Sky & Telescope - March 2024 - 40

Variable Stars
9
10
hundreds of observers around the globe check T CrB on average
once every 12 minutes every hour of every day. Perhaps a
reader of this magazine will be the first to detect T CrB's rapid
brightness increase!
Another type of preparation involves proposals for " target11
12
2005
2010
2015
2020
Year
LEAD-UP
TO 2024 This closeup shows T CrB's brightness in visual
(V, in orange) and blue light (B, in blue) from 2005 to 2023. The rise from
the low state to the high state (starting around 2015) and the decline in
the pre-eruption dip (starting around March 2023) are both more prominent
in blue light. The 1927-to-1952 blue light curve is shown as the faint
blue line. Assuming the nova follows the same pattern it did in the 1930s
and 1940s, it should erupt soon.
either of these roadblocks, then the SD case takes a strong
hit. But if it avoids both roadblocks, then we have living proof
in favor of the SD solution for one of the premier controversies
in modern astrophysics.
Moving Forward
The upcoming T CrB eruption has excited much preparation
among both amateurs and professionals. For example, many
groups are monitoring T CrB to ensure that the start of its
rise is detected as early as possible. This is critical because
the star remains at peak brightness only for a short time.
The largest such program is ongoing with the AAVSO, where
2025
2030
of-opportunity " programs. In these cases, the telescope used
will go into a " stop-everything " mode when the start of the
eruption phase is detected. The first few days are likely to be
busy and confused, so a well-thought-out plan is necessary
for the best science return. For example, the team operating
the orbiting Neil Gehrels Swift Observatory have worked out
a detailed observing plan for the satellite's X-ray and ultraviolet
instruments. Similarly, neutrino detectors will lower their
event threshold for neutrinos coming from the direction of T
CrB, pushing to the lowest possible detection limits. With T
CrB being only 3,000 light-years away, it represents the best
chance for detecting nova neutrinos. In the first week of the
eruption, it's likely that the majority of professional telescopes
and space telescopes will be turned toward T CrB.
Observations will also continue long after the peak has
passed. For example, the Center for High Angular Resolution
Astronomy array for optical interferometry (on Mount
Wilson) and the Jansky Very Large Array radio telescope (in
central New Mexico) should both be able to see the expanding
nova shell. The Hubble Space Telescope will also watch
for the light echo, which will appear as an apparently expanding
ring or shell around the star and can be used to map the
distribution and quantity of mass in the prior ejecta.
As exciting as all this activity is, perhaps the most important
part of this T CrB eruption is that we can all look up, see
the Blaze Star, and ponder its titanic energies.
¢ BRAD SCHAEFER is a professor of astronomy and astrophysics
at Louisiana State University. He first estimated the
magnitude of T CrB back in high school.
WATCHFUL EARS The Jansky Very Large Array (JVLA) comprises 27 radio telescopes located in central New Mexico. The instrument
will be one of many that will closely follow the eruption of T CrB. In this case, the exquisite angular resolution of the JVLA will be able to
resolve the nova's expanding debris shell.
40 MARCH 2024 * SKY & TELESCOPE
B or V magnitude
GRAPH: BEATRIZ INGLESSIS / S&T, SOURCE: BRADLEY E. SCHAEFER / AAVSO;
VLA: NRAO / AUI / NSF

Sky & Telescope - March 2024

Table of Contents for the Digital Edition of Sky & Telescope - March 2024