IC 348 proper motion study from digitised Schmidt plates

Astronomy and Astrophysics Supplement Series, Jul 2018

A new proper motion study for about 1400 stars with  mag in a one square degree region around the young open cluster IC 348 based on Schmidt plates is presented. With an overall accuracy of about 3 mas/yr (2.5 mas/yr, respectively for all stars with  mag) we have obtained membership probabilities dividing our sample into three groups: foreground stars, cluster stars and background stars. This separation is also supported by the proper motion distribution with respect to the direction of the standard antapex and an increase of mean proper motion cluster membership probabilities with smaller cluster radii. 240 stars of our sample have cluster membership probabilities larger than 80%. The results are compared with the highly accurate proper motion study of Fredrick (1956) and with other catalogues (PPM, ACT, Hipparcos), all containing only bright stars. From PPM and ACT proper motions a cluster radius of about 30 arcmin can be assumed. Hipparcos proper motions and parallaxes allow the separation of foreground stars, cluster stars and background stars in a somewhat larger region around IC 348 (with distances from the cluster centre of up to 85 arcmin). On the basis of Hipparcos data we calculate a mean distance of  pc for the cluster stars with common proper motion. This is nearly the same distance as obtained by de Zeeuw et al. (1999) for the Per OB 2 association covering more than square degrees. The mean proper motion of the cluster IC 348 obtained in our study is in good agreement with that of the highly probable members of the Per OB 2 association according to de Zeeuw et al. (1999). Therefore, we conclude that the cluster IC 348 is embedded in the Per OB 2 association. From our proper motion membership probabilities we found a cluster radius of 10-15 arcmin. There is a concentration of Fredrick's highly probable cluster stars just in between our cluster stars and the distant field stars proper motion distributions. On the other hand, two groups of stars in the proper motion diagram of Fredrick (1956) also seem to be indicated if all his possible cluster members are considered. The X-ray sources from Preibisch et al. (1996) identified with optical counterparts from our proper motion sample show a strong concentration in the proper motion diagram. For these objects which are likely T Tauri stars we obtained high membership probabilities so that we conclude that they belong to the cluster IC 348 and to the Per OB 2 association. The proper motion foreground stars and cluster members which are counterparts of near-infrared (NIR) sources (Lada & Lada 1995) are located in different parts of the two colour diagram, respectively.

A PDF file should load here. If you do not see its contents the file may be temporarily unavailable at the journal website or you do not have a PDF plug-in installed and enabled in your browser.

Alternatively, you can download the file locally and open with any standalone PDF reader:

