Exoplanets!

 I did a lot of citizen science observations during my sabbatical last fall. I was especially interested in trying to use my time to make observations of exoplanets.

My exoplanet observations were all made using the transit method. These planets are impossible to see directly but they can still be detected. As an orbiting exoplanet passes directly in front of (transits) across the face of its star it makes a mini-eclipse and blocks a small percentage of the star’s light. This can be measured even with small telescopes, making this technique the most successful method for studying exoplanets. A typical exoplanet observation lasts from four to five hours, though some are shorter, and others are longer.

Over the course of the semester, I attempted to observe sixteen exoplanet transits. Due a variety of factors (weather, equipment failure, etc.), not all of them were successful. All of my observations were made with a Unistellar eVscope2. A summary of my exoplanet observations is included below along with other findings about these exoplanets.

A note about exoplanet names. Most of them are terrible acronyms of the survey the first discovered the exoplanet, followed by a letter, which indicates the order of discovery within that particular system (starting with the letter b). As an example WASP stands for Wide Angle Search for Planets. WASP-33b refers to the first planet (b) within the 33^rd system discovered by that survey. Some exoplanet names are acronyms within acronyms. TOI is TESS Object of Interest. TESS is the Transiting Exoplanet Survey Satellite.

XO-7b               Observed August 23/24, 2024 & October 5-6, 2024

A graph of the science results is generated for each exoplanet observation. The graph for one of my two observations of XO-7b is above. Note that the dates are given in Universal Time (essentially, the time in Greenwich, England) which is why these graphs don’t always agree with the local date.

XO-7b is a gas giant planet that orbits a spectral type F star that is larger and hotter than the Sun. It is located 764 light-years from Earth in the constellation of Draco, the Dragon. It is an example of a “hot Jupiter” type planet, as are the majority of exoplanets that can be observed with a small telescope. It is located very close to its parent star, at a distance that is just 4.421% of the distance Earth is from the Sun. It orbits its parent star every 2.9 Earth days! The planet is smaller than in mass (0.709 times Jupiter’s mass or 225 times Earth’s mass), but larger than Jupiter in size. Its larger size is because the tremendous heat that it receives from its star essentially inflates the planet giving it a radius that is almost 1.4 times that of Jupiter’s. The calculated temperature for the planet is 2,678^oF. 

TOI-1518b                     Observed August 27/28, 2024

Note: there were clouds at the end of the observation.

TOI-1518b is a gas giant planet that orbits a rapidly rotating F-type star, which is larger than the Sun (1.95 times the Sun’s radius) and 2,750^oF hotter than the Sun’s surface temperature. It is located 737 light-years from Earth in the constellation of Cepheus, the King. The planet has a mass 2.3 times that of Jupiter and a radius that is 1.9 times that of Jupiter. More massive gas planets tend to be smaller as the extra mass causes more compression from gravity. The fact that TOI-1518b is so large indicates that it is inflated due to the temperature caused by how close it is to its star. It orbits its star every 1.9 days in an orbit that is just 3.89% the size of the Earth-Sun distance. The planet is considered to be an ‘ultra-hot’ Jupiter. Its dayside temperature has been measured to be 5,367 ^oF! It is believed to have ionized iron vapor in its atmosphere.

TOI-1259 Ab                 Observed September 24/25, 2024

The TOI-1259 is a binary star system. The system is located 385 light years from Earth in the direction of the constellation of Draco, the Dragon. TOI-1259 A is a spectral type K star that has a radius 71% of the Sun’s and is about 2,000^oF cooler than the Sun. The other star, TOI-1259 B, is a white dwarf. The white dwarf is a distant companion, being 1648 times farther from A than the distance between Earth and the Sun. White dwarfs are essentially dead stars. In this case TOI-1259 B would have begun as a star that was more massive than A (1.59 times the mass of the Sun) and burned through its hydrogen fuel at a faster rate. It now has a mass of 0.56 times the mass of the Sun. Astronomers have determined the age of the white dwarf, and thus the age of the system, which is thought to be 4.8 billion years (Our solar system is 4.6 billion years old.).

The exoplanet is named TOI-1259 Ab. It is a gas giant planet with a mass is 0.44 of Jupiter’s but it is slightly larger than Jupiter in size (1.02x Jupiter’s radius). It orbits star A every 3.5 days at a distance of 4.07% of the Earth-Sun distance.

