronomers, for astronomers.
Erik Max Francis
Sean Everington wrote:
> Naos, is zeta puppis in the southern skies.
Ah, okay. In _Sky Catalogue 2000.0_, zeta Pup is listed as spectral
type O5.8, no luminosity class, and no distance or absolute magnitude
given.
Jedidiah Whitten
Erik Max Francis (m...@alcyone.com) wrote:
:
: Canopus F0 Ia 360 pc -8.5
: Deneb A2 Ia 560 pc -7.5
: Saiph B0.5 Ia 21 pc
: Aludra B5 Ia 760 pc -7.0
:
: "Wezen" was Wazn, which is a mere K2 III giant (absolute magnitude
: -0.1).
Wezen, or Wesen, is Delta Canis Majoris, which according to SC 2000.0 is F8Ia, absolute
magnitude -8.3, 700 pc (2300 ly) away.
--
Jedidiah Whitten (jswh...@ucdavis.edu)
+------------------------------------------+
| University of California, Davis |
| http://wwwcsif.cs.ucdavis.edu/~whitten |
| http://wwp.mirabilis.com/6569964 |
+------------------------------------------+
Bill J. Gray
Just last summer, the new Hipparcos results were published. These
provided (among other things) estimates for parallax (distance) data
roughly ten times more precise than any derived before (including the
Sky Catalog 2000 values given elsewhere in this thread.)
All the stars you mentioned were essentially in the "guesstimate"
zone. As you'll see, even Hipparcos hasn't completely reversed that
situation (Deneb has a distance uncertainty of about 2/3 of the total
value, leading to a pretty poorly-defined luminosity!), but it is
_far_ better than any other source. You'll notice that Deneb is still
the big boy on the block.
<shameless self-promotion ON:>
I fired up Guide 6.0, which uses Hipparcos and Tycho data as the
basis for brighter stars, and clicked for "more info" on these objects.
The results follow.
</shameless self-promotion OFF>
-- Bill
Canopus (Alpha Carinae):
Distance: 95.9 +/- 4.9 parsecs (313 +/- 16 light-years)
Luminosity: 13500 +/- 1400 times that of the sun
Absolute magnitude: -5.53 +/- 0.11
Deneb (Alpha Cygni):
Distance: 990 +/- 610 parsecs (3200 +/- 2000 light-years)
Luminosity: 260000 +/- 320000 times that of the sun
Absolute magnitude: -8.7 +/- 1.3
Wezen (Delta CMi):
Distance: 550 +/- 120 parsecs (1790 +/- 390 light-years)
Luminosity: 47000 +/- 20000 times that of the sun
Absolute magnitude: -6.87 +/- 0.48
Saiph (Kappa Orionis):
Distance: 221 +/- 33 parsecs (720 +/- 110 light-years)
Luminosity: 6000 +/- 1800 times that of the sun
Absolute magnitude: -4.65 +/- 0.32
Naos (Zeta Puppis):
Distance: 429 +/- 81 parsecs (1400 +/- 260 light-years)
Luminosity: 20000 +/- 7600 times that of the sun
Absolute magnitude: -5.95 +/- 0.41
Aludra (Eta Puppis):
Distance: 980 +/- 420 parsecs (3200 +/- 1400 light-years)
Luminosity: 84000 +/- 72000 times that of the sun
Absolute magnitude: -7.51 +/- 0.94
Erik Max Francis
Jedidiah Whitten wrote:
> Wezen, or Wesen, is Delta Canis Majoris, which according to SC 2000.0
> is F8Ia, absolute
> magnitude -8.3, 700 pc (2300 ly) away.
Are there different versions of the _Sky Catalogue 2000.0_? Mine lists
25 delta CMa as distance 940 pc, absolute magnitude -8.0.
Paul Schlyter
In article <6cq7qe$a9r$1...@noc1.gwi.net>, Bill J. Gray <pl...@gwi.net> wrote:
>Wezen (Delta CMi):
Make that Delta CMa
> Aludra (Eta Puppis):
> Distance: 980 +/- 420 parsecs (3200 +/- 1400 light-years)
> Luminosity: 84000 +/- 72000 times that of the sun
> Absolute magnitude: -7.51 +/- 0.94
There is no star Eta Puppis. When Argo Navis got subdivided into
Carina, Vela and Puppis, the star Eta Argus fell into the subdivision
Carina, thus there is today an Eta Carinae (a quite well-known
variable star BTW), but neither an Eta Velorum nor an Eta Puppis.
On the other hand, the star with the proper name "Aludra" is really
Eta Canis Majoris, and Canis Major happens to be in the vicinty of
Puppis.
