Abstract

Binary post-AGBs

In recent years, it became clear that among post-AGB candidate stars,binarity is a widespread phenomenon. These binary post-AGB stars havedistinct characteristics which include a broad IR excess, oftenstarting at H or K, pointing to the presence of both hot and cool dustin a disc geometry around the central object, which is typically ofspectral type F or G. There is also growing observational evidencethat the dusty discs are remarkable stable: mixed chemistry is oftenobserved, showing that the formation of the O-rich disc antedated themore recent C-rich transition of the central object. Kinematicalinformation of several objects by CO detections, confirms the presenceof a Keplerian circumbinary disc. Also the dust grain evolution inthose discs is rather different than in outflows with typically ahigher crystallisation fraction. Several objects show evidence forlarge grains and even macroscopic structures weredetected. Coagulation seems to be very efficient: the dustprocessingseems to be very similar as in the protoplanetary discs around youngstellar objects.Although the observational evidence for the presence of a circumbinarydisc is well established, its actual structure but also its formation,stability and evolution remain largely unknown. Moreover, the disc mayhave important dynamical interaction with the binary itself: it maypump up the orbital excentricity which would explain the remarkablehigh eccentricities observed.

Table 1: MIDI Science Demonstration Data

Files Description for HD 52961, SX Cen (post-AGB), and associated calibrators: HD 67852, HD 49161, HD 107446, HD 120404

