HO Puppis: Not a Be Star but a Newly Confirmed IW And-Type Star

Abstract

HO Puppis (HO Pup) was considered as a Be-star candidate based on its gamma-Cassiopeiae-type light curve, but lacked spectroscopic confirmation. Using distance measured from Gaia Data Release 2 and the spectral-energy-distribution (SED) fit on broadband photometry, the Be-star nature of HO Pup is ruled out. Furthermore, based on the 28,700 photometric data points collected from various time-domain surveys and dedicated intensive-monitoring observations, the light curves of HO Pup closely resemble IW And-type stars (as pointed out in Kimura et al. 2020a), exhibiting characteristics such as quasi-standstill phase, brightening, and dips. The light curve of HO Pup displays various variability timescales, including brightening cycles ranging from 23 to 61 days, variations with periods between 3.9 days and 50 minutes during the quasi-standstill phase, and a semi-regular ~14-day period for the dip events. We have also collected time-series spectra (with various spectral resolutions), in which Balmer emission lines and other expected spectral lines for an IW And-type star were detected (even though some of these lines were also expected to be present for Be stars). We detect Bowen fluorescence near the brightening phase, and that can be used to discriminate between IW And-type stars and Be stars. Finally, despite only observing for four nights, the polarization variation was detected, indicating that HO Pup has significant intrinsic polarization.

24 pages, 7 tables and 12 figures; ApJ accepted

References in corpus (14)

• The Zwicky Transient Facility: System Overview, Performance, and First Results
• The Zwicky Transient Facility: Data Processing, Products, and Archive
• The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0
• The Zwicky Transient Facility: Science Objectives
• The Second-Generation Guide Star Catalog: Description and Properties
• The Automated Palomar 60-Inch Telescope
• Magnetic fields and accretion flows on the classical T Tauri star V2129 Oph
• A Fully Automated Integral Field Spectrograph Pipeline for the SEDMachine: pysedm
• Anomalous Z Cam stars: a response to mass-transfer outbursts
• A molecular line survey toward the nearby galaxies NGC 1068, NGC 253, and IC 342 at 3 mm with the Nobeyama 45 m radio telescope: The data
• KIC 9406652: A laboratory of the tilted disk in cataclysmic variable stars
• EX Draconis: Using Eclipses to Separate Outside-In and Inside-Out Outbursts
• Searching for Be Stars in the Open Cluster NGC 663
• The {\it K2} Light Curves and Stunted Outbursts of AC Cnc

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