--
----------------------------------------------------------------
Paul Schlyter, Swedish Amateur Astronomer's Society (SAAF)
Grev Turegatan 40, S-114 38 Stockholm, SWEDEN
e-mail: pau...@saaf.se paul.s...@ausys.se pa...@inorbit.com
WWW: http://spitfire.ausys.se/psr -- updated daily!
Bill J. Gray
Hi Paul,
"Make (Wezen) Delta CMa..."
"There is no star Eta Puppis..."
I goofed here! They are indeed both in Canis Major. The remaining
data for both stars are correct... I got the right stars and the wrong
constellations. Dunno how I managed to do that, though.
-- Bill
Michael Dworetsky
Chris Marriott wrote:
>
> >In a old astronomy book of mine (1976) Canopus is estimated at 36 parsecs,
> >making it one of the nearby bright stars, closer than Spica.
> >
> >In one of my older star lists Canopus is listed as being 196 LYs distant.
> >With a -.73 apparent magnitude making it's absolute about -4.5
> >
> >I purchased a newer book (1995) that places Canopus, with good reason I assume,
> >twice as far away as the Lower Centaurus-Crux OB Association at atleast
> >750 LYs!!
>
> The most accurate source of star distances is the recently-published
> Hipparcos catalog. This lists the parallax of Canopus as 0.01043",
> corresponding to a distance of 95.87 parsecs, or 313 light years.
>
> Chris
In that case, M(V) = -5.7 (doing this in my head to nearest 0.1 mag)
which is consistent with class F0 Ib. A class F0 Ia star would be
around 2 or 3 mag more luminous.
-
Mike Dworetsky, Department of Physics
& Astronomy, University College London
Gower Street, London WC1E 6BT UK
email: m...@star.ucl.ac.uk
Peter Munn
In sci.astro I read Chris Marriott's message of Sun, 22 Feb 1998
> jerry and judy <jerb...@zianet.com> write
>>In a old astronomy book of mine (1976) Canopus is estimated at 36
>>parsecs,
..
>>In one of my older star lists .. 196 LYs distant.
..
>>I purchased a newer book (1995) .. at least 750 LYs!!
>
>The most accurate source of star distances is the recently-published
>Hipparcos catalog. This lists the parallax of Canopus as 0.01043",
>corresponding to a distance of 95.87 parsecs, or 313 light years.
Why *was* there so much uncertainty about the distance of Canopus until
relatively recently? This has often intrigued me. What were the
difficulties?
--
Peter Munn
Software Designer
Staffordshire UK
Paul Schlyter
In article <i9VhxNAn...@pearce-neptune.demon.co.uk>,
accurately before Hipparcos. Various indirect methods if distance
measurements failed too, because Canopus is not a known double
star, it's not a member of a star cluster, it's not a Cepheid,
among other things.
Gunnar Ljungstrand
Bill J. Gray wrote:
> [snip]
>
> Deneb (Alpha Cygni):
> Distance: 990 +/- 610 parsecs (3200 +/- 2000 light-years)
> Luminosity: 260000 +/- 320000 times that of the sun
> Absolute magnitude: -8.7 +/- 1.3
>
> [snip]
Hmm... Deneb max luminosity: 260000 + 320000 = 580000 times the sun.
Okay. Min luminosity: 260000 - 320000 = -60000 times the sun...!!!
:-) Funny... I´ve never seen negative luminosity before. :-)
/Gunnar
Bill J. Gray
Hi Gunnar,
Yeah, I noticed that, too; it's pretty common for the uncertainty
in the distance (or luminosity) to exceed the actual value given. In
such a case, about all you're learning is that "this number is _really_
just a guess."
In the case of Deneb, we're being told that the parallax is about
1 milliarcsecond, plus or minus about .6 milliarcseconds. And this
is a mild case. Occasionally, the measured parallax (and, therefore,
distance) is _negative_. Which simply means the random errors in the
observations piled up in the "wrong" direction... it happens quite
often in the Tycho catalog.
-- Bill
dud...@msn.com
Hi,
My first posting here (hope it works). Anyhow, I thought it would be
interesting to take data from Hipparcos as is (ignoring error bars is
unscientific, I know), and find the brightest absolute magnitudes of all the
stars with at least 1 milliarcsecond parallax (i.e. within 3260 ly). This is
the top thirty.