Observations at Palomar and Keck suggest that the planet receives extreme heating on its dayside which is both causing some of its atmosphere to escape to space and also driving extreme winds that blow from the dayside to the night side of the planet. The equilibrium temperature of the planet is estimated to be 1,190 ^oF. 

WASP-33b                    Observed September 25/26, 2024

WASP-33b is a gas giant exoplanet 398 light years in the direction of the constellation of Andromeda. It orbits a variable star which is larger (1.5 times the Sun’s radius) and nearly 3,000^oF hotter than the Sun. It orbits the star every 1.2 Earth days (!) at a distance that is just 2.39% of the distance between the Earth and Sun. Unlike most planets, WASP-33b has a retrograde orbit, meaning that it does not revolve in the same direction that its star rotates. It has a mass that twice that of Jupiter and is about 1.9 Jupiters in radius. The temperature of the exoplanet is 5,790^oF. Researchers using the Hubble Space Telescope have detected titanium oxide, a major component of sunscreen, in the atmosphere of this planet. Iron and silicon have also been detected in its atmosphere.

WASP-2b                      Observed September 27, 2024

WASP-2b is a hot Jupiter-type gas giant planet that orbits a K-type star located 500 light years from Earth in the direction of the constellation of Delphinus, the Dolphin. The planet’s host star has a mass that is 85% of the Sun’s, it is 82% of the Sun’s radius. It is 1,154^oF cooler than the Sun. The planet has an orbital period of 2.2 Earth days at a distance that is just 3.1% of the distance between the Earth and Sun. Its mass is 93.1% of Jupiter’s and it is slightly larger than Jupiter in size. The planet has a density similar to that of water. The temperature of the exoplanet is 1,855^oF. Spectroscopic observations suggest that it has a cloudy atmosphere. 

WASP-93b                    Observed September 28/29, 2024

WASP-93b is a hot Jupiter-type gas giant planet that orbits an F-type star located 1,208 light years from Earth in the direction of the constellation of Cassiopeia, the Queen. This star is both larger and hotter than the Sun.

The planet has an orbital period of 2.7 Earth days and orbits at a distance that is just 4.2% of the Earth-Sun distance. It has 1.47 times Jupiter’s mass and is 1.7 times Jupiter’s radius.  The planet’s equilibrium temperature is estimated to be 3,000^oF.

HAT-P-32b                    Observed October 4/5, 2024

HAT-P-32b is a gas giant planet that orbits a type F star located 943 lights from Earth in the direction of the constellation of Andromeda, the Princess. The planet has a mass that is just 68% that of Jupiter. It orbits its star at a distance that is just 3.3% of Earth’s distance from the Sun. Its close distance to its star has inflated the size of the planet making it nearly twice Jupiter’s radius. This in turn means that the planet has a low density. All of the “hot Jupiters” observed so far have densities lower than water’s 1 g/cm³, meaning that they are made of light materials (in our Solar System only Saturn, which has a density of 0.69 g/cm³ has density lower than water). HAT-P-32b has a density of just 0.1085 g/cm³  this is low enough to almost put it into the category of “super-puff” (yes, that’s a real thing) exoplanets, which have densities less than 0.1 g/cm³.

TIC 362220946.01     Observed October 10/11, 2024

TIC 362220946.01 is a possible exoplanet that was first observed by NASA’s TESS satellite. It was thought that this planet has an orbital period of 8 days and a mass that is 23 times that of Jupiter. I was one of nine observers from the U.S. and Mexico who looked this system in an attempt to confirm its existence and the possible orbital period of the planet. The results were inconclusive but there are suggestions that this could perhaps be a binary star system instead of a planetary system. Further observations may help to solve this puzzle.

WASP-77 Ab                Observed October 24/25, 2024

WASP-77 Ab is another “hot Jupiter” type gas giant planet. It is located 343 light years from Earth and orbits a Sun-like star in the constellation of Cetus, the Whale. The star is part of a wide binary system, where the other star is a spectral type K star that is smaller and cooler than the Sun.  has a mass 1.67 times that of Jupiter and is 1.23 times Jupiter’s radius. It orbits its star every 1.4 Earth days at a distance of 2.3% that of the Earth-Sun distance. The planet has a calculated temperature of just over 2,600^oF.

