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OBSID:
24349
 Title:
The Secrets of Stellar Siestas: the Magnetic Grand Minimum Candidate HD 4915 
Investigator:
Saar
 Observer:
Saar, Steven
 Phone:
617 495 7046
 Email:
saar@cfa.harvard.edu
Target Name:
HD 4915
 Sequence Number:
201378
 Instrument:
HRC-S
 Grating:
NONE
 SI Mode:
HSO_0002B
 Raster Scan:
N
 Annotated DOT:
SEP0621a

Proposal Number:
22200238
 Right Ascension:
12.7952
 Declination:
-5.03928
 Status:
archived
 Start Date:
2021-09-10 10:26:55
Category:
STARS AND WD
 Type:
GO
 AO Cycle:
22
 Dither Flag:
Y
 Y Offset:

 Z Offset:
Est. Count Rate:
7.5e-15
 Order-1 Count Rate:

 Exposure Time:
20.00
 Time Remaining:

 Reqd Start Time:

 Reqd Stop Time:
Period:

 Epoch:

 Start of Period:

 End of Period:

 PS Margin:

 PE Margin:

 Max Segments:
0

Trigger Level:
DEF
 Range Switch Lvl:
DEF
 Spect Mode:
DEF
 Antico Enab:
DEF
 Width Enab:
DEF
 Width Thold:
DEF
 Uld Enab:
DEF
 Upper Lvl Disc:
DEF
Blank Enab:
DEF
 U Blank Hi:
DEF
 V Blank Hi:
DEF
 U Blank Lo:
DEF
 V Blank Lo:
DEF
 Py Shutter Pos:
DEF
 My Shutter Pos:
DEF
 Timing Mode:
N

Abstract:
Magnetic grand minima (MGM) are mysterious episodes when the Sun's magnetic dynamo cycle "takes a siesta" and goes into temporary quiescence. The phenomenon has never been observed in modern times; what was the Sun like then? Recently a star was observed to have a decaying cycle amplitude (in Ca HK), making it a strong candidate for an MGM episode. We propose to study the star with Chandra and HST, to explore magnetic heating throughout its outer atmosphere. Results will be compared with cycle minima and stars with "flat activity" (objects which may be in MGM or have "dead" dynamos) to explore similarities and differences, and reveal what may lie in store for our own Sun in the near future.

Remarks:
It would be idea, but not necessary, to have the Chandra and HST observations scheduled within a few months of each other.

psci Run:
60
 Processing Date:
Sep 26 2021
 psci Directory:
/nfs/maaxnew/r3/fc/acis117b/acis117.log
OBSID:
24349
 SIM Mode:
HRC-S
 OTG Mode:
NONE
 Seq Number:
SEP0621a
 Target Name:
Histogram_I
 AO:
0
Start VCDU:
65671:040
 Start Time (UTC):
253:38994.817
 Stop Time (UTC):
253:58619.322
 Kilosecs:
19.6
 % Frames:
0.3
 # CCDs:
I5
# Frames:
6055
 # Events:
0
 Events/sec:
0
 PSCI errors:
0
 % drops:
0.0
 Bias Errs:
0
 FP Temp:
-119.2
Parameter Block:
0x0023a024
 Window Block:
0x00038014
 # Windows:
10
 FEP Mode:
Te3x3
 BEP Mode:
EH
 Start Row:
0
 # Rows:
1024
Primary Exposure:
32
 Secondary Exposure:
0
 Duty Cycle:
0
 Summing?:
No
 Bias?:
Yes
 Trickle?:
No
 Bias Run:
60

pgf@space.mit.edu Thu Apr 3 20:00:53 EST 2025