May 26, 2024 • 21 mins
Join Jordan & Kit as they explore the amazing astronomy and other cosmic background of the constellation Perseus!
Episode transcripts: https://www.starrytimepodcast.com/episode-transcripts.html
Timestamps
00:00:00 Intro
00:03:25 Initial Impressions and How to Find this Constellation
00:05:53 Brightest Star
00:09:36 Bayer's Variable Star
00:15:09 Gold Star
00:21:09 Outro
Mark as Played
Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
>> Jordan (00:16):
Hi, I'm Jordan.
>> Kit (00:17):
And I'm Kit.
>> Jordan (00:19):
Welcome to Starry Time, where stars plus
lines
>> Kit (00:23):
equal stories.
>> Jordan (00:24):
For this month, we'll be exploring the constellation
Perseus. You know, the ancient Greek
quote hero.
>> Kit (00:31):
Yes, just Perseus. Another one like
Hercules. Uh, so in this episode, we're going to
talk about the astronomy and other cosmic background
of this constellation. If you listened to our
episodes on Cassiopeia, Cepheus
and or Andromeda earlier this
season, it should come as no surprise to
you that Perseus is another of the
(00:53):
48 great
>> Jordan (00:55):
great great great great great great great great great great great great
>> Kit (01:05):
Constellations identified by
Ptolemy in his second century
Almagest. And, uh, this should be
no surprise because Perseus is also part of
that entire saga.
>> Jordan (01:17):
And it is quite a saga indeed. We
needed several months away from that myth verse,
to be honest, before we could really return to
talk about Perseus. But we'll save those thoughts
for next week's myths and retcons episode.
>> Kit (01:33):
Yeah, and, uh, Perseus also has some other
notable myths that we will roll into that
episode next week.
>> Jordan (01:40):
Lot going on with our guy.
Perseus. Speaking of the constellation
we call Perseus was sometimes called
Perseus and the head of Medusa. And
the constellation was illustrated with Perseus
holding the Gorgon's head. But the
IAU doesn't use this name,
does not allow Perseus to accessorize
(02:02):
with the dead skull of his
victim. And it didn't really catch
on. So we will just refer to it as Perseus for this
month.
>> Kit (02:12):
Yeah, it's probably for the best. And, you
know, I sort of wish that Perseus didn't catch
on, but, you know, I, um, think this should just be a
Maenad constellation.
>> Jordan (02:22):
I mean, my retconstellation might be Medusa
holding up the head of Perseus but when we
take over the IAU, I'm sure we'll, you know, make
sure a lot of changes that we see fit are finally
made.
>> Kit (02:34):
All right. I will hold off on my Perseus character
gripes much like I did when we got to the
Orion myth gripes. Um, yeah,
it's not, it's not, uh, I think the problem is, like, I'm
not as attached to this constellation as I
am attached to the constellation Orion. And so all I
can think about is Perseus the quote unquote
(02:55):
hero. And I really need to let that go so we can
really get into the astronomy of this constellation
>> Jordan (03:01):
Kit, to be fair, we all do have our
biases. However, this
constellation is actually
larger than Orion. It is the
24th of the IAU recognized
constellations compared with Orion's
26th ranking.
>> Kit (03:18):
So perhaps the difference isn't in the
size so much as the findability in the night
sky.
So before we get technical about it, what does this
constellation look like to you, Jordan?
>> Jordan (03:31):
Based on the pictures I saw, this one was pretty
representational. It actually looked vaguely
like a, uh, stick figure or
vaguely like half of a stick figure at
least. It also reminded me of the ancient
Greek letter lambda. But, yeah, this
one I wouldn't say was super complex, but
(03:51):
I can see how it could become a person. How
about you? What do you see here, Kit?
>> Kit (03:56):
Yeah, same. So I kind of see like this one leg,
stick figure figure with a tiny little
hat and flailing arms. So, yeah,
something definitely human like here.
Yeah, I begrudgingly will admit that there's something
human like, but, you know, it's not as tidy
and clear as the three stars of Orion's
(04:17):
belt and the head and the two feet and the arms.
But, you know.
>> Jordan (04:21):
I'm glad that you also saw the or imagined
the flailing arms. That definitely
stuck out to me. Maybe that's just the Perseus we
want to see. Just arms failing, toppling
over down the stairs. But yes, as we
mentioned earlier, Orion is a lot to live up
to. And you're right, Perseus doesn't have a
(04:42):
lot of super bright stars to find.
Perhaps the easiest way is to go
first to his mother in law,
Cassiopeia.
