More space news!

[tkdguy]

Sorry about the long loading time.

[DShomshak]

Hey, it's not your fault I'm too poor to afford broadband. Or that COVID-19 has closed the local library so I can't use its WiFi. I appreciate everyone who posts these links, even if I can't always use them.

 

Dean Shomshak

[Cancer]

Another take on the black hole merger exposing things in the "mass gap", from the American Astronomical Society.  No video here.  Not technical journal grade reading, either.

 

https://aasnova.org/2020/09/02/ligo-virgos-newest-merger/

[Cancer]

Quote

π Earth: A 3.14 day Earth-sized Planet from K2's Kitchen Served Warm by the SPECULOOS Team

 

Prajwal Niraula et al. 2020 AJ 160 172

 

Abstract

We report on the discovery of a transiting Earth-sized (0.95 R ⊕) planet around an M3.5 dwarf star at 57 pc, EPIC 249631677. The planet has a period of ∼3.14 days, i.e., ∼ π, with an installation of 7.45 S ⊕. The detection was made using publicly available data from K2's Campaign 15. We observed three additional transits with SPECULOOS Southern and Northern Observatories, and a stellar spectrum from Keck/HIRES, which allowed us to validate the planetary nature of the signal. The confirmed planet is well suited for comparative terrestrial exoplanetology. While exoplanets transiting ultracool dwarfs present the best opportunity for atmospheric studies of terrestrial exoplanets with the James Webb Space Telescope, those orbiting mid-M dwarfs within 100 pc such as EPIC 249631677b will become increasingly accessible with the next generation of observatories.

 

I am almost certain that "installation" there should be "insolation", so the second sentence is saying that the exoplanet receives 7.45 as much stellar energy per square meter as Earth does.

 

Otherwise, it seems these guys have got a little punny.  I haven't read the paper to see if it continues there.

[tkdguy]

I'm surprised this hasn't been posted yet: Gas giant orbits white dwarf

 

This means the planet is larger than the star it orbits.

[Cancer]

You can get the Nature paper for that via this link.  I haven't had time to read it yet.

[archer]

3 hours ago, tkdguy said:

I'm surprised this hasn't been posted yet: Gas giant orbits white dwarf

 

This means the planet is larger than the star it orbits.

 

"When you have a problem THIS big, try Gas-X."

[Cancer]

The Nobel Prize in Physics for this year was given earlier this week to Roger Penrose, Reinhard Genzel, and Andrea Ghez for work on black holes in general and the one at the center of our Galaxy in particular.

 

There's nice little video from the UCLA group (Ghez's group) of the motions of the stars over about 20 years from Keck telescope imaging data.  The black hole itself is of course not visible in the images, but its location is indicated in the video.  There is no sound with the video.  The star whose orbit is marked in yellow went through another periapse (closest approach to the black hole) in May 2018, a couple years after this video was posted.

 

It is possible to do spectroscopy for at least some of these stars and use the Doppler effect to measure the orbital velocities; this has been done for same star as mentioned above, though I haven't seen the velocities near the last periapse published.  The fit to those data that I have seen has the star moving at upwards of 4000 km/sec at closest approach, "only" 1.3% of the speed of light.

[L. Marcus]

A respectable speed, by most standards.

[novi]

https://phys.org/news/2020-10-supergiant-star-betelgeuse-smaller-closer.html

 

And now for an orange gas-bag that's not threatening us with an apocalypse, scientists have narrowed down the exact size and distance to Betelgeuse.  Namely, only 500 or so light-years away, which is still plenty far to be safe from its supernova.  And only about a billion kilometers in diameter, not a billion miles.  Also, since it's one of the few stars big enough to see as an actual disk, as opposed to a point, they can make measurements (astroseismology and star spots) to figure out what's going on inside the star.  And those measurements push back the date of the supernova - they suggest that the core is still in a helium-burning stage.  That's at least thousands of years from a supernova, and could be closer to a million.  OTOH, other measurements suggest it has been a red supergiant for a while, which is why they keep saying a supernova in about 100,000 years, as it splits the difference.

 

So no boom today, or tomorrow.

[DShomshak]

The latest episode of NOVA is "Touching the Asteroid," about the OSIRIS-REx mission to collect a sample of the asteroid Bennu. Which it apparently has done. Woohoo! (Though we still have to wait three years for the sample to be returned to Earth. Bummer!)