1. -8.7 Alp Cyg (Deneb)
2. -7.5 Eta CMa (Aludra)
3. -6.9 Del CMa (Al Wazor)
4. -6.7 Bet Ori (Rigel)
5. -6.4 Omi2CMa
6. -6.4 Eps Ori (Alnilam)
7. -6.1 HD 74180 Vel
8. -6.1 Gam Cyg (Sadr)
9. -6.0 Zet Pup (Naos)
10. -5.9 Eps Aur
11. -5.7 Iot1Sco
12. -5.6 Eta Leo
13. -5.6 Tau CMa
14. -5.6 Ups Car
15. -5.5 Alp Car (Canopus) (so the answer to the thread looks like - no)
16. -5.5 Iot CMa
17. -5.4 Bet Cen (Hadar)
18. -5.4 Alp Lep (Arneb)
19. -5.3 Phi Vel
20. -5.3 Gam2Vel
21. -5.3 Iot Ori
22. -5.3 Alp Sco (Antares)
23. -5.3 Zet Ori (Alnitak A)
24. -5.1 Alp Ori (Betelgeuse)
25. -5.1 HD 59612 Pup
26. -5.0 Lam Sco (Shaula)
27. -5.0 Omi1CMa
28. -5.0 Omi Pup
29. -5.0 Del Ori (Mintaka A)
30. -5.0 45 Dra
What is interesting here, in my view, is how many of these stars are in the
same area of the sky centered on Canis Major and extending to Orion in one
direction and Vela and Puppis in the other. These three neighboring
constellations account for more than half the top thirty. Why is this? Note
that Sirius (Alp CMa) with an absolute mag of 1.46 doesn't even come close to
making this list, and is only coincidentally in the same direction as these
absolutely more luminous distant stars. Anyway I'll look at Canis Major with
a lot more respect from now on.
Jim
-----== Posted via Deja News, The Leader in Internet Discussion ==-----
http://www.dejanews.com/ Now offering spam-free web-based newsreading
jerry and judy
look toward Canopus/Vela etc. we're looking along this *edge*. But as we
look toward Orion/CMa, this direction is just above the head-on Arm and on
outward from the center of the galaxy. As we continue along the Arm
through Aur/Cyg we can stop at Aquila, at which point we'll be looking
down the *edge* of the Arm in the opposite direction from Car/Vel. In the
early days of mapping the Galaxy, it was believed that our Local Arm
stretched from Cygnus to Orion, instead of Vela. As a result, some
astronomers suggested that our Local Arm should be demoted to the ~Orion
Spur", signifying a mere appendage of the Perseus Arm. But the most recent
surveys of molecular clouds in Cygnus and Vela show that the Orion Arm is
in fact every bit as massive as the Perseus Arm ( if not as extensive
lengthwise).
If we were flying into the Galaxy from the outside, our attention would
hardly be drawn by the dark clouds of Cygnus and Vela or the extended
star-associations of Scorpius. We would notice the brilliant bright stars
and protostars of Orion, among the youngest and brightest stars to have
formed in our part of the Galaxy where the Sun currently lies.
Thanks for the list!
jerry and judy
> Hi,
> My first posting here (hope it works). Anyhow, I thought it would be
> interesting to take data from Hipparcos as is (ignoring error bars is
Where did you get your Hipparcos data, is it still $500 or so?
I get the feeling that if I have to ask how much it is, I can't afford it
for personal use.
The latest info I have is
The Hipparcos and Tycho data are now available both for browsing and for
ftp downloading at the CDS-Strasbourg:
Using the catalogue server "Astronomer's Bazaar" or the "VizieR" look-up
service, ask for catalogue I/239.
\Brian Skiff (b...@lowell.edu)
Is there a less expensive (smaller) edition than what's avbl here?
http://astro.estec.esa.nl/SA-general/Projects/Hipparcos/catalog.htm
Thanks!
Michael Dworetsky
dud...@msn.com wrote:
>
> Hi,
> My first posting here (hope it works). Anyhow, I thought it would be
> interesting to take data from Hipparcos as is (ignoring error bars is
[snip]
The most luminous stars in our galaxy (the supergiant stars) are
comparatively young and all lie near the Milky Way plane. In the
direction of CMa, Ori, Vel, Pup you are looking outwards away from the
galactic centre. There is a lot less dust in the plane in that
direction than if you look towards the central region (or within +/- 90
degrees of it, like Cygnus). Thus, you see to greater distances for a
given absolute magnitude. You seem to have selected only the apparently
brighter stars in your sample. There are very luminous stars in the
other direction, but they are a lot fainter than the ones you quote
because there is more dust in the way, so they probably would not make
your list.
--
dud...@msn.com
In article <jerbidoc-250...@lc056.zianet.com>,
jerb...@zianet.com (jerry and judy) wrote:
>
> Where did you get your Hipparcos data, is it still $500 or so?
>
> I get the feeling that if I have to ask how much it is, I can't afford it
> for personal use.