TOI 6881.01                 Observed October 31, 2024

The exoplanet known as TOI 6881.01 orbits a star that is 2,559 light years from Earth in the direction of the constellation of Perseus, the Hero. Its star is larger, hotter and more massive than the Sun. The planet orbits its star every 1.9769 days. The planet has a calculated equilibrium temperature of almost 3,100^oF. The planet has a mass that is essentially the same a Jupiter’s and a radius 1.44 times that of Jupiter, making it another “hot Jupiter” gas planet that has expanded from the extreme heat from being right next to its star.

TOI-5571.01                 Observed December 4, 2024 & December 18, 2024

TOI-5571.01 was initially detected by NASA’s TESS satellite, but its observations were widely spaced in time and so the orbital elements of this exoplanet were highly uncertain. Early observations suggested that the exoplanet could have an orbital period of 731 days (2 years) but was more likely to be something shorter. My observation was part of a campaign by Unistellar to help pin down the exact orbital period of the planet. My observations the night of December 4 (my birthday!) did seem to catch the exoplanet transiting in front of its star (though it was low in the sky), which may indicate that the planet’s orbital period is potentially 66 days, but further observations are needed. 

The Sun and the Moon in Motion and Jupiter too!

 This fall I have been on a sabbatical from my teaching and focusing on lots and lots of backyard astronomy. 

One of my early observing goals was to capture the Sun every day for an extended period to show its rotation. I was able to image it every day for 17 consecutive days - from August 20th through September 5th. I then aligned the images to produce this animation showing the Sun's rotation:

Another interesting way to look at this is to add the images together, which produces this:

This nicely shows that sunspots occur in parallel stripes on either side of the Sun's equator.

I have also been able to shoot the Moon on consecutive nights to show its changing phases and the effect of lunar libration (a kind of tilting and rocking). Here's how the Moon looked from October 7th through the 15th, as it went from a waxing crescent to nearly full:

You should be able to see that the Moon looks to be somewhat growing in size - not just the amount illuminated by the Sun, but larger. This is because the Moon's orbit is not a perfect circle and over the nights I shot these the Moon was moving towards Earth.

And then after a few nights of clouds I was able to capture the Moon again from October 18th through the 27th, showing it moving through its waning phases:

Again, I think you can also see here that the Moon appears to be getting smaller. That was because it was moving away from Earth in its orbit.

I don't usually have the opportunity to stay up late (or get up early) enough to shoot the waning phases, so this was a treat.

I had another stretch of clear nights again in November and I was able to capture the Moon from November 6th through the 14th as it moved from a waxing crescent to full.

Finally, here's Jupiter and its moon Europa as they looked the night of December 14th.

This is about an hour and 20 minutes of motion showing Jupiter's Great Red Spot rotating out of view to the right, along with other cloud features in Jupiter's atmosphere. Europa is the spot of light to the left of Jupiter.

April 8th's 'Smart' Total Solar Eclipse

This post comes about three months later than it should but, as they say, better late than never. I had an amazing trip to Hamilton, Texas to witness the total solar eclipse. I did my best to both capture the eclipse and to travel light. The photo is me with my Unistellar Odyssey Pro telescope and a DSLR camera at left.

 

 

The Odyssey Pro is Unistellar's newest 'smart' telescope. It's a small lightweight telescope, with a primary mirror just  3 1/3", but it takes super images. Last fall Unistellar improved their software to make solar observing much better but this was going to be the first time anyone had tried using a 'smart' telescope for observing a total solar eclipse. So how did it do? 

All-in-all, it did pretty well. 

Thankfully, during the first half of the eclipse the weather was mostly cloudless. The telescope had no trouble finding, focusing (it has auto focus) and tracking on the Sun. But as the eclipse progressed and the Sun began to take on more of a crescent appearance the tracking wasn't very good and I had to manually correct the tracking to keep the Sun in view. 

My biggest concern was totality. How would the telescope and its software handle seeing the Sun when the Sun didn't look like it normally does? Would the exposures be okay? Color was a big concern too. As I have mentioned before the color that the Unistellar telescopes and app give when imaging the Sun is artificial. The telescope's sensor sees farther into the infrared than our eyes do and that adds extra red to the image making the uncorrected image look sort of lavender in color. The app changes the color pallet to give the Sun a more pleasing yellow color. How would it look during totality?

Yellow. Very yellow.

Thankfully, this yellow color cast was easy to correct in Photoshop and I was able to get images like the two below. 