 

Dean Shomshak

[pinecone]

I just heard about a possable sign of a superstring being detected, if I get a chance I will add a link.

[archer]

14 hours ago, pinecone said:

I just heard about a possable sign of a superstring being detected, if I get a chance I will add a link.

 

Did it make a low thrumming sound when you plucked it?

[L. Marcus]

It was either a string or a jockstrap-type.

[pinecone]

Finally found it. 

 

[tkdguy]

The link isn't showing up.

[pinecone]

I don't know why it would not appear. It works when I click on it....dunno.

[DShomshak]

Could someone please summarize for those of us who can't watch videos due to slow connections?

 

Dean Shomshak

[archer]

Astronomers find fast radio burst source

 

https://apnews.com/article/astronomers-find-cosmic-radio-source-9aa883306b24272e6fa44c501b5ade11

[Cancer]

(same subject, this link is to Nature)

 

Includes links to the technical papers.

[Cancer]

On 10/19/2020 at 11:53 PM, novi said:

https://phys.org/news/2020-10-supergiant-star-betelgeuse-smaller-closer.html

 

And now for an orange gas-bag that's not threatening us with an apocalypse, scientists have narrowed down the exact size and distance to Betelgeuse.  Namely, only 500 or so light-years away, which is still plenty far to be safe from its supernova.  And only about a billion kilometers in diameter, not a billion miles.  Also, since it's one of the few stars big enough to see as an actual disk, as opposed to a point, they can make measurements (astroseismology and star spots) to figure out what's going on inside the star.  And those measurements push back the date of the supernova - they suggest that the core is still in a helium-burning stage.  That's at least thousands of years from a supernova, and could be closer to a million.  OTOH, other measurements suggest it has been a red supergiant for a while, which is why they keep saying a supernova in about 100,000 years, as it splits the difference.

 

So no boom today, or tomorrow.

 

Finally had half an hour to track this down and read it (it is behind the paywall).  The new data they present are photometric measurements from a satellite (Solar Magnetic Ejection Imager, SMEI) whose principal mission was to observe the Sun, but the brightest stars around the ecliptic are also in the data set and they have extracted brightness measurements for Betelgeuse from that, over the timespan early 2003 to mid 2011.  (Taking consistent-quality long-term photometric measurements of a really bright star is not an easy thing to do, so this is a valuable dataset.) 

 

Present-day mass is 15.6 to 19 solar masses, and "early core helium-burning stage", which puts core collapse a ways off in the future.  Initial mass was in the range 18 to 21 solar masses.  It's a semiregular pulsating variable star, with a fundamental period about 416 days and a first overtone period of 185,5 days.  They were most interested in modeling the pulsations, as pulsation gives you some interesting information about the internal structure of the star.

[tkdguy]

NASA resumes contact with Voyager 2

[Cancer]

In a paper accepted to the Astronomical Journal, a big batch of authors have reexamined the Kepler mission data with the results of the GAIA stellar parallax mission to do a better estimate of the number of rocky, Earthlike planets in their Habitable Zones in the Galaxy.  This frequency of occurrence of habitable-zone rocky planets around Sun-like stars, is also known as “η⊕”.  A 32-page motherbear of a paper even leaving out the figures, appendices, tables, references, etc., their main text closes with

 

Quote

... we find that, for the conservative habitable zone, η⊕ is between 0.37 +0.48/−0.21 and 0.60 +0.90/−0.36 planets per star, while for the optimistic HZ η⊕ is between 0.58 +0.73/−0.33 and 0.88 +1.28/−0.51 planets per star. These occurrence rates imply that conservatively, to 95% confidence, the nearest rocky HZ planet around G and K-dwarfs is expected to be be within ∼ 6 pc [...]. Furthermore, there could, on average, be 4 HZ rocky planets around G & K dwarfs, respectively, within 10 pc from the Sun.

 

The link is to the arXiv preprint server, so it is free access, but it is technical journal paper and no apologies.

 

Note also that because the Kepler mission omitted M dwarfs from their target list, the habitable zone planet (of admittedly unknown composition because it doesn't transit in front of its star) orbiting Proxima Centauri is NOT among the numbers quoted in their final paragraph.

[Cancer]

On 8/18/2020 at 12:57 AM, tkdguy said:

 

 

Arecibo has had another cable snap in the last couple of days.

[tkdguy]

That really bites.