The search for symbiotic stars in IPHAS

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The search for symbiotic stars in IPHAS

• Romano L.M. Corradi 1,2
• Ernesto Rodriguez-Flores,
• Antonio Mampaso, Kerttu Viironen 2
• Robert Greimel 1
• 1 Isaac Newton Group of Telescopes, La Palma
• 2 Instituto de Astrofisica de Canarias, Tenerife

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Why symbiotic?
Called symbiotic because of their composite
spectrum (Cannon 1910)
Allen 1984 Proc. ASA 5 (3), 421
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Properties of symbiotic stars

• are the interacting binary stars with the
  longest orbital periods

• composed of a hot compact star, usually a white
  dwarf (WD) and a red giant (RG, usually of M-type)

• the binary system is detached ? no Roche lobe
  overflow (some recent controversy about this)

• the WD accretes matter from the RG wind (d M /d
  t 10-8 Msun yr-1)

• RG wind is partially ionized by the WD radiation
  ? strong Ha emission

• mass accretion is near the limit for
  steady-state hydrogen burning on the WD surface
  (? L 1000 Lsun) , but not exactly ? (recurrent)
  thermonuclear runaways (slow novae) ? ejecta
  (fast winds, jets, nebulae)

• S-type (80) RGB star, Porb 200-1000 days
• D-type (20) AGB star, Porb 20-500 (?) yrs,
  extended nebulae

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Significance of the study of symbiotic stars to
Astronomy

• occurrence of thermonuclear outbursts under a
  wide range of conditions
• accretion on WDs and possible progenitors of
  type Ia SNe
• the effects of binarity on the pulsation
  properties of highly evolved stars (Miras)
• formation and destruction of dust and molecules
  in hostile environments
• late stages of stellar evolution in binary
  systems ? formation of aspherical outflows (e.g.
  link with bipolar planetary nebulae)

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Total population of symbiotic stars
BASICALLY UNKNOWN

• Estimated
• 3?103 Allen 1984
• 3?105 Munari y Renzini 1992
• 3?104 Kenyon et al. 1993
• 4?105 Magrini et al. 2003
• Known
• 173

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The search for symbiotics within IPHAS
takes advantage of the strong Ha emission, and
the presence of a bright cool star
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The IPHAS c-c diagram for symbiotics
Rodriguez-Flores 2006, Master Thesis, IAC
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Selection criteria for symbiotics
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The 2MASS c-c diagram for symbiotics
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Selection criteria for symbiotics
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First selection

• IPHAS photometric catalogue from observations
  till Jan 2006 with rlt20 100 million
  stellar-like objects
• With r-Ha above the main-sequence locus (S-type
  selection box) 4 million
• Matched (lt1 arcsec) by objects in 2MASS
  catalogue 700 000
• Observed AND identified twice (lt1 arcsec) in
  IPHAS 178 544

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First selection
178 544 sources
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First selection
D-types, rlt16 59
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First selection
D-types, rlt18 374
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First selection
D-types, rlt20 1197
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First selection
S-types, rlt16 3366
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First selection
S-types, rlt18 18108
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First selection
S-types, rlt20 67363
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Adding a distance parameter
A weighted distance from the centres of the IPHAS
and 2MASS selection boxes defined by a suitable
metrics D w1 d2xIPHAS w2 d2yIPHAS w3
d2x2MASS w4 d2y2MASS (x and y not
orthogonal, follow the inclination of the sides
of the boxes wi are weights, which can be
further split into wi and wi- ) to be used as
a further criterion to select the best candidates
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Adding a distance parameter
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The first new symbiotics of IPHAS
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The first new symbiotics of IPHAS
IPHAS J202510.6435233 r 16.4 2.5mINTIDS 2006
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The first new symbiotics of IPHAS
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The first new symbiotics of IPHAS
IPHAS J185704.5002631 r 18.3 2.5mINTIDS 2006
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The first new symbiotics of IPHAS
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The first new symbiotics of IPHAS
IPHAS J183501.8014656 r 16.4 2.5mINTIDS last
Friday
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Summary

• IPHAS provides a powerful tool to detect new
  symbiotic stars in the Galaxy
• Best effectiveness when combined with 2MASS
• Thousands of candidates selected
• - Better control of bad measurements (e.g.
  clouds)
• - Selection criteria should be refined (avoid
  star forming regions, add IRAS colours?)
• Follow-up spectroscopy started, first 3 new
  symbiotics discovered, investigation of possible
  external collaborations (e.g. Asiago) to
  continue the spectroscopy

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The IPHAS c-c diagram for symbiotics
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The IPHAS c-c diagram for symbiotics
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Hasta fines del 2004, en IPHAS sólo se observaron
5 (/?20) simbióticas Draco C1, ALS 2, AS 245,
MaC 1-9 y DQ Ser. Observaciones
complementarias Fecha 20 de abril, 17 y 18 de
septiembre/2005. Telescopio INT WFC (r, H?,
i) Objetos observados DB 21º 3873, Hen 2-374,
Hen 3-1341, YY Her, LT Del (2), V 1329 Cyg (2),
Hen 2-468, LL Cas, QW Sge, v 1016 Cyg, Z And, HM
Sge y V 471 Per. Varias observaciones de 5
estrellas simbióticas (AG Dra, AG Peg, AX Per, RX
Pup y Z And). Fotometría sintética a partir de
espectros (Mikolajewska 2005).

• Objetos de referencia (grupo 1)
• 67 nebulosas planetarias (NP)
• 121 estrellas variables tipo Mira (VMira)
• 43 estrellas B con líneas de emisión (Be)
• 83 estrellas variables cataclísmicas (VC)

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Two Micron All-Sky Survey (2MASS) junio 1997
febrero 2001
Telescopios 2 reflectores de 1.3 metros de
diámetro c/u (uno en c/hemisferio Mte. Hopkins
(Arizona) y CTIO (Chile )) Filtros J (1.25
?m), H (1.65 ?m) y Ks (2.17 ?m) Límites J lt
15.8, H lt 15.1 y Ks lt 14.3
Objetos de referencia (grupo 2)

• 285 nebulosas planetarias (NP)
• 121 estrellas variables tipo Mira (VMira)
• 76 estrellas B con líneas de emisión (Be)
• 95 estrellas variables cataclísmicas (VC)

...además de 187 de las 188 estrellas simbióticas
conocidas.