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

Relative Number of Stars 0.01 0.1 1 10 100 Stellar Mass (in M☉ 2 0.5 10 150

1 star 10 stars 50 stars 500 stars

0.08

High Mass vs Low Mass

Stars < 2 M¤

• P-P Chain Fusion
• Radiative Core
• Convective Envelope

Stars > 2 M¤

• CNO Cycle Fusion
• Convective Core
• Radiative Envelope

Difference in Life:

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 Andromeda Galaxy M33 Triangulum Galaxy

73 targets 131 targets 6+ years = longest dedicated survey of these two galaxies

B[e]sg Luminosity (x Solar) Temperature (Kelvin)

10,000 5,000 2,500 20,000 40,000 10+4 10+5 10+6

Hyashi Limit

10M☉ 50M☉

Red Super Giants

25M☉ SN Impostors

WR Yellow Super Giants

Yellow Void (Warm Hypergiants)

Humphreys – Davidson Limit

Quiescent LBVs

Classified Targets

M31

Type Number Of/late-WN 5 OB Supergiants 12 B[e]sg 11 Warm Hypergiants 4 Yellow Supergiants 12 LBV 5 Candidate LBV 5 Peculiar/Unknown 11

M33

Type

Number

Of/late-WN

10

OB Supergiants

36

B[e]sg

8

Warm Hypergiants

6

Yellow Supergiants

23

LBV

4

Candidate LBV

19

Peculiar/unknown

13

Classification done by collaborators at UMN using spectra from Large Binocular Telescope (LBT)

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

• Four Filters

– V @ every epoch – R from 2012 – present – B from 2013 – present – I from 2015 – present

Start B Start I Start V and R

Astrodon high-throughput Johnson-Cousins Filters B has NO red leak

Check Stars

Photometric Uncertainty

Target Curation

V-073136 (J013342.52+303258.6)

• 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.

V B I

5” 5” 5” 10”

Variability From Correlation

• If star is variable, bands change in phase
• 4 bands = 6 pairs
• Calculate R2 correlation coefficient

R2 V B R B 0.92 (11) R 0.98 (8) 0.81 (6) I 0.97 (7) 0.97 (3)

• .– (1)

M31-004507.65 (YSG)

Variability From Correlation

• Certain =

– At least two band pairs (N > 5) and (R2 > 0.60)

• Likely =

– At least one band pair (N > 5) and (R2 > 0.60)

R2 V B R B 0.23 (11) R 0.03 (8) 0.39 (4) I 0.00 (6)

• .-- (2)
• .– (2)

M31-004033.80 (OBsg)

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 = $ ∑ 𝑤! 𝜏",!

$

𝑥 𝜀𝑤! = 𝑤! − ̅ 𝑤 𝜏",!

𝐽 = 1 𝑜 𝑜 − 1 &

!"# $

𝜀𝑐!𝜀𝑤! 𝑆 = + ∑ 𝜀𝑐! ∑ 𝜀𝑤!

𝑥 = ' 1 𝜏!,#

$

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%

* Sample adjusted for bias

(Martin & Humphreys, 2017, AJ, 154, 81)

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 (mv < 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/ mv < 18.5 Variable? mv < 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)

R2 V B R B 0.83 (16) R 0.70 (11) 0.71 (8) I 0.39 (13) 0.56 (3)

• .– (1)

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.

Exceptional Example

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

Red Supergiants

• Candidates identified in M31

– Down to Mv~ -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