LAX to IND redeye (Boeing 727) photo bombs M33 A Survey of - PowerPoint PPT Presentation

LAX to IND redeye (Boeing 727) photo bombs M33

A Survey of Luminous Stars in M31 and M33 John C. Martin & Logan Kimball University of Illinois Springfield

Check Out Bill Rea’s Paper Cookbook for Mira Spectroscopy with a filter wheel (SA100 or SA200) grating 2019, JAAVSO Vol 47, No 1

Intro & Thanks • I am: – John C. Martin – Observatory Director & Associate Professor • University of Illinois Springfield • Thanks to: – National Science Foundation – UIS Barber Endowment – Collaborators • Roberta Humphreys • Kris Davidson • Michael Gordon • UIS Observatory Volunteers

Henry R. Barber Research Observatory Volunteers: Jim O’ Brien, Jennifer Hubbell-Thomas, Kevin Cranford, Greg Finn, John Lord, Mary Sheila Tracy, Logan Kimball, Eric Schlaf, Keith Gibbs, Steve Verhulst, Bruce Patterson

Problem: Stars Live too Long Star lifetimes >> Human lifetimes We get a snapshot in time and have to connect the dots to interpret what we see. We must worry about bias due to our point of view!

Star Evolution 150 1 star Stellar Mass (in M ☉ 10 10 stars 2 50 stars 0.5 500 stars 0.08 0.01 0.1 1 100 10 Relative Number of Stars

High Mass vs Low Mass Difference in Life: Stars < 2 M ¤ Stars > 2 M ¤ • P-P Chain Fusion • CNO Cycle Fusion • Radiative Core • Convective Core • Convective Envelope • Radiative Envelope

Predictions for a 25 M ☉ star Duration Core Hydrogen fusion 7 million years Core Helium fusion 700 thousand years Carbon Fusion 600 years Core Neon Fusion 1 year Core Oxygen Fusion 6 months Core Silicon Fusion <1 day

Issues Close To Home Dust!

M31 M33 Andromeda Triangulum Galaxy Galaxy 131 targets 73 targets 6+ years = longest dedicated survey of these two galaxies

SN Impostors Quiescent LBVs Humphreys – Davidson Limit Yellow Void (Warm Hypergiants) 10 +6 WR Luminosity (x Solar) 50M ☉ Hyashi Limit B[e]sg Yellow Super Red Super Giants Giants 10 +5 25M ☉ 10M ☉ 10 +4 20,000 40,000 10,000 5,000 2,500 Temperature (Kelvin)

Classified Targets Classification done by collaborators at UMN using spectra from Large Binocular Telescope (LBT) M31 M33 Type Number Type Number Of/late-WN 5 Of/late-WN 10 OB Supergiants 12 OB Supergiants 36 8 B[e]sg 11 B[e]sg Warm Hypergiants 4 Warm Hypergiants 6 Yellow Supergiants 12 Yellow Supergiants 23 LBV 5 LBV 4 19 Candidate LBV 5 Candidate LBV Peculiar/Unknown 11 Peculiar/unknown 13

Photometric Survey Overview • Images – 20’x20’, limiting mag ~ 19.5 – Four filters, BVRI • Always image V and at least one other – Cadence of at least once per year • Photometry – DAOphot PSF fitting • Aided by Massey LGGS catalog – APASS photometric system – Color transformed

Images • 647 images total – M31 = 463 – M33 = 183 Start V and R Start B • Four Filters Start I – V @ every epoch – R from 2012 – present – B from 2013 – present – I from 2015 – present Astrodon high-throughput Johnson-Cousins Filters B has NO red leak

Check Stars

Photometric Uncertainty

Target Curation V-073136 (J013342.52+303258.6) 10” • OB-Supergiant in M33 • V ~ 17.48 (B-V) ~ 0.28 Target Notes: Many LGGS stars >3 mag fainter within 5 arcsec. Normally resolved from LGGS star J013342.26+303301.6 approaching comparable brightness 4.4 arcsec NW. 5” 5” 5” I V B

Variability From Correlation • If star is variable, bands change in phase • 4 bands = 6 pairs • Calculate R 2 correlation coefficient M31-004507.65 (YSG) R 2 V B R B 0.92 (11) R 0.98 (8) 0.81 (6) I 0.97 (7) 0.97 (3) -.– (1)

Variability From Correlation • Certain = – At least two band pairs (N > 5) and (R 2 > 0.60) • Likely = – At least one band pair (N > 5) and (R 2 > 0.60) M31-004033.80 (OBsg) R 2 V B R B 0.23 (11) R 0.03 (8) 0.39 (4) I 0.00 (6) -.-- (2) -.– (2)