       File Name                   Target  Science/Calibrator   Category

MIDI.2004-02-10T02:12:24.750.fits  HD52961  SACQUISTION

MIDI.2004-02-10T02:15:16.000.fits  HD52961  SFRINGE_SEARCH

MIDI.2004-02-10T02:16:16.266.fits  HD52961  SFRINGE_SEARCH

MIDI.2004-02-10T02:17:16.532.fits  HD52961  SFRINGE_SEARCH

MIDI.2004-02-10T02:20:02.000.fits  HD52961  SFRINGE_TRACK

MIDI.2004-02-10T02:21:02.266.fits  HD52961  SFRINGE_TRACK

MIDI.2004-02-10T02:22:02.532.fits  HD52961  SFRINGE_TRACK 

MIDI.2004-02-10T02:23:02.798.fits  HD52961  S  FRINGE_TRACK 

MIDI.2004-02-10T02:24:03.065.fits  HD52961  S FRINGE_TRACK

MIDI.2004-02-10T02:25:03.330.fits  HD52961  SFRINGE_TRACK

MIDI.2004-02-10T02:29:23.750.fits  HD52961  SPHOTO_A

MIDI.2004-02-10T02:30:45.750.fits  HD52961  SPHOTO_B

MIDI.2004-02-10T02:39:14.250.fits  HD49161  CACQUISITION

MIDI.2004-02-10T02:42:16.000.fits  HD49161  CFRINGE_SEARCH

MIDI.2004-02-10T02:43:09.149.fits  HD49161  CFRINGE_SEARCH

MIDI.2004-02-10T02:45:52.000.fits  HD49161  CFRINGE_TRACK

MIDI.2004-02-10T02:46:52.266.fits  HD49161  CFRINGE_TRACK

MIDI.2004-02-10T02:47:52.532.fits  HD49161  CFRINGE_TRACK

MIDI.2004-02-10T02:48:52.798.fits  HD49161  CFRINGE_TRACK

MIDI.2004-02-10T02:49:53.064.fits  HD49161  CFRINGE_TRACK

MIDI.2004-02-10T02:50:53.331.fits  HD49161  CFRINGE_TRACK

MIDI.2004-02-10T02:54:13.250.fits  HD49161  CPHOTO_A

MIDI.2004-02-10T02:55:39.250.fits  HD49161  CPHOTO_B        

MIDI.2004-02-10T07:30:08.750.fits  SXCEN    SACQUISITION

MIDI.2004-02-10T07:32:27.000.fits  SXCEN    SFRINGE_SEARCH

MIDI.2004-02-10T07:33:27.181.fits  SXCEN    SFRINGE_SEARCH

MIDI.2004-02-10T07:34:27.363.fits  SXCEN    SFRINGE_SEARCH

MIDI.2004-02-10T07:35:27.544.fits  SXCEN    SFRINGE_SEARCH

MIDI.2004-02-10T07:37:52.000.fits  SXCEN    SFRINGE_TRACK

MIDI.2004-02-10T07:38:52.182.fits  SXCEN    SFRINGE_TRACK

MIDI.2004-02-10T07:39:52.363.fits  SXCEN    SFRINGE_TRACK

MIDI.2004-02-10T07:40:52.545.fits  SXCEN    SFRINGE_TRACK

MIDI.2004-02-10T07:49:57.750.fits  SXCEN    SPHOTO_A

MIDI.2004-02-10T07:51:23.750.fits  SXCEN    SPHOTO_B

MIDI.2004-02-10T07:08:04.250.fits  HD67582  CACQUISITION

MIDI.2004-02-10T07:10:21.000.fits  HD67582  CFRINGE_SEARCH

MIDI.2004-02-10T07:11:14.074.fits  HD67582  CFRINGE_SEARCH

MIDI.2004-02-10T07:13:39.075.fits  HD67582  CFRINGE_TRACK

MIDI.2004-02-10T07:14:32.074.fits  HD67582  CFRINGE_TRACK

MIDI.2004-02-10T07:15:25.147.fits  HD67582  CFRINGE_TRACK

MIDI.2004-02-10T07:18:52.750.fits  HD67582  CPHOTO_A

MIDI.2004-02-10T07:20:17.750.fits  HD67582  CPHOTO_B

MIDI.2004-02-11T08:32:04.417.fits  HD144432 SACQUISITION 

MIDI.2004-02-11T08:33:14.750.fits  HD144432 S  ACQUISITION 

MIDI.2004-02-11T08:34:08.250.fits  HD144432 S  ACQUISITION 

MIDI.2004-02-11T08:35:24.250.fits  HD144432 SACQUISITION 

MIDI.2004-02-11T08:36:32.250.fits  HD144432 S ACQUISITION 

MIDI.2004-02-11T08:38:48.250.fits  HD144432 SACQUISITION 

MIDI.2004-02-11T08:44:38.750.fits  HD144432 S ACQUISITION 

MIDI.2004-02-11T08:45:36.250.fits  HD144432 SACQUISITION 

MIDI.2004-02-11T08:46:34.250.fits  HD144432 SACQUISITION 

MIDI.2004-02-11T08:49:36.000.fits  HD144432 S   FRINGE_SEARCH

MIDI.2004-02-11T08:52:25.000.fits  HD144432 SFRINGE_TRACK 

