When his daughter and son-in-law visited Ken Rohlf on his birthday in September 2023 to tell him they were expecting a child, two words came to mind for the soon-to-be-grandfather: "joyful" and "tough."

The first adjective is obvious, and proved to be true when Oliver was born this summer. The other, though, is because Rohlf knew someone would never meet Oliver, who's now 6 months old. Rohlf's wife, Sherri, died of pancreatic cancer on Christmas Day in 2018 and Rohlf knows she'd have loved being a grandmother.

"I felt there was a need to explain to our grandchild who his grandma was," said Rohlf, 61, who lives in St. Louis Park.

The result is "Christmas Sun: A Beautiful Tradition to Remember Grandma," a picture book Rohlf wrote and that he used artificial intelligence to illustrate. It explains to Oliver that his late grandmother was someone who loved sunsets and kids and whom they could remember every year by placing a memorial ornament, which depicts a glowing sun, on their Christmas tree.

With just 11 weeks between Sherri's diagnosis and death, there wasn't much time to make plans for the future, during which Ken took a leave of absence from his job as an attorney to care for his wife. The Rohlfs never had a chance, for instance, to talk about the possibility of being grandparents.

"At that point in time when my wife passed away, my daughter was not even married yet, so we had not discussed that," said Rohlf. The couple also have a son. "For me, two things came up after she passed: the thought of my daughter's wedding and then our first grandchildren. They were things you begin to think of, joyous celebrations that will also have other emotions that will be in play on those days."

Rohlf spent a lot of time thinking about that, so much so that when he sat down to actually write "Christmas Sun," he completed it in two days. The main thing he wanted to get across to Oliver, future grandchildren and anyone who reads "Christmas Sun" is that Sherri cared a lot about other people.

"This idea of grandma being this person who made you feel special, I wanted that to come out. That is who Sherri really was," said Rohlf. "She'd always ask about what was going on in your life, about your kids. Her amazing gift was that she had a really great memory. She remembered everything you would tell her and the next time she would see you, she would follow up on all of those things."

It made sense to express these ideas in a book — Rohlf's first, although he has since written two others that he hopes to publish — because Sherri was a book lover. In fact, for her memorial, the family received more than $37,000 in gifts that they turned over to the Eagan Rotary, of which Sherri had been a member. For the past five years, in her honor, the Rotary has given a book to every first-grader in Eagan's school district.

Rohlf self-published the book, which is available at his website and other online retailers and which he's hoping to get in some local stores.

A version of the ornament depicted in the book also is available. The author's dream is that people will keep the book and ornament in their boxes of holiday supplies, bringing them out every year as a sweet reminder.

"The holidays are this difficult time. Our society wants everything to be perfect around the holidays but it's also this time we take most, throughout the year, to think about people who are lost and gone. I think ['Christmas Sun'] could also be read by adults to remember people," said Rohlf, whose family has faced the melancholy brought each Dec. 25 by shifting their holiday celebration a few weeks earlier, to family gatherings at their cabin.

Rohlf has an inkling that his late wife would approve of the book, based on a trip to her mausoleum on a blustery day last spring.

"I went to visit, as you do, and kind of talk to her about this happening," recalled Rohlf. "All of a sudden, I felt this heat coming on my shoulders — it was the weirdest thing in the world — and I looked up. In one spot in the sky, the sun was shining and it was coming down right on me. So I think she probably would be very proud that we did this."