Visually, the eclipse was amazing. Ethereal, even. The large red prominence seen at the bottom of the image above was very easy to see with unaided eyes and the corona was fantastic. 

There was no way for the Odyssey telescope to capture much of the Sun's corona as its field-of-view is far too small. That's why I brought my DSLR. 

I have now seen two total solar eclipses and I don't really feel that any image can adequately capture the beauty of the corona, but I am happy with this image.

After totality, I was so euphoric that it was difficult to remember to keep taking images of the Sun to complete the time-lapse sequence I was shooting, but then the clouds rolled in and it no longer mattered. Still, I was happy to get the entire first half of the eclipse plus totality and that's all that mattered. 

I would rate the experience as a total success. Using a 'smart' telescope allowed me to travel with far less gear than most people who photographed the eclipse and I am happy with my results. The next total tolar eclipse isn't until 2026 and I am sure that by then the technology will be even better.

Disco Sunspots!

 Back in October I posted about using a disco ball to observe a solar eclipse. It turns out that you can also use a disco ball to safely observe sunspots too. Here's how I did so earlier today.

Really all you need is a disco ball, a place to secure it in the sunlight and a shadowed area to project the image of the Sun. Here I have my disco ball sitting on a tripod for a Unistellar telescope. I aligned the disco ball so that it reflected an image of the Sun into my house and nearly 70 feet down a dark hallway on to a sheet of white paper. Here's the result:

It's not a great image, but you should notice a definite gray smudge-like area on the projected image of the Sun. That's a big sunspot that is visible on the Sun today. I also imaged the Sun with a Unistellar Odyssey Pro telescope and solar filter. I got this image which I rotated to match the orientation of the projected image above.

As you can see, that's the same sunspot group in both images. This is another confirmation that a disco ball is an excellent tool for safely observing the Sun.

Jupiter's Moons: Himalia, Elara and Pasiphae Too

It's no secret that I like to use my Unistellar telescopes to track down obscure things and to create animations of them moving in the sky. Back in August I managed to track down Saturn's faint moon Phoebe (on my blog here). 

Now that Jupiter is in opposition its time once again for me to take a look at it and some of its family of moons. The four Galilean moons are bright and easy to see with any optical magnification - even binoculars will work if you can hold them steady enough. 

Here's a shot of them taken in late October when Jupiter was also near enough to a background star that was almost as bright as one of the moons.

Jupiter has 96 (!) known natural satellites, but most people only ever see the four pictured above. Back in 2021 (when there were only 80 known moons of Jupiter) I first blogged about trying to extend my view to include Jupiter's moon Himalia. I found it, but wasn't very happy with my results, so I revisited finding that moon again last year (on my blog here) and now that I have just seen it again, I suppose that it has become an annual thing for me.

The animated gif below is from two images taken 58 minutes apart on 9 November 2023. Himalia can be seen moving pretty close to dead center and the glow of Jupiter is on the left. I circled it to make it easier to see.

That worked out pretty well. Well enough that I wondered if there were any other Jovian moons that I might be able to catch. 

Moons like Amalthea are bright enough, but far too close to the glare of Jupiter for me to ever be able to see. Some of them are just too small and faint, but Elara is just bright enough and far enough from Jupiter for me to be able to photograph it with my 4.5" telescope.

Elara and Himalia are in the same group (the Himalia group) of Jovian irregular satellites. With a diameter of 105.6 miles Himalia is larger than tiny Elara, which is just 53 miles across. As you can see from the graphic above (which I created using the SkySafari app), Elara is a bit farther away from Jupiter. It takes 260 days (8 1/2 months!) for it to complete an orbit around Jupiter. Himalia orbits just a bit faster, swinging around Jupiter ever 251 days (That's still a long time.).

I was a little worried because I had some cirrus clouds in the way and SkySafari (by far my favorite astronomy app) doesn't always have the best coordinates for these faint irregular moons. I pointed my telescope at the position listed and saw this:

There's a moving object in the lower right corner which at first I thought was Jupiter's satellite Elara. It was only later (after I put up an earlier version of this post) that I realized that I hadn't checked to see if there were any known asteroids in the area. Sure enough, that's the asteroid known as (933) Moultona.

Well, rats. What I needed was more accurate coordinates. Thankfully, JPL's Horizons System is an easy resource for getting accurate coordinates for small solar system objects.