MIDI.2004-02-11T08:53:43.865.fits  HD144432 S FRINGE_TRACK

MIDI.2004-02-11T08:55:02.729.fits  HD144432 S FRINGE_TRACK

MIDI.2004-02-11T08:56:21.593.fits  HD144432 S FRINGE_TRACK

MIDI.2004-02-11T08:57:40.457.fits  HD144432 SFRINGE_TRACK

MIDI.2004-02-11T09:01:27.750.fits  HD144432 SPHOTO_A

MIDI.2004-02-11T09:03:26.250.fits  HD144432 SPHOTO_B

MIDI.2004-02-11T09:11:07.750.fits  HD161892 CACQUISITION

MIDI.2004-02-11T09:12:18.250.fits  HD161892 C   ACQUISITION 

MIDI.2004-02-11T09:13:12.750.fits  HD161892 CACQUISITION 

MIDI.2004-02-11T09:16:21.000.fits  HD161892 C FRINGE_SEARCH

MIDI.2004-02-11T09:19:06.000.fits  HD161892 C FRINGE_TRACK

MIDI.2004-02-11T09:20:24.864.fits  HD161892 C FRINGE_TRACK

MIDI.2004-02-11T09:21:43.728.fits  HD161892 CFRINGE_TRACK

MIDI.2004-02-11T09:23:02.593.fits  HD161892 CFRINGE_TRACK

MIDI.2004-02-11T09:24:21.457.fits  HD161892 CFRINGE_TRACK

MIDI.2004-02-11T09:27:59.250.fits  HD161892 CPHOTO_A

MIDI.2004-02-11T09:30:05.750.fits  HD161892 C   PHOTO_B

MIDI.2004-02-11T04:02:03.250.fits  HD52961  SACQUISITION

MIDI.2004-02-11T04:03:11.750.fits  HD52961  SACQUISITION

MIDI.2004-02-11T04:04:17.750.fits  HD52961  SACQUISITION

MIDI.2004-02-11T04:05:58.250.fitS  HD52961  SACQUISITION

MIDI.2004-02-11T04:08:32.000.fits  HD52961  SFRINGE_SEARCH

MIDI.2004-02-11T04:09:32.182.fits  HD52961  SFRINGE_SEARCH

MIDI.2004-02-11T04:10:32.363.fits  HD52961  SFRINGE_SEARCH

MIDI.2004-02-11T04:13:04.000.fits  HD52961  SFRINGE_TRACK

MIDI.2004-02-11T04:14:04.165.fits  HD52961  SFRINGE_TRACK

MIDI.2004-02-11T04:15:04.346.fits  HD52961  SFRINGE_TRACK

MIDI.2004-02-11T04:16:04.528.fits  HD52961  SFRINGE_TRACK

MIDI.2004-02-11T04:19:08.250.fits  HD52961  SPHOTO_A

MIDI.2004-02-11T04:20:27.250.fits  HD52961  SPHOTO_B

MIDI.2004-02-11T03:33:56.250.fits  HD67582  CACQUISITION

MIDI.2004-02-11T03:35:04.250.fits  HD67582  CACQUISITION

MIDI.2004-02-11T03:38:38.250.fits  HD67582  C ACQUISITION

MIDI.2004-02-11T03:39:29.250.fits  HD67582  CACQUISITION

MIDI.2004-02-11T03:43:01.000.fits  HD67582  CFRINGE_SEARCH

MIDI.2004-02-11T03:43:54.074.fits  HD67582  CFRINGE_SEARCH

MIDI.2004-02-11T03:46:12.000.fits  HD67582  CFRINGE_TRACK

MIDI.2004-02-11T03:47:05.074.fits  HD67582  CFRINGE_TRACK

MIDI.2004-02-11T03:47:58.147.fits  HD67582  CFRINGE_TRACK

MIDI.2004-02-11T03:48:51.221.fits  HD67582  CFRINGE_TRACK

MIDI.2004-02-11T03:52:37.750.fits  HD67582  CPHOTO_A

MIDI.2004-02-11T03:53:51.750.fits  HD67582  CPHOTO_B

MIDI.2004-02-11T07:31:01.250.fits  SXCEN    SACQUISITION

MIDI.2004-02-11T07:32:20.750.fits  SXCEN    SACQUISITION

MIDI.2004-02-11T07:33:15.750.fits  SXCEN    SACQUISITION

MIDI.2004-02-11T07:35:35.000.fits  SXCEN    SFRINGE_SEARCH

MIDI.2004-02-11T07:37:59.000.fits  SXCEN    SFRINGE_TRACK

MIDI.2004-02-11T07:38:52.074.fits  SXCEN    SFRINGE_TRACK

MIDI.2004-02-11T07:39:45.147.fits  SXCEN    S FRINGE_TRACK

MIDI.2004-02-11T07:40:38.221.fits  SXCEN    SFRINGE_TRACK

MIDI.2004-02-11T07:45:12.250.fits  SXCEN    SPHOTO_A

MIDI.2004-02-11T07:46:31.750.fits  SXCEN    SPHOTO_B

MIDI.2004-02-11T08:07:07.750.fits  HD107446 CACQUISITION 

MIDI.2004-02-11T08:08:09.750.fits  HD107446 CACQUISITION

