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chornedsnorkack
2018-Jul-17, 04:30 PM
How much mass is found in solar neighbourhood?
Within 5 pc of Sun, I seem to find the following:
Magnitude 1 - 1 dwarf, Sirius A, 1,42, A1, 2,06
Magnitude 2 - 1 dwarf, Procyon A, 2,66, F5, 1,50
Magnitude 3 - 0
Magnitude 4 - 2 dwarfs, Rigil Kentaurus A, 4,38, and Sun, 4,85, both G2, 1,10 and 1, combined 2,1
Magnitude 5 - 2 dwarfs, Tau Ceti, 5,68, G8, 0,78, and Rigil Kentaurus B, 5,71, K1, 0,91, combined 1,69
Magnitude 6 - 2 dwarfs, Epsilon Eridani, 6,19, K2, 0,82, and Indi, 6,89, K5, 0,76, combined 1,58
Magnitude 7 - 1 dwarf, 61 Cygni A, 7,49, K5, 0,70
Magnitude 8 - 3 dwarfs, 8,16...8,69, K7...M0, 0,67...0,60, combined 1,9
Magnitude 9 - 1 dwarf, Lacaille 9352, 9,75, M0, 0,50
Magnitude 10 - 8 dwarfs, 10,20...10,89, M1...M3, 0,45...0,40, combined 3,4
Magnitude 11 - 7 red dwarfs, 11,09...11,97, M3, 0,35...0,26, combined 2,1, and 1 white dwarf, Sirius B, 11,34, DA2, 1,02
Magnitude 12 - 1 white dwarf, Procyon B, 12,98, DQZ, 0,60
Magnitude 13 - 6 red dwarfs, 13,07...13,51, M3...M4, 0,17, combined 1,0, and 1 white dwarf, Gliese 440, 13,18, DQ6, 0,75
Magnitude 14 - 5 red dwarfs, 14,03...14,97, M4...M5, 0,13...0,14, combined 0,7, and 1 white dwarf, van Maanen´s star, 14,21, DZ7, 0,68
Magnitude 15 - 10 red dwarfs, 15,17...15,85, M5...M6, 0,11...0,10, combined 1,05
Magnitude 16 - 5 red dwarfs, 16,05...16,98, M5...M6, 0,10...0,09, combined 0,5
Magnitude 17 - 2 red dwarfs, 17,22...17,32, M6, 0,08, combined 0,16
Magnitude 18 - 1 red dwarf, GJ1245C, 18,46, M5, 0,07
Magnitude 19 - 2 red dwarfs, 19,37...19,41, M8, 0,07, combined 0,14

antoniseb
2018-Jul-17, 05:15 PM
I don't see a total. If you do total it up you should include the Sun.

chornedsnorkack
2018-Jul-17, 06:22 PM
What I get:
4 white dwarfs, magnitude 11,34...14,21, mass 0,60...1,02, combined 3,05
46 red dwarfs, magnitude 9,75...19,41, mass 0,07...0,50, combined 9,4
10 yellow dwarfs, magnitude 4,38...8,69, mass 0,60...1,10, combined 8,0
2 massive main sequence dwarfs, magnitude 1,42...2,66, mass 1,50...2,06, combined 3,56
Total mass of 58 main sequence stars: 21 solar
4 remnants - 3,05 solar, as stated before.
total 62 stars - 24 solar masses.
How much interstellar gas is within 5 parsecs of Sun?
How much dark matter is?

kzb
2018-Jul-18, 12:30 PM
0.0594 solar masses of stars per cubic parsec:

https://arxiv.org/abs/1807.04592

Cougar
2018-Jul-18, 04:25 PM
How much interstellar gas is within 5 parsecs of Sun?
How much dark matter is?

As to dark matter - and check my math on this - the volume of dark matter in which our galaxy is embedded (about 1016 ly3 using a sphere with radius 200,000 ly) is about 1012 times larger than the volume within 5 parsecs (~18,000 ly3). The mass of the galaxy's dark matter is about 1012 solar masses. So I get (very roughly) about 1 solar mass of dark matter within 5 parsecs.

I know - this assumes the dark matter density is uniform throughout its volume, which it is not, but this is a very rough, back-of-the-envelope estimate, and I wouldn't be too surprised if there are other errors in the logic.

I see now that the radius of the dark matter halo is more like 300,000 to 400,000 ly. That increases the total DM volume by at least an order of magnitude. My low estimate there works against my simplified DM uniform density assumption, so (until corrected) I'll stick by my very rough estimate that it's somewhere around 1 solar mass of dark matter within 5 parsecs.