>> Kit (04:53):
Right. The constellation Cassiopeia is a
vaguely W or M shape in the night
sky. Very, I think, noticeable. If
Cassiopeia's up there looking like a W, then you'll
find Perseus below and to the left. If she looking like
an M, then Perseus will be to the lower right. If you
follow one of the center stars of Cassiopeia.
>> Jordan (05:13):
And its other neighboring constellations we've discussed
on the pod before, including Aries
and Taurus to the south and
Auriga
>> Kit (05:22):
AURIGAAA
>> Jordan (05:25):
to the east and Andromeda to the
West.
>> Kit (05:29):
And if all that doesn't help, it has a right
ascension of about 4 hours and a declination of
40 degrees north.
>> Jordan (05:36):
If you live above positive 40 degrees
latitude, this constellation never sets
below the horizon, but otherwise you can see
it high in the night sky in the rest of the northern
hemisphere and in parts of the southern
hemisphere in November.
>> Kit (05:52):
So now that we know what it looks like and where
to find it, let's talk about the brightest star
in the constellation.
>> Jordan (06:00):
Kit, I have excellent
news.
>> Kit (06:03):
Okay
>> Jordan (06:05):
Our favorite late
16th century astronomer
slash lawyer Johann
Bayer absolutely
crushed this assignment,
knocked it out of the park. Designating the
brightest star in this constellation
as Alpha
(06:27):
Persei, which is better known by
its formal name of Mirfak.
>> Kit (06:33):
Oh, uh, I'm so proud of our guy. I mean,
really, it's so hard to be a late
16th century astronomer slash lawyer. You had to have so
many jobs. I mean, wow.
>> Jordan (06:44):
Bayer, we never doubted you. So, the
formal name Mirfak comes from an
Arabic phrase meaning elbow.
It is a yellow white supergiant
star with an apparent magnitude of
positive 1.81. And it's
located about 510
light years from Earth. It is
(07:07):
more massive, larger, and
more luminous than our sun by, like,
a lot. Like. Like, a lot. A lot.
For example, it has 68
times the radius of our sun,
and it is 8.5
times the mass of our sun.
>> Kit (07:26):
Yeah, that's big. So remember that the
radius of our sun is about
432,000
miles, which is 109
times the radius of the Earth. So this is
a big star. It's likely
evolved right, um, on that main sequence, and
it's probably gonna be ready for a collapse sometime
(07:49):
soon.
>> Jordan (07:50):
Back in 2010, astronomers published a paper
suggesting the star might have a gas giant
about six times the mass of Jupiter
orbiting this star. But this hasn't yet been
confirmed, and there is some evidence to suggest
the initial findings might have been
incorrect or a star spot
or another artifact in the data.
>> Kit (08:11):
Yeah, I guess we're going to need some more research on this star
to learn more.
>> Jordan (08:15):
Perhaps it's there, perhaps it's not. One
other interesting thing I've learned about this star is that it is
the only star in Perseus that's
considered a navigational star.
>> Kit (08:26):
Oh, yeah. I don't think we've talked about navigational
stars on the pod before. Maybe we want to
do a quick snapshot on them and loop back on it some
other time, but just maybe a short picture of what a, uh,
navigational star is?
>> Jordan (08:39):
Kit, of course. And there are 58
special celestial navigation stars
in the night sky. Well, technically,
there's 57 and
Polaris, but these stars are used
to navigate by seafarers, especially since
on the sea, all you got is ocean.
(09:00):
Ocean. And if you look around, Kit,
you wouldn't believe me, but more ocean.
So if your satellites go down, or
perhaps you're trying to navigate by sea before we even
had satellites, perish the thought, and you want to
ensure you're going the right way, you could use these
very special stars to help guide your
(09:21):
ship.
>> Kit (09:22):
Yeah, very cool. Uh, and you know, there is celestial
navigation when you are, you know, wandering
around in other places, but it's pretty clear why you might
need stars since there is no landscape
to look at, uh, when you're on the ocean.
>> Jordan (09:35):
Let's move into our next segment, which is
Bayer's variable star. Here we
follow the Greek alphabet to learn more about the
Bayer designated stars in the night
sky. Last month, I swerved a little bit
and tried to find something a little bit more
interesting. No respect to Nu
Lyrae, but where did you go with this one,
(09:57):
Kit? Did you follow the alphabet and the
assignment, or were you
swept away by some other star of interest?
>> Kit (10:06):
Well, I'm famously only a
rule bender, not a rule breaker,
so I'm gonna do a little like. Yesa and
here.