>
> The latest info I have is
>
> The Hipparcos and Tycho data are now available both for browsing and
for
> ftp downloading at the CDS-Strasbourg:
>
> http://cdsweb.u-strasbg.fr
>
> Using the catalogue server "Astronomer's Bazaar" or the "VizieR" look-up
> service, ask for catalogue I/239.
Hi there, the above link is correct. When you get there hit the VizieR link
at the top. Then you can type in "Hipparcos" as a key word, and you will find
the Hipparcos and Tycho catalog. VizieR lets you generate a table and sort it
for instance by parallax or visual magnitude. This table is limited to 10000
stars, I think, and I only downloaded what I was interested in such as all
the stars with parallax greater than 30 mas, i.e. less than 100 ly or so, as
one download, and all stars with magnitude less than 6.9 was another. It may
take a few minutes to get the table and then to download it. It comes as a
hypertext file, but this can be saved as plain text on your computer. Then,
you can write programs to read this data and manipulate it as I did. Good
luck. VizieR is reasonably straightforward, but takes a few tries to figure
out,
Chris Marriott
In article <jerbidoc-250...@lc056.zianet.com>, jerry and judy
<jerb...@zianet.com> writes
>Where did you get your Hipparcos data, is it still $500 or so?
ESA sell volume 1 and volume 17 of the Hipparcos catalog for about £60
($100 or so). Vol 17 is a book containing 6 CD-ROMs with the complete
mission results. Vol 1 is a VERY nice book containing full details of
the contents of the catalog CD-ROMs, how the data was processed, and all
sorts of other interesting stuff.
Details are on the ESA web site.
jerry and judy
In article <34F38C79...@alcyone.com>, Erik Max Francis
<m...@alcyone.com> wrote:
> AndersonRM wrote:
>
> > Cygnus OB2 No. 12, absolute visual magnitude of -9.9.
> > Guiness Book of Records, 1995. :)
>
> Uh, yeah? And?
>
> --
> Erik Max Francis, &tSftDotIotE / mailto:m...@alcyone.com
>
I can't find the Cygnus OB2 Association.
I can find Cygnus OB4, Lacerta OB1 and Cepheus OB2
all within 500LYs of Deneb.
Cygnus OB4 and OB9 are twice as far away, would it be out that far?
How are these star assocations numbered, by brightness, distance or
chronological?
Thomas Womack
In sci.astro jerry and judy <jerb...@zianet.com> wrote:
: Where did you get your Hipparcos data, is it still $500 or so?
: I get the feeling that if I have to ask how much it is, I can't afford it
: for personal use.
Downloading it is free - unfortunately, it's quite a large file.
ftp://cdsweb.u-strasbg.fr/pub/cats/I/239/hip_main.dat (50.8M)
http://cdsweb.u-strasbg.fr/ has a link to the file
The server is not very fast; if you'd prefer, you can get it from
http://mc64.merton.ox.ac.uk/hipparcos.dat, which might be a bit
quicker. It'll be there until this time next week, when I go home
and take that server with me.
Tom
Steve Willner
> : Where did you get your Hipparcos data, is it still $500 or so?
> : I get the feeling that if I have to ask how much it is, I can't afford it
> : for personal use.
Check the Hipparcos home page:
http://astro.estec.esa.nl/SA-general/Projects/Hipparcos/hipparcos.html
There was going to be a CD with all the data in binary form and some
programs to use them for about $50, but I don't see it on the order
form now. You can get an ASCII CDROM set for $100.
Downloads are possible but slow. Downloading an interesting subset
may be more practical.
--
Steve Willner Phone 617-495-7123 swil...@cfa.harvard.edu
Cambridge, MA 02138 USA
(Please email your reply if you want to be sure I see it; include a
valid Reply-To address to receive an acknowledgement. Commercial
email is NOT appreciated.)
Paul Schlyter
In article <35070...@cfanews.harvard.edu>,
Steve Willner <wil...@cfa183.harvard.edu> wrote:
>> : Where did you get your Hipparcos data, is it still $500 or so?
>> : I get the feeling that if I have to ask how much it is, I can't afford it
>> : for personal use.
>
>Check the Hipparcos home page:
>http://astro.estec.esa.nl/SA-general/Projects/Hipparcos/hipparcos.html
>
>There was going to be a CD with all the data in binary form and some
>programs to use them for about $50, but I don't see it on the order
>form now. You can get an ASCII CDROM set for $100.
>
>Downloads are possible but slow. Downloading an interesting subset
>may be more practical.
You could get the "Guide 6" CD-ROM instead, then you'll get the Hipparcos
catalog + many other catalogs in binary form, including information of
the storage formats of these binaries, so you can access them also from
your own software. Check out http://www.projectpluto.com