DaCaptain
2018-Jul-18, 04:56 PM
How much interstellar gas is within 5 parsecs of Sun?
How much dark matter is?

Kind of a side question but if I were traveling at 1/2 the speed of light through this space would I be slowed down by it the DM and Interstellar gas?

kzb
2018-Jul-18, 05:04 PM
If you have not seen it you may want to look at the RECONS site, although annoyingly the summaries have not been updated since 2012:

http://www.recons.org/

I believe they expect GAIA will add up to 10% more stars to the within-10pc census.

chornedsnorkack
2018-Jul-18, 06:39 PM
Note that over half of the total mass, about 12,5 solar, is in 50 stars magnitude 9,75 or dimmer - 46 red and 4 white dwarfs. The 12 stars magnitude 8,69 or brighter are less than half the total mass, about 11,5 solar.
The dimmer stars:
Lacaille 9352 - 9,75, 1,1 % solar
Gliese 832 - 10,2, 0,7%
Groombridge 34 A - 10,32, 0,6%
Gliese 412 - 10,34, 0,6%
Gliese 1 - 10,35, 0,6%
Lalande 21185 - 10,44, 0,6%
Kapteyn - 10,87, 0,4%
AD Leonis - 10,87, 0,4%
Gliese 687 - 10,89, 0,4%
So far, 5,4 % solar brightness combined
3 stars at 0,3 % each
5 stars at 0,2 % each
8 stars at 12,98...13,51 summing up to maybe 0,3 %
So, all stars magnitude 9,75 are maybe 7,6 % solar brightness combined.

Hornblower
2018-Jul-18, 11:23 PM
What I get:
4 white dwarfs, magnitude 11,34...14,21, mass 0,60...1,02, combined 3,05
46 red dwarfs, magnitude 9,75...19,41, mass 0,07...0,50, combined 9,4
10 yellow dwarfs, magnitude 4,38...8,69, mass 0,60...1,10, combined 8,0
2 massive main sequence dwarfs, magnitude 1,42...2,66, mass 1,50...2,06, combined 3,56
Total mass of 58 main sequence stars: 21 solar
4 remnants - 3,05 solar, as stated before.
total 62 stars - 24 solar masses.
How much interstellar gas is within 5 parsecs of Sun?
How much dark matter is?

I estimate about 4 solar masses of interstellar gas, from the density of about 0.3 particles per cubic centimeter, with most of it being hydrogen. See this Wiki article:
https://en.wikipedia.org/wiki/Local_Interstellar_Cloud
I remember in my youth hearing that there is about as much matter between the stars as in them. That now appears to be overestimated for our immediate region. If we include dark matter, it may be pretty close.

dtilque
2018-Jul-19, 02:16 AM
There's 11 known brown dwarfs in that sphere. They won't add much, perhaps as much as a couple M-type red dwarfs. But there certainly more to be found.

chornedsnorkack
2018-Jul-19, 04:28 AM
The brighter stars:
Magnitude 8:
AX Microscopii, 8,69, 2,9 %
61 Cygni B, 8,31, 4,1 %
Groombridge 1618, 8,11, 4,6 %
Magnitude 7:
61 Cygni A, 7,49, 8,8 %
Magnitude 6:
Epsilon Indi, 6,89, 15,2 %
Epsilon Eridani, 6,19, 30 %
Magnitude 5:
Rigil Kentaurus B, 5,71, 45 %
Tau Ceti, 5,68, 45 %
Magnitude 4:
Sun, 4,85, 100 %
Rigil Kentaurus A, 4,38, 152 %
combined: 407 %
magnitude 2:
Procyon A - 2,66, 750 %
magnitude 1:
Sirius A - 1,42, 2500 %
Total is 36 solar luminosities.
Sirius A is twice as bright as the remaining 61 stars taken together.
The 12 brighter stars have less mass than the 50 dimmer stars combined, but about 500 times the luminosity.

kzb
2018-Jul-20, 03:19 PM
Our nearest interstellar neighbour, if you can call it that, is a gas cloud 10,000AU across:

A dense plasma globule in the solar neighborhood

https://arxiv.org/abs/1710.07652

Not sure what the mass is.

antoniseb
2018-Jul-20, 03:53 PM
Our nearest interstellar neighbour, if you can call it that, is a gas cloud 10,000AU across: ...
Wow! I don't know how that bit of news escaped my notice! BTW, at 1 to 3 parsecs, is *might* be our closest neighbor.

