WD1856 exhibits transits that are 57 % deep every 1.41 days. The original goal for the photometry observations reported here was to provide an accurate transit light curve that could be used to improve the TESS transit depth (5 %) and shape, in order to establish a case for obtaining expensive observing time on professional telescopes (the 10.4-meter Gran Telescopio Canarias, the world's largest optical telescope, and the Spitzer Space Telescope). Those measurements allowed modelers to establish that the occulting body is a planet the size of Jupiter, with a mass less than 7 times Jupiter's. Currently, the goal for the observations on this web page is to search for transit timing variations (TTV), and possible depth changes, both of which could be produced by a massive planet in an outer orbit of the same system. 

Why WD 1856+054 is Important For decades astronomers have wondered if planets could survive the transition that most stars undergo after their normal lifetime of converting hydrogen to helium in their cores. When the hydrogen is exhausted the star swells to thousands of times its original size, becoming a red giant, and in the process consuming inner solar system planets. Eventually the red giant shrinks to an even smaller size than when it was a normal star, becoming a white dwarf that is only slightly larger than the Earth. Our sun (and solar system) is 4.5 billion years old; it has another 4 or 5 billion years before it undergoes the red giant/white dwarf transition. Afterward, our sun will remain a white dwarf forever – for 100 billion years, or however long the universe lasts. Stars like our sun will therefore spend most of their total lifetime as a white dwarf. Astronomers have had a long-standing question: “Will any of our solar system planets survive and orbit our diminutive sun during its white dwarf eternity?” With the discovery of a planet orbiting white dwarf WD 1856+534 we can now say that this is possible; survival of some of our outer planets may continue to orbit our white dwarf sun forever. The planet orbiting WD1856 is the size of Jupiter, which is 7 times larger than the white dwarf. Its mass could be comparable to Jupiter's, and it orbits the star every 1.4 days. If our sun has a similar fate it might be said that for the majority of our solar system’s lifetime (of 100 billion or more years) it will be a white dwarf orbited by only Jupiter, for example.

Figure 1.2.

Figure 2. Merging of data for the best 11 observing sessions of this year. 


Figure 3.  The first 6 dates subset of above data.

Model is a fit to this data subset.


Figure 4. The last 5 dates subset of data in Fig. 2. Model is a fit to this data subset.

This last two figure can be used to answer the question "Has the dip changed depth, width or shape since 2019 Oct 22?" We have three epochs to compare: 2019 Oct 22 (GCT), 2020.06.11 to 2020.08.09 (HAO), and 2020.0819 to 2020.10.10 (HAO). Width hasn't changed (7.36 min, 7.56 min, 7.44 min), nor has depth (56.8 %, 57.3 % and 57.3 %). SEs will eventually be needed.
 

Individual Observing Sessions

  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 This site opened: 2019.10.18.