Improved Estimates of the Distance To the Large Magellanic Cloud 56
Long-time Slashdot reader colinwb writes: A team of researchers has published a letter in Nature (2019) estimating the distance to the Large Magellanic Cloud" to a precision of one per cent; Arxiv (2019).
The Arxiv abstract: In the era of precision cosmology, it is essential to empirically determine the Hubble constant with an accuracy of one per cent or better. At present, the uncertainty on this constant is dominated by the uncertainty in the calibration of the Cepheid period — luminosity relationship (also known as Leavitt Law). The Large Magellanic Cloud has traditionally served as the best galaxy with which to calibrate Cepheid period-luminosity relations, and as a result has become the best anchor point for the cosmic distance scale. Eclipsing binary systems composed of late-type stars offer the most precise and accurate way to measure the distance to the Large Magellanic Cloud. Currently the limit of the precision attainable with this technique is about two per cent, and is set by the precision of the existing calibrations of the surface brightness — colour relation. Here we report the calibration of the surface brightness-colour relation with a precision of 0.8 per cent. We use this calibration to determine the geometrical distance to the Large Magellanic Cloud that is precise to 1 per cent based on 20 eclipsing binary systems. The final distane is 49.59 +/- 0.09 (statistical) +/- 0.54 (systematic) kiloparsecs.
In 2013 a team of researchers (including several of the current researchers) published a letter in Nature (2013) which estimated the distance with a precision of two per cent; Arxiv (2013).
Another team of researchers has also posted their recent research on Arxiv (2019) in which they provide a 1% foundation for the determination of the Hubble Constant.
All the links are to abstracts; the full letters to Nature are paywalled, but the Arxiv abstracts have links to PDFs which seem to be complete and accessible.
The Arxiv abstract: In the era of precision cosmology, it is essential to empirically determine the Hubble constant with an accuracy of one per cent or better. At present, the uncertainty on this constant is dominated by the uncertainty in the calibration of the Cepheid period — luminosity relationship (also known as Leavitt Law). The Large Magellanic Cloud has traditionally served as the best galaxy with which to calibrate Cepheid period-luminosity relations, and as a result has become the best anchor point for the cosmic distance scale. Eclipsing binary systems composed of late-type stars offer the most precise and accurate way to measure the distance to the Large Magellanic Cloud. Currently the limit of the precision attainable with this technique is about two per cent, and is set by the precision of the existing calibrations of the surface brightness — colour relation. Here we report the calibration of the surface brightness-colour relation with a precision of 0.8 per cent. We use this calibration to determine the geometrical distance to the Large Magellanic Cloud that is precise to 1 per cent based on 20 eclipsing binary systems. The final distane is 49.59 +/- 0.09 (statistical) +/- 0.54 (systematic) kiloparsecs.
In 2013 a team of researchers (including several of the current researchers) published a letter in Nature (2013) which estimated the distance with a precision of two per cent; Arxiv (2013).
Another team of researchers has also posted their recent research on Arxiv (2019) in which they provide a 1% foundation for the determination of the Hubble Constant.
All the links are to abstracts; the full letters to Nature are paywalled, but the Arxiv abstracts have links to PDFs which seem to be complete and accessible.
Re:Paywall (Score:5, Informative)
I take it that you didn't notice the papers being published for free on the arXiv, then? Seriously, here [arxiv.org] is a direct link to download the main paper described in the summary.
Re: (Score:2)
Thanks, but the numbers are no good. It's moved since then!
Finally (Score:5, Funny)
Now my navigation system will be able to estimate the arrival time correctly. Why did this take so long?
Re: (Score:2)
I’ve never believed your stated Kessel Run times anyway, Han.
Re: (Score:3)
I've never believed your stated Kessel Run times anyway, Han.
Of course you mean, "Kessel Run distances". (In this case, "run" means "route".)
From: 'Solo: A Star Wars Story' Solves The Kessel Run Problem [forbes.com]
According to Star Wars: The Essential Atlas and the Solo novels, the road to Kessel involved navigating a cluster of black holes known as 'the Maw'. This would typically take 18 parsecs -- to avoid falling into the Maw's gravity wells -- but with a sturdy ship like the Millennium Falcon and a daring captain like Han, a smuggler could skirt close to the edges of the Maw and cut the distance down to 12 parsecs.
Re: (Score:1)
Units of Distance (Score:5, Informative)
1 Parsec = 3.26 light years
1 Kiloparsec = 3262 light years
1 light year = 9.46 trillion kilometers = 5.88 trillion miles
Further than the Basingstoke Roundabout, so stick out your thumb and be prepared for a long trip.
Re: (Score:1)
Re: (Score:3)
Re: (Score:2)
Re: (Score:2)
Just get familiar with zettametre (Zm), the Magellanic clouds are 1.5 to 1.8 Zm away.
So how huch is that (Score:3)
in Kessel Runs ?
Re: (Score:2)
Real ones, or Han's boring shortcut
1% Accuracy good??? (Score:2)
Space is Big, Really Big, you won't believe how mindbogglingly huge it is. You might think it is a long way to the Chemist, but that is just peanuts to space, LISTEN! (Apologies to Douglas Adams)
But the size of space, 1% is just a really big number. Lets just say there is a 1% chance you will get hit by a car every day. That means on the average you will be hit by a car 3-4 times every year, for most people that is a lot of times getting hit by a car.
Re: (Score:2)
Cosmology and astronomy are not engineering disciplines. Different people have different strengths and abilities. It's like demanding entomologists abandon the study of insects so they can cure cancer.
Re: (Score:2)
That sounds suspiciously like the plot for the 1992 movie Medicine Man [imdb.com].
Re: (Score:2)
Basic research may have far-reaching ramifications in the future. In the 18th century, electricity was little more than a parlor trick, and researchers into electricity and its effects weren't exactly doing anything all that memorable through the lens of useful research. By the mid-19th century, the world's first telecommunications system was being built.
Trying to force every scientist to solve today's problems does nothing but starve the future. And really, engineering is applied science. It is not science
Re: (Score:2)
Ever heard of dark energy? Yeah, it's the most promising area right no for "new physics", and so fairly important. And that's all about measuring the distance to very distant objects.
Re: (Score:2)
Re: (Score:3)
Once the actual nature of dark energy and dark matter are determined they may have broad implications for every day life but they also may not.
This is open-ended research, not engineering. You don't expect to know what the practical results will be. That's sort of the point. No one did basic physics in order to develop radiation treatments for cancer, or MRI or PET scans or CAT scans, but we got them all the same. Mostly from the tools built to do the research.
What we do know is all of this mass and energy interacts very weakly with the rest of the mass and energy we can see.
There's something else vital that we know: existing theory doesn't explain either. Physics has been high-centered for some time now for lack of new data that doesn't fit theory. The LHC
A delight of the southern sky (Score:4, Interesting)
I always take a telescope with me whenever I visit the southern hemisphere and have spent many evenings (mainly from Australia) exploring the Large Magellanic Cloud. The Tarantula Nebula is one of those must-see items on any such trip.
The Small Magellanic Cloud doesn't have as many goodies but has 47 Tucanae next door which more than makes up for it.
...laura
How accurate can the measurements be? (Score:2)
How does one measure the distance to a cloud? Are they measuring to one specific star in the cloud? If not... How to measure the distance to something that has no defineable edges or centre?