>> Jordan (10:16):
Kit, you're almost the
avatar of rule bending.
>> Kit (10:20):
Thank you. Okay, so first things first.
Let's talk about Xi
persei, which is. It's spelled
sort of like, or it's transliterated as xi,
but it's pronounced, I think, K-See or
K-Sai something like this. It's Greek so I
don't know. It's a Greek letter. Um, this would come after
(10:40):
Nu in the Greek alphabet. Um, and this star also
has the name Menkib, which is
derived from an Arabic word meaning shoulder.
It has an apparent magnitude of positive
4.06, and it is an O type
blue giant star.
>> Jordan (10:56):
Since it is a blue giant, it's gotta be
pretty bright, right? So it's got to be far away
if the apparent magnitude is so high.
>> Kit (11:04):
Mm mhm hmm. Absolutely. So its
absolute luminosity is way,
way, way brighter than our sun.
And the star itself is 30 solar masses.
So it's huge and it's very bright and
luminous. But it's 1200 light years
away, so. So it's quite far
away. Exactly. Um, this star
(11:27):
is also a suspected runaway star,
and its radiation is part of the
reason why the Californa nebula, which is located
in Perseus seems to be glowing. If you've ever seen
a picture of that nebula.
>> Jordan (11:41):
All right, Xi Persei.
I don't know how to say you either, but pretty
cool.
>> Kit (11:47):
Yeah. So there was actually something kind of interesting about it.
So I wanted to, uh, wanted to make sure we got back on
track, but I also
really feel it's necessary that we do a quick shout
out to Beta Persei.
>> Jordan (12:00):
Kit. That is why you are avatar,
the last rule, bender.
>> Kit (12:06):
Well, I have to, because Beta
Persei is probably the most
famous star in this constellation.
It's also called Algol, which is
derived, again, from an Arabic phrase meaning the
head of the ghoul or the head of the
ogre. And this star is,
um, considered unlucky. It's known as the
(12:27):
demon star. It's known as Satan's
head. So, yeah.
>> Jordan (12:32):
Wow, that's quite an escalation. We started
from elbows and shoulders, but you keep making
your way up to the head and stuff starts getting
really real here.
>> Kit (12:41):
Yeah. So in the ancient Greek mythos,
this star is symbolizing that head of Medusa
that we mentioned earlier. And it, in
reality is actually, um, a three star
system. So it's been confirmed to have three,
um, stars. There might be some additional
companions, maybe even a five star system, or there
(13:01):
might be some, you know, optical binaries.
Um, and the main star
is, in fact, an actual variable
star.
>> Jordan (13:11):
Which means its brightness as perceived
from Earth, aka its apparent
magnitude, changes over time,
usually in a set interval or
within a relatively short period of
time. So this isn't something like a
supernova or a nova, where it brightens
temporarily and then fades.
>> Kit (13:32):
Exactly. So it sort of has this brightening and
dimming effect that happens over time. And this
variable brightness in Beta Persei
is caused by the orbits of the stars, which
cause them to eclipse one another at
these regular intervals. So
every three days or so, um, one
of the pairs, which is an eclipsing
(13:54):
binary pair, orbits each other, they eclipse
each other, and this pair is
0.062
au from each other.
>> Jordan (14:04):
Kit, that is very, very close.
>> Kit (14:07):
Uh-huh.
>> Jordan (14:08):
Let's remember that one AU
is about the distance from the Earth to the
sun. Though in 2012, the
IAU made a more specific redefinition.
>> Kit (14:19):
Yep, absolutely. So there's a slightly more technical
definition, but in general, we're talking about, you know,
much, much, much smaller,
these stars, right, orbiting one another very
closely. Um, and there are some really cool
visualizations of this system, so I
will be sure to post those over on our socials
(14:39):
at starrytimepod on the Universeodon Mastodon
server, and of course, over on Twitter.
>> Jordan (14:45):
Kit, I can't thank you enough for
getting Bayer's Variable Star back on track.
Let's take a quick break, and then we'll come back to find
out about my pick for gold star
of the month.
>> Kit (15:07):
Welcome back. This segment is called Gold
Star. In this segment, we alternate
picking the star or space object in our
constellation of the month that captures our
minds, our hearts,
and our very souls. So,
Jordan, what was your pick this month for gold star?
>> Jordan (15:28):
Well, Kit, there was a fair amount to choose
from this month in Perseus but
as soon as I read about this one particular
deep sky object, my decision was
made for me.