https://aas.aanda.org/articles/aas/pdf/1999/11/ds8401.pdf

IC 348 proper motion study from digitised Schmidt plates

Astron. Astrophys. Suppl. Ser. IC 348 proper motion study from digitised Schmidt plates R.-D. Scholz 2 J. Brunzendorf 1 G. Ivanov / 0 N. Kharchenko 0 B. Lasker 5 H. Meusinger 1 T. Preibisch 3 4 E. Schilbach 2 H. Zinnecker 2 0 Main Astronomical Observatory , Golosiiv, 252127 Kiev , Ukraine 1 Thu ̈ringer Landessternwarte Tautenburg , D 2 Astrophysikalisches Institut Potsdam , An der Sternwarte 16, D 3 Max-Planck-Institut fu ̈r Radioastronomie , Auf dem Hu ̈gel 69, D 4 Astronomisches Institut Universit ̈at Wu ̈rzburg , Am Hubland, D 5 Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218 , U.S.A 6 53121 Bonn , Germany A new proper motion study for about 1400 stars with R < 18 mag in a one square degree region around the young open cluster IC 348 based on Schmidt plates is presented. With an overall accuracy of about 3 mas/yr (2.5 mas/yr, respectively for all stars with R < 17 mag) we have obtained membership probabilities dividing our sample into three groups: foreground stars, cluster stars and background stars. This separation is also supported by the proper motion distribution with respect to the direction of the standard antapex and an increase of mean proper motion cluster membership probabilities with smaller cluster radii. 240 stars of our sample have cluster membership probabilities larger than 80%. The results are compared with the highly accurate proper motion study of Fredrick (1956) and with other catalogues (PPM, ACT, Hipparcos), all containing only bright stars. From PPM and ACT proper motions a cluster radius of about 30 arcmin can be assumed. Hipparcos proper motions and parallaxes allow the separation of foreground stars, cluster stars and background stars in a somewhat larger region around IC 348 (with distances from the cluster centre of up to 85 arcmin). On the basis of Hipparcos data we calculate a mean distance of 261+−2273 pc for the cluster stars with common proper motion. This is nearly the same distance as obtained by de Zeeuw et al. (1999) for the Per OB 2 association covering more than 15 10 square degrees. The mean proper motion of the cluster IC 348 obtained in our study is in good agreement with that of the highly probable members of the Per OB 2 association according to de Zeeuw et al. (1999). Therefore, we astrometry | methods; statistical | open clusters and associations; individual; IC 348 | stars; kinematics - conclude that the cluster IC 348 is embedded in the Per OB 2 association. From our proper motion membership probabilities we found a cluster radius of 10 − 15 arcmin. There is a concentration of Fredrick's highly probable cluster stars just in between our cluster stars and the distant eld stars proper motion distributions. On the other hand, two groups of stars in the proper motion diagram of Fredrick (1956) also seem to be indicated if all his possible cluster members are considered. The X-ray sources from Preibisch et al. (1996) identi ed with optical counterparts from our proper motion sample show a strong concentration in the proper motion diagram. For these objects which are likely T Tauri stars we obtained high membership probabilities so that we conclude that they belong to the cluster IC 348 and to the Per OB 2 association. The proper motion foreground stars and cluster members which are counterparts of nearinfrared (NIR) sources (Lada & Lada 1995) are located in di erent parts of the (J − H) − (H − K) two colour diagram, respectively. 1. Introduction IC 348 is a very young cluster located near the edge of the Perseus molecular cloud complex at a distance of about 300 pc (cf. Herbig 1998) . Since the most massive star of the mass function or the star formation history, could be the cluster (BD 31 643) is only a B5V star, which is not determined more reliably. powerful enough to disperse the cloud in which the stars A proper motion study might help to nd the weak-line were born, the cluster is still embedded in the remnant T Tauri stars in the outer regions of IC 348. It might also molecular core and most stars are obscured by 2 or more provide evidence for the presumption that IC 348 is part mag of visual extinction. The cluster was long believed to of the Per OB 2 association (cf. de Zeeuw et al. 1999) . consist of just a dozen T Tauri members ( Herbig 1954 ; Unfortunately, not much was known about the kinemat Harris et al. 1954 ). However, recent sensitive observations ics of the stars in this region before our study. The only have shown that it is much richer. proper motion study of IC 348 performed so far is that Preibisch et al. (1996) performed very deep ROSAT of Frederick (1956), who classi ed 17 stars as probable observations of IC 348 and could detect more than 100 cluster members. His membership investigation was based X-ray sources in a 1 radius eld. Many of these X-ray not only on highly accurate proper motions but also on sources could be identi ed with H emitting T Tauri stars. the V − (B − V ) col (...truncated)


This is a preview of a remote PDF: https://aas.aanda.org/articles/aas/pdf/1999/11/ds8401.pdf

R.-D. Scholz, J. Brunzendorf, G. Ivanov, N. Kharchenko, B. Lasker, H. Meusinger, T. Preibisch, E. Schilbach, H. Zinnecker. IC 348 proper motion study from digitised Schmidt plates, Astronomy and Astrophysics Supplement Series, pp. 305-321, Volume 137, Issue 2, DOI: 10.1051/aas:1999249