I pointed my 4.5" telescope at the right place and gave it another shot. Was I able to spot a moon that's just 53 miles across from a distance of over 376 million miles?  Yes, though the glare from Jupiter was far worse than it was for Himalia (and strangely red too).

It's pretty tough to spot in the full frame, so I have posted a cropped animated gif version with Elara in a circle.

According to JPL's Horizons System Elara has an apparent magnitude of 16.625, just over half a magnitude fainter than what SkySafari listed. There's one other irregular satellite of Jupiter that is near to that magnitude: Pasiphae, with a magnitude of 16.877, it's only a bit fainter than Elara. With a diameter of 36 miles it is smaller but, thankfully, it is also farther away from the glare of Jupiter. In fact it is a lot farther from Jupiter. 

Here it is: 

Pasiphae has a retrograde orbit (meaning it orbits backward relative to the orbits of all of Jupiter's regular moons) that takes 764 days to complete. Yes, it takes just over two Earth years to circle Jupiter! Since Pasiphae and even Elara and Himalia take so very long to circle Jupiter, what we are seeing here isn't much of any of their orbital motions. Instead, most of their motion in the sky is because Earth itself is a moving object. During the hour or sow between images Earth moved much more in its orbit around the Sun than Jupiter and its family of moons did, allowing them to be seen against the much further background stars.

Solar Eclipse!

On October 14, 2023 along a line from Oregon through Texas there was an annular eclipse. The rest of the continental U.S. got to see a nice partial solar eclipse. 

I observed the partial eclipse along with about 50 others at Palomar College where I teach astronomy.

The eclipse crowd at Palomar College (that's my shadow in front)

As you can see from the photo above we had perfect weather and the eclipse did not disappoint. 

Here's a photo taken when the Moon had maximum coverage over the Sun from our vantage point:

Image captured using a Unistellar eQuinox 2 telescope

Thanks to the dedication of Palomar student Tomas Chester we were able to capture a time-lapse video of the entire event. Here's what it looked like: 

About two weeks before the eclipse I learned of a very cool outreach tool that helps to make eclipse viewing safe and fun - a disco ball. (See the paper: Why every observatory needs a disco ball). I immediately purchased a disco ball and set it up on the day of the event.

Above left is a standard disco ball. Each of the mirrors acts like a pinhole camera and reflects an image of the sun. The image on the right shows many images of the partially eclipsed Sun projected by the disco ball during the eclipse. It was very popular with our crowd and gave an almost magical view of the event. I highly recommend using a disco ball for every eclipse outreach event.

This eclipse was sort of a preview for an even better one - a total solar eclipse that will take place on April 8, 2024. Weather permitting it will be visible along a path from Mexico, up through central Texas and up toward the northeast U.S. and into Canada. I plan on observing that one and I will bring my disco ball with me.

Here Comes the Sun

The most viewed post on my blog from last year was Observing the Sun with an eVscope. Everything about that post is now completely out of date thanks to some recent and exciting updates from Unistellar with the new release of version 2.5 of their app.

What's in version 2.5? The ability to have one of their telescopes to automatically find and guide on the Sun. Of course, to observe the Sun you need a safe solar filter that goes on the front end the telescope. 

Above is my eVscope 2 outfitted with the new solar filter available from Unistellar. 

The new version of the app includes the Sun in the catalog (see below), though it strangely describes it as a planet. When you choose the Sun it will remind you that you need to have a solar filter in place before pointing the telescope at the Sun. Pointing at the Sun without having a filter on it will ruin your telescope.

Pointing at the Sun is automatic, unlike previously where the telescope had to be manually pointed by looking at the shadow of the telescope. Once the telescope is pointed at the Sun it now automatically tracks on the Sun, which is also a major improvement, as the old version had no tracking. That made focusing very difficult as the Sun was always drifting across the field of view. Now, focusing is much easier, especially with the Sun having so many sunspots.

So how does it look?

Image of the Sun taken September 23, 2023

Great! Unistellar seems to be applying a color shift to the image to give it a pleasing look. Images taken prior to the app update made the Sun look very un-Sun like (see image below taken last year). I used to always convert them to grayscale because I couldn't stand the color. 

Also, I suspect that the Unistellar app is now applying a sharpening routine to the images of the Sun when you save them, but that's okay, as they look great. 

All of this is perfect timing as there is a solar eclipse happening in 3 weeks, another one in April and solar maximum is just around the corner! Expect to see more solar image posted here soon.