MIDI.2004-02-11T08:09:08.250.fits  HD107446 CACQUISITION

MIDI.2004-02-11T08:09:57.250.fits  HD107446 CACQUISITION

MIDI.2004-02-11T08:14:30.000.fits  HD107446 CFRINGE_SEARCH

MIDI.2004-02-11T08:16:44.000.fits  HD107446 CFRINGE_TRACK

MIDI.2004-02-11T08:17:37.073.fits  HD107446 CFRINGE_TRACK

MIDI.2004-02-11T08:18:30.147.fits  HD107446 CFRINGE_TRACK

MIDI.2004-02-11T08:19:23.221.fits  HD107446 CFRINGE_TRACK

MIDI.2004-02-11T08:23:28.750.fits  HD107446 CPHOTO_A

MIDI.2004-02-11T08:24:48.750.fits  HD107446 CPHOTO_B

MIDI.2004-02-12T09:49:17.250.fits  HD144432 SACQUISITION

MIDI.2004-02-12T09:50:18.250.fits  HD144432 SACQUISITION

MIDI.2004-02-12T09:51:28.250.fits  HD144432 SACQUISITION

MIDI.2004-02-12T09:54:28.000.fits  HD144432 SFRINGE_SEARCH

MIDI.2004-02-12T09:56:45.000.fits  HD144432 SFRINGE_TRACK

MIDI.2004-02-12T09:58:03.864.fits  HD144432 S FRINGE_TRACK

MIDI.2004-02-12T09:59:22.695.fits  HD144432 S FRINGE_TRACK

MIDI.2004-02-12T10:00:41.560.fits  HD144432 SFRINGE_TRACK

MIDI.2004-02-12T10:04:02.250.fits  HD144432 SPHOTO_A

MIDI.2004-02-12T10:05:49.250.fits  HD144432 SPHOTO_B

MIDI.2004-02-12T09:18:57.250.fits  HD161892 CACQUISITION

MIDI.2004-02-12T09:20:14.250.fits  HD161892 CACQUISITION

MIDI.2004-02-12T09:22:09.250.fits  HD161892 C ACQUISITION

MIDI.2004-02-12T09:23:10.750.fits  HD161892 CACQUISITION

MIDI.2004-02-12T09:26:21.000.fits  HD161892 CFRINGE_SEARCH

MIDI.2004-02-12T09:26:56.664.fits  HD161892 CFRINGE_SEARCH

MIDI.2004-02-12T09:29:31.000.fits  HD161892 CFRINGE_TRACK

MIDI.2004-02-12T09:30:49.832.fits  HD161892 C FRINGE_TRACK

MIDI.2004-02-12T09:32:08.696.fits  HD161892 C FRINGE_TRACK

MIDI.2004-02-12T09:33:27.560.fits  HD161892 C FRINGE_TRACK

MIDI.2004-02-12T09:34:46.424.fits  HD161892 CFRINGE_TRACK

MIDI.2004-02-12T09:38:26.750.fits  HD161892 CPHOTO_A

MIDI.2004-02-12T09:40:36.750.fits  HD161892 CPHOTO_B

MIDI.2004-02-12T07:55:05.750.fits  SXCEN    SACQUISITION

MIDI.2004-02-12T07:56:30.750.fits  SXCEN    SACQUISITION

MIDI.2004-02-12T07:57:57.750.fits  SXCEN    SACQUISITION

MIDI.2004-02-12T08:00:33.000.fits  SXCEN    SFRINGE_SEARCH

MIDI.2004-02-12T08:01:26.059.fits  SXCEN    SFRINGE_SEARCH

MIDI.2004-02-12T08:03:25.000.fits  SXCEN    SFRINGE_TRACK

MIDI.2004-02-12T08:04:18.074.fits  SXCEN    SFRINGE_TRACK

MIDI.2004-02-12T08:05:11.148.fits  SXCEN    S FRINGE_TRACK

MIDI.2004-02-12T08:06:04.222.fits  SXCEN    SFRINGE_TRACK

MIDI.2004-02-12T08:09:57.250.fits  SXCEN    SPHOTO_A 

MIDI.2004-02-12T08:11:19.750.fits  SXCEN    SPHOTO_B

MIDI.2004-02-12T07:27:06.750.fits  HD120404 CACQUISITION

MIDI.2004-02-12T07:28:16.750.fits  HD120404 CACQUISITION

MIDI.2004-02-12T07:29:15.750.fits  HD120404 C ACQUISITION

MIDI.2004-02-12T07:30:16.250.fits  HD120404 CACQUISITION

MIDI.2004-02-12T07:33:12.000.fits  HD120404 CFRINGE_SEARCH

MIDI.2004-02-12T07:34:05.149.fits  HD120404 CFRINGE_SEARCH

MIDI.2004-02-12T07:36:34.000.fits  HD120404 CFRINGE_TRACK 

MIDI.2004-02-12T07:37:27.149.fits  HD120404 C  FRINGE_TRACK

MIDI.2004-02-12T07:38:20.295.fits  HD120404 C FRINGE_TRACK

MIDI.2004-02-12T07:39:13.446.fits  HD120404 CFRINGE_TRACK

MIDI.2004-02-12T07:43:27.250.fits  HD120404 CPHOTO_A 

MIDI.2004-02-12T07:44:44.250.fits  HD120404 CPHOTO_B