>> Kit (15:40):
Yeah, this part of the night sky is really
interesting because it does align with the galactic
plane of the Milky Way, but there's a
lot of sort of molecular clouds that are hiding and
obscuring the usual stuff that we see in this part of
the night sky and that we can sort of see on the galactic
plane.
>> Jordan (15:58):
Yes, Kit. Exactly. And one of
the major things in this constellation
is the Perseus cluster, which is
also known as Abell, or
Abell 426. And it's one
of the closest galaxy clusters to earth
at about
76.6
(16:19):
million light years away.
>> Kit (16:21):
You know, just a veritable hop and a skip away.
>> Jordan (16:24):
You know, Kit, it's all relative. It is one of the
closest. But what really captivated my
heart was the giant elliptical
galaxy at the center of this cluster
called NGC
1275, also known
as Perseus A, or
Caldwell 24.
>> Kit (16:45):
And these names are all so exciting and so
captivating.
>> Jordan (16:50):
Yeah, you instantly remember them. NGC.
What was the number again?
NGC 1275.
And Cornwell? No, Caldwell
24. This galaxy is a
Seyfert galaxy, which, at visible
spectrum, look like regular old
galaxies, but they have
(17:11):
extremely bright active
nuclei. And such active galaxies,
as they are called, are designed as
active galactic
nucleuses, or AGN's.
>> Kit (17:23):
Yep, and you're right. So we can
see these AGN's, these really active, bright
nuclei outside of the visible spectrum, so things
like radio and x ray, and this is important, The
Milky Way, our home galaxy, is
not an AGN
>> Jordan (17:40):
Kit, unfortunately, you are correct.
Our Milky Way, whatever it has going for
it does not have active
galactic nucleus status, because
these AGN galaxies have
supermassive black holes that are
actively accreting matter.
NGC
(18:00):
1275, as a Seyfert
galaxy, has a quasar like center.
NGC 1275 is
special since these Seyfert galaxies
only account for about
10% of all the galaxies that we
found
>> Kit (18:18):
So, rare and very active. Right. And
this idea that, you know, we in the Milky Way, we do
have a supermassive black hole at our center, but it's not accreting
matter. So. Okay, I'm still with you.
>> Jordan (18:29):
Kit, yes, this is a rare and
active galaxy. So pretty special to
me.
>> Kit (18:35):
Mhm.
>> Jordan (18:35):
And what stood out to me about it, in addition
to that, is that there's these super
elaborate filaments that surround the
galaxy. And these filaments, well,
essentially they're cool gas that's
been surrounded by super, very hot
interstellar gas. And now
here's where things get even more interesting.
(18:58):
This cooler gas is basically
deposited from the center of the galaxy
by radio bubbles.
>> Kit (19:06):
A radio bubble.
>> Jordan (19:09):
Radio bubbles.
>> Kit (19:11):
What?
>> Jordan (19:12):
Yes. So good.
Basically, bubbles of
relativistic plasma rise
out of that active nucleus and into the
surrounding hot, hot
gas and somehow have remained in
place instead of, you know, warming up
or collapsing into stars. Because of
(19:33):
this, some astronomers have hypothesized
that the magnetic field around these filaments
is keeping them intact.
>> Kit (19:41):
Oh, that is so interesting. Right. We have this, like, really
weird dynamic around it where it's like, yeah,
what? How are these cool parts of gas? Like, how
is this gas like this? Like, how is it here? That's
cool.
>> Jordan (19:53):
Two more things here, Kit. First, these
bubbles create sound waves, which
apparently sound like a b flat,
approximately 57 or
so octaves below middle C.
>> Kit (20:07):
Oh, my god. First of all, that is so low and
also so specific. Right? Like,
some astronomer was able to figure this
out. That's amazing. You can, like, hear
radio bubbles. That's. That's, like. Yeah, it's a little bit mind
boggling.
>> Jordan (20:22):
Kit, let me send you the link to put on our
socials, for sure. There's an excellent New York
Times article. Add it to your mixtape. And
finally, we've also observed
two supernovae in
NGC 1275. As
if we needed any other reason to give this
extremely cool space object the gold
(20:44):
star of the month award.
>> Kit (20:46):
What a great choice. This is a new galaxy
type for the pod, complete with a supermassive
black hole, my first love, mysterious
and beautiful filaments. Uh, a music
of its own. And supernovae.
Welcome to the Gold Star Club
NGC
1275.
>> Jordan (21:14):
That brings us to the end of our exploration
of the cosmic background of our
constellation Perseus. Next
week, we will be retelling and
reconstellationing the myths of this
constellation.