̅ Welch & Stetson (1993) • Calculate statistics between 2 bands – I = measure correlation • Expectation value = 0 for non-variable • Negative if inverse correlation – R = measure ratio between band fluctuations • Depends on type of variable ∑ 𝑤 ! 𝜀𝑤 ! = 𝑤 ! − ̅ 𝑤 𝑥 = ' 1 $ 𝜏 ",! $ $ 𝜏 !,# 𝑤 = 𝜏 ",! 𝑥 $ 1 ∑ 𝜀𝑐 ! ∑ 𝜀𝑤 ! 𝐽 = 𝑜 𝑜 − 1 & 𝜀𝑐 ! 𝜀𝑤 ! 𝑆 = + !"#

Welch & Stetson (1993) For B & V

Welch & Stetson (1993)

Variability 2012-16 Class N Certain Likely Total Of/late-WN 16 0 (0%) 0 (0%) 0% OB Supergiants 48 5 (10%) 1 (2%) 12% Yellow Supergiants 35 6 (17%) 4 (11%) 28% Warm Hypergiants 10 0 (0%) 2 (20%) 20% B[e] Supergiants * 11 1 (9%) 1 (9%) 18% Classical LBV 9 7 (78%) 1 (11%) 89% Candidate LBV 23 2 (9%) 1 (4%) 13% (Martin & Humphreys, 2017, AJ, 154, 81) * Sample adjusted for bias

Variability (current) Class N Certain Likely Total Of/late-WN 16 1 (6%) 0 (0%) 6% OB Supergiants 48 5 (10%) 2 (5%) 15% Yellow Supergiants 35 6 (17%) 9 (26%) 43% Warm Hypergiants 10 2 (20%) 1 (10%) 30% B[e] Supergiants * 11 2 (18%) 2 (18%) 36% Classical LBV 9 8 (89%) 0 (0%) 89% Candidate LBV 23 4 (17%) 2 (9%) 26% * Sample adjusted for unbiased comparison • w/ 2 more years 30% more variables identified

Limitations • Precision ~ 0.1 mag – Brighter stars = lower error per obs • Comparison ensemble – Room for improvement • Field Crowding – Greater issue in M33 than M31 • Time scales sampled – ranging weeks to years

Variability (m v < 18.5) Class N Certain Likely Total Of/late-WN 12 1 (8%) 0 (0%) 8% OB Supergiants 44 5 (11%) 2 (4%) 16% Yellow Supergiants 33 6 (18%) 9 (28%) 46% Warm Hypergiants 8 2 (25%) 1 (13%) 38% B[e] Supergiants 8 2 (25%) 1 (13%) 38% Classical LBV 9 8 (89%) 0 (0%) 89% Candidate LBV 19 4 (21%) 1 (5%) 26%

Candidate LBVs Class N N w/ Variable? m v < 18.5 m v < 18.5 Fe Emission Stars 10 7 1 (14%) Of/late-WN 8 7 0 (0%) OB Supergiants 3 3 3 (100%) Yellow Supergiants 2 2 1 (50%) • Incidence of variability in OB Supergiants = 16% • Incidence in OB Supergiant LBV-Candidates = 100%

Exceptional Example M31-004341.8 (Of/late-WN) One LGGS star 2 magnitudes fainter 4 arcseconds to S does not interfere significantly with PSF fit. Seven other LGGS stars >3.5 magnitudes fainter within 5 arcseconds. R 2 V B R B 0.83 (16) R 0.70 (11) 0.71 (8) I 0.39 (13) 0.56 (3) -.– (1)

Exceptional Example Period = 160 days Amplitude = 0.0625 mag Model includes 3 harmonics

Red Supergiants • Candidates identified in M31 – Down to M v ~ -4.5 (15 M ☉ ) • Captured serendipitously in our survey • None have “disappeared” • Potential for similar analysis with them

Results • Longest dedicated survey of M31 & M33 – Published 4-year photometry catalog • Through year 6 on the web. • Baselines in BVRI for (182) luminous stars – Additional value to be mined from images • 30% more variables detected – Ability to distinguish improving w/ more data – Difference in variability between classes http://go.uis.edu/m31m33photcat

Additional Opportunities • Faint limit ~ 19.5 – Abs Mag ~ -4.5 in M31 & M33 – Main sequence ~ 30 M ☉ – RSG ~ 15 M ☉ • Phot error < 0.1 mag • Possibilities: – Novae – Un-Nova (disappearing RSG) – The BIG one. http://go.uis.edu/m31m33photcat