# Tag Info

21

The connection between the dimming and a putative supernova relies on the interpretation that the decrease in luminosity may be due to circumstellar material, ejected in the years/decades/centuries immediately preceding a supernova. There are several mechanisms that could lead to this sort of mass loss (see slides 24-25), including gravity-wave driven ...

17

The American Association of Variable Star Observers tracks observations of a number of variable stars, including Betelgeuse. There are typically many such observations each day, primarily at visible wavelengths. It's quite easy to generate a light curve in the band(s) and date range of your choice. I'm also aware of a Twitter bot that tweets light curves ...

17

Distance measurements for Betelgeuse are a bit of a mess. Solutions based on parallax would be ideal, but Betelgeuse has a rather large angular diameter at most wavelengths thanks to its extended envelope; optical and infrared observations usually fall in the 40-60 mas range (see Dolan et al. 2016 for a recent review), while radio observations show a disk of ...

10

The problem is that the apparent diameter of Betelguese is about 50 mas (milli arc seconds --- 1 mas is about 5 nano-radians) while its parallax is about 5 mas and its shape and surface brightness are both irregular and variable. Given that, the current measurement are amazingly accurate. So I can identify about three approaches to doing this measurement, ...

9

The concept of a habitable zone really doesn't apply to a star like Betelgeuse. In addition to being a highly unstable and variable supergiant, it's a runaway star, suggesting that it was formerly a member of a multiple star system with a companion star that went supernova. Its relatively rapid rotation is difficult to explain via single star evolution, ...

9

Nobody knows the limits of the Sun's habitable zone, or how broad or narrow it is. Here is a link to a list of various estimates of the inner, or outer, or both, edges of the circumstellar habitable zone of the Sun: https://en.wikipedia.org/wiki/Circumstellar_habitable_zone#Solar_System_estimates Note that one well known estimate, that of Hart et al. in 1979,...

8

In principle yes, in practice no. The telescope is good enough, but the CCD camera will saturate, preventing a good positional measurement. Salient facts. The parallax to Betelgeuse as seen between Earth and New Horizons will be about 250 mas. The current distance uncertainty is ~20%, so to better that, the position of Betelegeuse measured by New Horizons ...

8

This is a partial and perhaps temporary answer only, posted in order to get to the bottom of this. I think that the comments are correct, you're probably seeing an artifact of image manipulation and the original data is just a 2D intensity map. I downloaded the original image at https://cdn.eso.org/images/screen/potw1726a.jpg, converted back to .png and ...

6

So the Hipparchos parallax of Betelgeuse doesn't seem accurate enough? If only someone would launch an even more advanced astrometric satellite than Hipparchos. Actually the ESA has launched an even more advanced astrometric satellite, Gaia, expected to operate from 2013 to about 2022. And it is possible that Gaia has already produced more accurate ...

6

There is an article here that describes the visible effects quite well. In essence, within a week or so, it would be comparable in brightness to the moon and therefore visible during the day. Betelgeuse would then start a phase of final, rapid dimming and again reach its current brightness level after possibly three years. After six years, it would be ...

5

Whatever is causing these tiny artifacts, it isn't astrophysical. The image obtained by ALMA is monochrome , i.e. obtained through a single frequency channel (4GHz width at 338 GHz - see O'Gorman et al. 2017, from where the original image came). The intensity map has then been colourised using a colour table, for public consumption. To establish any ...

5

Presumably, yes, EHT observations could improve on existing radio observations of Betelgeuse (e.g. recent ALMA images and comparatively ancient VLA images). Any observations would likely be targeted at known photospheric mm or super-mm emission from the star, mapping radius and temperature changes. The ALMA data showed the existence of a spot $\sim1000$ K ...

5

These measurements were made by Michelson & Pease (1921) using the 100-inch Cassegrain telescope at the Mount Wilson Observatory. Modern-day interferometry typically uses multiple telescopes (e.g. IOTA and the Keck Observatory interferometer), as this is typically needed to achieve long baselines (with long baselines admittedly being less important for ...

5

Barry Carter's nice piece of work contains 50 stars within $\sim 74$ light years of Betelegeuse. Leaving aside the question marks over exactly where Betelegeuse is (in terms of distance) and the parallax uncertainties of the 50 stars listed, there is also the problem that the faintest stars in the HYG catalogue are based on the Hipparcos catalogue, which is ...

5

Habitable zones, defined in terms of equilibrium temperature, scale with the square root of the luminosity of the star. So whatever the habitable zone limits $[a_{inner},a_{outer}]$ are for the Sun, for another star a good starting guess is $\sqrt{L/L_\odot}$ times those limits*. For Betelgeuse the simple-minded square root model gives a time-varying ...

3

The SIMBAD link might be there just because Osterbrock's 2004 AAS presentation about the interferometer mentioned an observation of Betelgeuse. This would be consistent with the policy stated in Wenger et al. 2000: No assessment is made of the relevance of the citation in terms of astronomical contents: the paper can be entirely devoted to the ...

3

Current measurements give a distance "somewhere between 567 light years and 835 light years", with a "best guess" of 724 light years. So wikipedia is being honest and saying "about 700". We really don't know any better. Earthsky.org is giving the "best guess" value. The app is probably using the distance measured by ...

3

Betelgeuse is large and close enough that it's angular diameter can be measured directly (via optical interferometry etc...) When you have the angular diameter, knowing the distance lets you calculate the radius with simple trigonometry. The fact that Betelgeuse has such a large angular diameter has actually made parallax measurements more difficult, ...

2

There have been 2 proposed spectroscopic companions, though never confirmed, traveling with Betelgeuse. These are thought to orbit the red supergiant. So when Betelgeuse eventually explodes, they would certainly be blasted by radiation, atmospheres could be damaged or completely destroyed, and would lose their host star sending them on a new trajectory ...

2

The answer lies in the sentence immediately before the one you quoted an excerpt of. In a study published in December 2000, the star's diameter was measured with the Infrared Spatial Interferometer (ISI) at mid-infrared wavelengths producing a limb-darkened estimate of 55.2±0.5 mas—a figure entirely consistent with Michelson's findings eighty years ...

2

Stars certainly do have radio emission from their photospheres, since blackbodies emit at all wavelengths. But that’s not usually what is detected, because it’s so faint. Doing some simple numbers, emission from a star like the Sun peaks at a wavelength of about 500 nm (= $5 \times 10^{-7}$ m), and the long-wavelength side of the Planck function, in the ...

1

Simbad is giving a catalogue of astronomical objects (that are identified in the Simbad catalogue) referred to in the AAS article. This is routinely done for most papers in the recognised astronomical literature. In this case, Betelgeuse appears to be the only star specifically mentioned in that AAS paper (actually just the abstract that is seen on the ADS ...

1

Look at this article: https://arxiv.org/abs/1706.06020. Depends on studies distance varies and this is probably the reason of this discrepancy. For instance Hipparcos catalogue gives $131^{+35}_{−23}$~pc, assuming pc=3.26ly it gives $\sim$427~ly. More details in attached article ;). We are waiting for results from Gaia mission, because at first it made ...

Only top voted, non community-wiki answers of a minimum length are eligible