>> Kit (21:27):
This has been Kit
>> Jordan (21:29):
And Jordan.
>> Kit (21:30):
Sisters, lovers of stars and stories.
>> Jordan (21:33):
And we'll see you next time
>> Kit (21:35):
On Starry Time.
Hi, I'm Jordan.
>> Kit (00:17):
And I'm Kit.
>> Jordan (00:19):
Welcome to Starry Time, where stars plus
lines
>> Kit (00:23):
equal stories.
>> Jordan (00:24):
For this month, we'll be exploring the constellation
Perseus. You know, the ancient Greek
quote hero.
>> Kit (00:31):
Yes, just Perseus. Another one like
Hercules. Uh, so in this episode, we're going to
talk about the astronomy and other cosmic background
of this constellation. If you listened to our
episodes on Cassiopeia, Cepheus
and or Andromeda earlier this
season, it should come as no surprise to
you that Perseus is another of the
(00:53):
48 great
>> Jordan (00:55):
great great great great great great great great great great great great
>> Kit (01:05):
Constellations identified by
Ptolemy in his second century
Almagest. And, uh, this should be
no surprise because Perseus is also part of
that entire saga.
>> Jordan (01:17):
And it is quite a saga indeed. We
needed several months away from that myth verse,
to be honest, before we could really return to
talk about Perseus. But we'll save those thoughts
for next week's myths and retcons episode.
>> Kit (01:33):
Yeah, and, uh, Perseus also has some other
notable myths that we will roll into that
episode next week.
>> Jordan (01:40):
Lot going on with our guy.
Perseus. Speaking of the constellation
we call Perseus was sometimes called
Perseus and the head of Medusa. And
the constellation was illustrated with Perseus
holding the Gorgon's head. But the
IAU doesn't use this name,
does not allow Perseus to accessorize
(02:02):
with the dead skull of his
victim. And it didn't really catch
on. So we will just refer to it as Perseus for this
month.
>> Kit (02:12):
Yeah, it's probably for the best. And, you
know, I sort of wish that Perseus didn't catch
on, but, you know, I, um, think this should just be a
Maenad constellation.
>> Jordan (02:22):
I mean, my retconstellation might be Medusa
holding up the head of Perseus but when we
take over the IAU, I'm sure we'll, you know, make
sure a lot of changes that we see fit are finally
made.
>> Kit (02:34):
All right. I will hold off on my Perseus character
gripes much like I did when we got to the
Orion myth gripes. Um, yeah,
it's not, it's not, uh, I think the problem is, like, I'm
not as attached to this constellation as I
am attached to the constellation Orion. And so all I
can think about is Perseus the quote unquote
(02:55):
hero. And I really need to let that go so we can
really get into the astronomy of this constellation
>> Jordan (03:01):
Kit, to be fair, we all do have our
biases. However, this
constellation is actually
larger than Orion. It is the
24th of the IAU recognized
constellations compared with Orion's
26th ranking.
>> Kit (03:18):
So perhaps the difference isn't in the
size so much as the findability in the night
sky.
So before we get technical about it, what does this
constellation look like to you, Jordan?
>> Jordan (03:31):
Based on the pictures I saw, this one was pretty
representational. It actually looked vaguely
like a, uh, stick figure or
vaguely like half of a stick figure at
least. It also reminded me of the ancient
Greek letter lambda. But, yeah, this
one I wouldn't say was super complex, but
(03:51):
I can see how it could become a person. How
about you? What do you see here, Kit?
>> Kit (03:56):
Yeah, same. So I kind of see like this one leg,
stick figure figure with a tiny little
hat and flailing arms. So, yeah,
something definitely human like here.
Yeah, I begrudgingly will admit that there's something
human like, but, you know, it's not as tidy
and clear as the three stars of Orion's
(04:17):
belt and the head and the two feet and the arms.
But, you know.
>> Jordan (04:21):
I'm glad that you also saw the or imagined
the flailing arms. That definitely
stuck out to me. Maybe that's just the Perseus we
want to see. Just arms failing, toppling
over down the stairs. But yes, as we
mentioned earlier, Orion is a lot to live up
to. And you're right, Perseus doesn't have a
(04:42):
lot of super bright stars to find.
Perhaps the easiest way is to go
first to his mother in law,
Cassiopeia.
>> Kit (04:53):
Right. The constellation Cassiopeia is a
vaguely W or M shape in the night
sky. Very, I think, noticeable. If
Cassiopeia's up there looking like a W, then you'll
find Perseus below and to the left. If she looking like
an M, then Perseus will be to the lower right. If you
follow one of the center stars of Cassiopeia.
