A study of λ Bootis type stars in the wavelength region beyond 7000 Å

Author(s)

Ernst Paunzen, Inga Kamp, Werner Wolfgang Weiss, Helmut Wiesemeyer

Abstract

The group of ? Bootis type stars comprises late B- to early F-type, Population I objects which are basically metal weak, in particular the Fe group elements, but with the clear exception of C, N, O and S. One of the theories to explain the abundance pattern of these stars involves circumstellar or interstellar matter around the objects. Hence, we have compiled all available data from the literature of well established members of the ? Bootis group redward of 7000 A° in order to find evidence for matter around these objects. Furthermore, we present unpublished ISO as well as submillimeter continuum and CO (2-1) line measurements to complete the data set. In total, measurements for 34 (26 with data redward of 20 œm) well established ? Bootis stars are available. There is evidence for an infrared excesses in six stars (HD 31295, HD 74873, HD 110411, HD 125162, HD 198160/1 and HD 210111) and two are doubtful cases (HD 11413 and HD 192640) resulting in a percentage of 23% (excluding the two doubtful cases). Dust models for these objects show fractional dust luminosities comparable to the Vega-type stars and slightly higher dust temperatures. ISO-SWS spectroscopy for HD 125162 and HD 192640 resulted in the detection of pure stellar HI lines ruling out an active accretion disk (as found for several Herbig Ae/Be stars) around these objects. The submillimeter measurements gave only upper limits for the line and continuum fluxes.

Organisation(s)

Department of Astrophysics

External organisation(s)

Leiden University, Institut de RadioAstronomie Millimétrique (IRAM)

Journal

Astronomy & Astrophysics

Volume

404

Pages

579-591

No. of pages

13

ISSN

0004-6361

Publication date

2003

Peer reviewed

Yes

Austrian Fields of Science 2012

103003 Astronomy

Portal url

https://ucrisportal.univie.ac.at/en/publications/50d80db9-cd80-4f11-af94-9fe98e56b210