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Improved Estimates of the Distance To the Large Magellanic Cloud
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.
Now my navigation system will be able to estimate the arrival time correctly. Why did this take so long?
I take it that you didn't notice the papers being published for free on the arXiv, then? Seriously, here is a direct link to download the main paper described in the summary.
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.
Learning HOW to think is more important than learning WHAT to think.
in Kessel Runs ?
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 invalidated all the best dark matter idas. For the first time in at least a couple of decades, there's hard data that there's not a good theory for. And it's only precise measurements that can move physics forward, by culling all the bad ideas that look really good on paper.
Socialism: a lie told by totalitarians and believed by fools.
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