>> Jordan (05:13):
And its other neighboring constellations we've discussed
on the pod before, including Aries
and Taurus to the south and
Auriga
>> Kit (05:22):
AURIGAAA
>> Jordan (05:25):
to the east and Andromeda to the
West.
>> Kit (05:29):
And if all that doesn't help, it has a right
ascension of about 4 hours and a declination of
40 degrees north.
>> Jordan (05:36):
If you live above positive 40 degrees
latitude, this constellation never sets
below the horizon, but otherwise you can see
it high in the night sky in the rest of the northern
hemisphere and in parts of the southern
hemisphere in November.
>> Kit (05:52):
So now that we know what it looks like and where
to find it, let's talk about the brightest star
in the constellation.
>> Jordan (06:00):
Kit, I have excellent
news.
>> Kit (06:03):
Okay
>> Jordan (06:05):
Our favorite late
16th century astronomer
slash lawyer Johann
Bayer absolutely
crushed this assignment,
knocked it out of the park. Designating the
brightest star in this constellation
as Alpha
(06:27):
Persei, which is better known by
its formal name of Mirfak.
>> Kit (06:33):
Oh, uh, I'm so proud of our guy. I mean,
really, it's so hard to be a late
16th century astronomer slash lawyer. You had to have so
many jobs. I mean, wow.
>> Jordan (06:44):
Bayer, we never doubted you. So, the
formal name Mirfak comes from an
Arabic phrase meaning elbow.
It is a yellow white supergiant
star with an apparent magnitude of
positive 1.81. And it's
located about 510
light years from Earth. It is
(07:07):
more massive, larger, and
more luminous than our sun by, like,
a lot. Like. Like, a lot. A lot.
For example, it has 68
times the radius of our sun,
and it is 8.5
times the mass of our sun.
>> Kit (07:26):
Yeah, that's big. So remember that the
radius of our sun is about
432,000
miles, which is 109
times the radius of the Earth. So this is
a big star. It's likely
evolved right, um, on that main sequence, and
it's probably gonna be ready for a collapse sometime
(07:49):
soon.
>> Jordan (07:50):
Back in 2010, astronomers published a paper
suggesting the star might have a gas giant
about six times the mass of Jupiter
orbiting this star. But this hasn't yet been
confirmed, and there is some evidence to suggest
the initial findings might have been
incorrect or a star spot
or another artifact in the data.
>> Kit (08:11):
Yeah, I guess we're going to need some more research on this star
to learn more.
>> Jordan (08:15):
Perhaps it's there, perhaps it's not. One
other interesting thing I've learned about this star is that it is
the only star in Perseus that's
considered a navigational star.
>> Kit (08:26):
Oh, yeah. I don't think we've talked about navigational
stars on the pod before. Maybe we want to
do a quick snapshot on them and loop back on it some
other time, but just maybe a short picture of what a, uh,
navigational star is?
>> Jordan (08:39):
Kit, of course. And there are 58
special celestial navigation stars
in the night sky. Well, technically,
there's 57 and
Polaris, but these stars are used
to navigate by seafarers, especially since
on the sea, all you got is ocean.
(09:00):
Ocean. And if you look around, Kit,
you wouldn't believe me, but more ocean.
So if your satellites go down, or
perhaps you're trying to navigate by sea before we even
had satellites, perish the thought, and you want to
ensure you're going the right way, you could use these
very special stars to help guide your
(09:21):
ship.
>> Kit (09:22):
Yeah, very cool. Uh, and you know, there is celestial
navigation when you are, you know, wandering
around in other places, but it's pretty clear why you might
need stars since there is no landscape
to look at, uh, when you're on the ocean.
>> Jordan (09:35):
Let's move into our next segment, which is
Bayer's variable star. Here we
follow the Greek alphabet to learn more about the
Bayer designated stars in the night
sky. Last month, I swerved a little bit
and tried to find something a little bit more
interesting. No respect to Nu
Lyrae, but where did you go with this one,
(09:57):
Kit? Did you follow the alphabet and the
assignment, or were you
swept away by some other star of interest?
>> Kit (10:06):
Well, I'm famously only a
rule bender, not a rule breaker,
so I'm gonna do a little like. Yesa and
here.
>> Jordan (10:16):
Kit, you're almost the
avatar of rule bending.
>> Kit (10:20):
Thank you. Okay, so first things first.
