TACOS: TESS AM CVn Outbursts Survey

Manuel Pichardo Marcano

Texas Tech University

Liliana Rivera Sandoval, Thomas J. Maccarone, Simone Scaringi

Transiting Exoplanet Survey Satellite (TESS)

AM Canum Venaticorum AM CVn

• White dwarf + White dwarf

• White dwarf + He Star

• Orbital Period: 5-70 minutes

Caltech

Caltech

• Porb 20 to ~ 60 minutes (?)

• Superoutburts (SO) and "Normal" outbursts (NO)

  • SO: Superhumps (periodic brightness variation )

• Disk instability model (DIM)

  •  Constant Mass transfer rate

  • Tidal-thermal disk instability model

Outbursting Systems

Outbursts

Pichardo Marcano et al. (2021)

• Precursor
  • TESS (Duffy et al. 2021)
• Echo Outbursts
• DIM with Enhanced mass transfer (e.g. Hameury & Lasota 2021)

TESS AM CVn Outbursts Survey

Pichardo Marcano et al. (2021)

PTF1 J0719+4858:

• Similar to Dwarf Novae:
  • Hameury et al. (2020)
  • Rivera Sandoval et al. (2021)

Color Evolution

Pichardo Marcano et al. (2021)

Long-term monitoring

Pichardo Marcano et al. (2021)

• Orbital Periods:
  • 2-minute cadence
• Limits on Recurrence Time
• "Normal Outburts"

SO durations vs Porb

Pichardo Marcano et al. (2021)

Summary

• Precursors and "Normal" Outbursts:
  • Relatively Common
  • Short Duration (missed ground-based)
• Echo Outbursts:
  • Different morphology
  • Enhanced Mass Transfer
• SO durations overestimated
• Two new candidate periods
• Color Evolution

Extra Slides

Empirical Relationships

1. Trec prop Porb^7.35
2. Tdur prop Porb^4.54
3. Delta mag prop Porb
4. Long-term
5. Ground-Based:
   1. PTF
   2. CRTS

Levitan et al. 2015

See also Duffy et al. 2021