chornedsnorkack
2018-Jul-21, 08:29 AM
More observations:
Sirius A is thought to have been about 5 solar masses on main sequence. It therefore shed about 4 solar masses of gas about 120 million years ago.
Procyon B was about 2,6 solar masses on main sequence and therefore shed about 2 solar masses about 1200 million years ago.
Sirius and Procyon B shed about 6 solar masses of gas between them.
The two lone white dwarfs are less constrained, but it is a reasonable approximation that the four white dwarfs between them have shed 12 solar masses in last few Gyr.
The total mass of main sequence is just 17 solar masses.

kzb
2018-Jul-23, 11:54 AM
Wow! I don't know how that bit of news escaped my notice! BTW, at 1 to 3 parsecs, is *might* be our closest neighbor.

Buried in the text (page 8) of this earlier article, they claim to have a robust distance estimate of this cloud, 1.5pc with a maximum error of 0.5pc.

But the size estimate is much smaller than the more recent article, 100AU versus 10,000AU. Which is a bit puzzling. )These papers are highly technical and I don't pretend to fully understand them

The intra-hour variable quasar J1819+3845: 13-year evolution, jet
polarization structure and interstellar scattering screen properties

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.758.1021&rep=rep1&type=pdf

kzb
2018-Jul-23, 12:01 PM
More observations:
Sirius A is thought to have been about 5 solar masses on main sequence. It therefore shed about 4 solar masses of gas about 120 million years ago.
Procyon B was about 2,6 solar masses on main sequence and therefore shed about 2 solar masses about 1200 million years ago.
Sirius and Procyon B shed about 6 solar masses of gas between them.
The two lone white dwarfs are less constrained, but it is a reasonable approximation that the four white dwarfs between them have shed 12 solar masses in last few Gyr.
The total mass of main sequence is just 17 solar masses.

The mass of gas in the galaxy disk is a lot smaller than that of stars, according to all current models. You can find articles which give the masses of each component (stars, gas and dark matter) in the galaxy.

The white dwarfs and Procyon might not have been anywhere near us when they shed all that material, it was several galactic rotations ago.

selden
2018-Jul-23, 01:10 PM
Buried in the text (page 8) of this earlier article, they claim to have a robust distance estimate of this cloud, 1.5pc with a maximum error of 0.5pc.

But the size estimate is much smaller than the more recent article, 100AU versus 10,000AU. Which is a bit puzzling. )These papers are highly technical and I don't pretend to fully understand them

The intra-hour variable quasar J1819+3845: 13-year evolution, jet
polarization structure and interstellar scattering screen properties

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.758.1021&rep=rep1&type=pdf

My interpretation of the papers is that the larger size was measured directly from observation of radio radiation emitted by the globule while the smaller size mentioned in the PSU paper was measured indirectly from the lack of detectable effects on background objects. The "globule" paper mentions

We argue in §3 that the scintillations were caused at the turbulent boundary of the globule.

chornedsnorkack
2018-Jul-23, 04:32 PM
The mass of gas in the galaxy disk is a lot smaller than that of stars, according to all current models. You can find articles which give the masses of each component (stars, gas and dark matter) in the galaxy.
Do they also provide the breakdowns of star mass by groups (bright massive stars; individually dim red dwarfs; individually dim white dwarf, neutron star and black hole remnants; gas passed by these remnants, and when)?


The white dwarfs and Procyon might not have been anywhere near us when they shed all that material, it was several galactic rotations ago.

Seeing how the white dwarf count is just 4, it may not be statistically representative, yes.
Of the 4, the dimmest is van Maanen´s star, at 14,21. Its radius is 0,011 solar, temperature 6220 K and age estimated at 3100 million year as white dwarf. Mass 0,7 solar masses as white dwarf, estimated 2,6 on main sequence, so total age about 4100 million years - younger than Sun.
Milky Way is supposed to have formed a few hundred million years after world, and white dwarfs can form in 100 million years (see Sirius B). There should be 13 Gyr old white dwarfs around. How cool are they now? And how dim?

kzb
2018-Jul-24, 04:42 PM
Back in 2012, the 10pc sample consisted of 259 stellar systems. There were 20 white dwarfs

http://www.recons.org/census.posted.htm

By 2018 there are 317 systems listed within 10pc, and two more white dwarfs discovered, presumably making a total of 22:

http://www.recons.org/published44.pdf

73% of the 10pc stars are class M.

It is estimated to be at least 90% complete.