Let's talk about Xi
persei, which is. It's spelled
sort of like, or it's transliterated as xi,
but it's pronounced, I think, K-See or
K-Sai something like this. It's Greek so I
don't know. It's a Greek letter. Um, this would come after
(10:40):
Nu in the Greek alphabet. Um, and this star also
has the name Menkib, which is
derived from an Arabic word meaning shoulder.
It has an apparent magnitude of positive
4.06, and it is an O type
blue giant star.
>> Jordan (10:56):
Since it is a blue giant, it's gotta be
pretty bright, right? So it's got to be far away
if the apparent magnitude is so high.
>> Kit (11:04):
Mm mhm hmm. Absolutely. So its
absolute luminosity is way,
way, way brighter than our sun.
And the star itself is 30 solar masses.
So it's huge and it's very bright and
luminous. But it's 1200 light years
away, so. So it's quite far
away. Exactly. Um, this star
(11:27):
is also a suspected runaway star,
and its radiation is part of the
reason why the Californa nebula, which is located
in Perseus seems to be glowing. If you've ever seen
a picture of that nebula.
>> Jordan (11:41):
All right, Xi Persei.
I don't know how to say you either, but pretty
cool.
>> Kit (11:47):
Yeah. So there was actually something kind of interesting about it.
So I wanted to, uh, wanted to make sure we got back on
track, but I also
really feel it's necessary that we do a quick shout
out to Beta Persei.
>> Jordan (12:00):
Kit. That is why you are avatar,
the last rule, bender.
>> Kit (12:06):
Well, I have to, because Beta
Persei is probably the most
famous star in this constellation.
It's also called Algol, which is
derived, again, from an Arabic phrase meaning the
head of the ghoul or the head of the
ogre. And this star is,
um, considered unlucky. It's known as the
(12:27):
demon star. It's known as Satan's
head. So, yeah.
>> Jordan (12:32):
Wow, that's quite an escalation. We started
from elbows and shoulders, but you keep making
your way up to the head and stuff starts getting
really real here.
>> Kit (12:41):
Yeah. So in the ancient Greek mythos,
this star is symbolizing that head of Medusa
that we mentioned earlier. And it, in
reality is actually, um, a three star
system. So it's been confirmed to have three,
um, stars. There might be some additional
companions, maybe even a five star system, or there
(13:01):
might be some, you know, optical binaries.
Um, and the main star
is, in fact, an actual variable
star.
>> Jordan (13:11):
Which means its brightness as perceived
from Earth, aka its apparent
magnitude, changes over time,
usually in a set interval or
within a relatively short period of
time. So this isn't something like a
supernova or a nova, where it brightens
temporarily and then fades.
>> Kit (13:32):
Exactly. So it sort of has this brightening and
dimming effect that happens over time. And this
variable brightness in Beta Persei
is caused by the orbits of the stars, which
cause them to eclipse one another at
these regular intervals. So
every three days or so, um, one
of the pairs, which is an eclipsing
(13:54):
binary pair, orbits each other, they eclipse
each other, and this pair is
0.062
au from each other.
>> Jordan (14:04):
Kit, that is very, very close.
>> Kit (14:07):
Uh-huh.
>> Jordan (14:08):
Let's remember that one AU
is about the distance from the Earth to the
sun. Though in 2012, the
IAU made a more specific redefinition.
>> Kit (14:19):
Yep, absolutely. So there's a slightly more technical
definition, but in general, we're talking about, you know,
much, much, much smaller,
these stars, right, orbiting one another very
closely. Um, and there are some really cool
visualizations of this system, so I
will be sure to post those over on our socials
(14:39):
at starrytimepod on the Universeodon Mastodon
server, and of course, over on Twitter.
>> Jordan (14:45):
Kit, I can't thank you enough for
getting Bayer's Variable Star back on track.
Let's take a quick break, and then we'll come back to find
out about my pick for gold star
of the month.
>> Kit (15:07):
Welcome back. This segment is called Gold
Star. In this segment, we alternate
picking the star or space object in our
constellation of the month that captures our
minds, our hearts,
and our very souls. So,
Jordan, what was your pick this month for gold star?
>> Jordan (15:28):
Well, Kit, there was a fair amount to choose
from this month in Perseus but
as soon as I read about this one particular
deep sky object, my decision was
made for me.
>> Kit (15:40):
Yeah, this part of the night sky is really
interesting because it does align with the galactic
plane of the Milky Way, but there's a
lot of sort of molecular clouds that are hiding and
obscuring the usual stuff that we see in this part of
the night sky and that we can sort of see on the galactic
plane.
