Proposal #307

Dear members of the AAVSOnet Telescope Allocation Committee,

I submit here a proposal for observational time with one or several of the AAVSOnet telescopes, at your discretion.

Being affiliated with the AAVSO since January 2021 (Observer Code: SAMA), I have taken the AAVSO CHOICE courses Variable Star Classification and Light Curves (Blake Crosby), Introduction to Spectroscopy (Steven Shore), Developing A Visual Observing Program (Richard Roberts), and Photometry using VPhot (Ken Menzies).

My backyard observatory is at -19.95, -44.25, Southeastern Brazil, where I have an 8-in f/10 Meade SCT (LX80) on a Sky-Watcher HEQ5 Pro Synscan, an Imaging Source DMK 41AU02.AS mono, a QHYCCD 5L-II-C, and a ZWO ASI533MM Pro camera; I also have an SA-100 grating and a Star’EX spectroscope (R=10,000 to 15,000).

My goal is the photometric and spectroscopic observation of selected Classical Be stars visible from the Southern hemisphere. I wrote a small review about this spectral class; it can be found in the VSS Newsletter 2022-3 (July) - The B Star Dilemma: To Be or Not to Be.

For the purpose of defining the objects of the intended long-term study, I surveyed the literature plus several catalogs and databases to develop my observing program. What came out from this preliminary survey of the Be stars were the following points:

1. Be stars provide a strategic window for the study of the astrophysics of rapid spinning and very hot stars;

2. The Be stars visible in the Southern hemisphere represent 65% of the total so far identified, but only 15% of the spectra recorded in the ArasBeAm and BeSS databases originate from Southern objects;

3. There are many Be stars in the Southern hemisphere not yet surveyed by photometry, much less by spectroscopy.

This makes it tempting to monitor Be stars visible in the Southern hemisphere while, at the same time, it is urgent to carefully select the initial targets for a long-term observing program. However, it also makes it difficult to carry on an arbitrary selection of targets, for lack of significant and/or updated data for most of the potential Southern hemisphere Classical Be star objects.

For this purpose, I selected 12 targets ranging from mag. 4 to 9, plus alfa Eridani as a reference. This selection was based on data available in VSX and BeSS, taking into account an urgency score established by the latter database, the Be category (only Classical Be stars were chosen) and the variability type (VSX types Be, GCAS, and LERI).

In conclusion, a preliminary survey is needed. And because it will only be feasible for me to observe Be stars from my backyard observatory as of mid-March 2023, when the weather in my area starts to clear up from the rainy season, I need support from the AAVSOnet at this stage.

Currently, the area of the sky that I can visualize from my present observatory ranges from E to SSW (approximately 110˚), Dec. -90˚ through -20˚. A new observatory shall see its first light by the end of 2023 when I will have 330˚ of sky window around me and declination values from +40˚ to -90˚.

In summary: This application aims to have a sample of Be stars and Be candidates scanned photometrically and spectroscopically by the AAVSOnet, to instruct a subsequent pre-selection of targets to be pursued in long-term studies with my own equipment.

After having surveyed the BeSS, ASAS-SN, and TESS databases, I apply here for the initial data collection of the following targets:

R. A. Dec. B V

alf Eri +01:37:42.8 -57:14:12.3 0.3 0.5

gam Cir +15:23:22.6 -59:19:14.8 4.7 4.43-4.52

V795 Cen +14:14:57.1 -57:05:10.1 4.97 4.97-5.1

HP Cma +06:45:31.2 -30:56:56.3 5.61 5.33-5.81

V339 Pup +06:46:12.1 -37:46:31.2 6.078 6.15-6.27

V846 Ara +16:56:08.8 -50:40:29.2 6.31 6.33

NS Vel +08:31:05.93 -39:03:39.47 7.3 7.3±0.01

V426 Pup +08:11:54.8 -30:12:42.8 7.7 7.76±0.01

V1008 Cen +14:33:36.8 -58:49:14.9 7.7 7.71

V353 Car +11:10:02.3 -60:05:42.5 7.63 7.59-7.78

HD148567 +16:31:02.81 -46:28:45.7 8.13 7.84-8.11

V956 Sco +17:07:05.2 -35:45:32.4 8.34 7.9

I look forward to the acceptance of this proposal.

Yours thankfully,

Ariovaldo “Ari” Siqueira, Ph.D.