>> Jordan (15:58):
Yes, Kit. Exactly. And one of
the major things in this constellation
is the Perseus cluster, which is
also known as Abell, or
Abell 426. And it's one
of the closest galaxy clusters to earth
at about
76.6
(16:19):
million light years away.
>> Kit (16:21):
You know, just a veritable hop and a skip away.
>> Jordan (16:24):
You know, Kit, it's all relative. It is one of the
closest. But what really captivated my
heart was the giant elliptical
galaxy at the center of this cluster
called NGC
1275, also known
as Perseus A, or
Caldwell 24.
>> Kit (16:45):
And these names are all so exciting and so
captivating.
>> Jordan (16:50):
Yeah, you instantly remember them. NGC.
What was the number again?
NGC 1275.
And Cornwell? No, Caldwell
24. This galaxy is a
Seyfert galaxy, which, at visible
spectrum, look like regular old
galaxies, but they have
(17:11):
extremely bright active
nuclei. And such active galaxies,
as they are called, are designed as
active galactic
nucleuses, or AGN's.
>> Kit (17:23):
Yep, and you're right. So we can
see these AGN's, these really active, bright
nuclei outside of the visible spectrum, so things
like radio and x ray, and this is important, The
Milky Way, our home galaxy, is
not an AGN
>> Jordan (17:40):
Kit, unfortunately, you are correct.
Our Milky Way, whatever it has going for
it does not have active
galactic nucleus status, because
these AGN galaxies have
supermassive black holes that are
actively accreting matter.
NGC
(18:00):
1275, as a Seyfert
galaxy, has a quasar like center.
NGC 1275 is
special since these Seyfert galaxies
only account for about
10% of all the galaxies that we
found
>> Kit (18:18):
So, rare and very active. Right. And
this idea that, you know, we in the Milky Way, we do
have a supermassive black hole at our center, but it's not accreting
matter. So. Okay, I'm still with you.
>> Jordan (18:29):
Kit, yes, this is a rare and
active galaxy. So pretty special to
me.
>> Kit (18:35):
Mhm.
>> Jordan (18:35):
And what stood out to me about it, in addition
to that, is that there's these super
elaborate filaments that surround the
galaxy. And these filaments, well,
essentially they're cool gas that's
been surrounded by super, very hot
interstellar gas. And now
here's where things get even more interesting.
(18:58):
This cooler gas is basically
deposited from the center of the galaxy
by radio bubbles.
>> Kit (19:06):
A radio bubble.
>> Jordan (19:09):
Radio bubbles.
>> Kit (19:11):
What?
>> Jordan (19:12):
Yes. So good.
Basically, bubbles of
relativistic plasma rise
out of that active nucleus and into the
surrounding hot, hot
gas and somehow have remained in
place instead of, you know, warming up
or collapsing into stars. Because of
(19:33):
this, some astronomers have hypothesized
that the magnetic field around these filaments
is keeping them intact.
>> Kit (19:41):
Oh, that is so interesting. Right. We have this, like, really
weird dynamic around it where it's like, yeah,
what? How are these cool parts of gas? Like, how
is this gas like this? Like, how is it here? That's
cool.
>> Jordan (19:53):
Two more things here, Kit. First, these
bubbles create sound waves, which
apparently sound like a b flat,
approximately 57 or
so octaves below middle C.
>> Kit (20:07):
Oh, my god. First of all, that is so low and
also so specific. Right? Like,
some astronomer was able to figure this
out. That's amazing. You can, like, hear
radio bubbles. That's. That's, like. Yeah, it's a little bit mind
boggling.
>> Jordan (20:22):
Kit, let me send you the link to put on our
socials, for sure. There's an excellent New York
Times article. Add it to your mixtape. And
finally, we've also observed
two supernovae in
NGC 1275. As
if we needed any other reason to give this
extremely cool space object the gold
(20:44):
star of the month award.
>> Kit (20:46):
What a great choice. This is a new galaxy
type for the pod, complete with a supermassive
black hole, my first love, mysterious
and beautiful filaments. Uh, a music
of its own. And supernovae.
Welcome to the Gold Star Club
NGC
1275.
>> Jordan (21:14):
That brings us to the end of our exploration
of the cosmic background of our
constellation Perseus. Next
week, we will be retelling and
reconstellationing the myths of this
constellation.
>> Kit (21:27):
This has been Kit
>> Jordan (21:29):
And Jordan.
>> Kit (21:30):
Sisters, lovers of stars and stories.
>> Jordan (21:33):
And we'll see you next time
>> Kit (21:35):
On Starry Time.
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